"一ơ性单?协议?br />服务端不能主动连接客L(fng)Q只能被动等待ƈ{复客户端请求。客L(fng)q接服务端，?br />Z个HTTP RequestQ服务端处理hQƈ且返回一个HTTP Responsel客L(fng)Q本?br />HTTP Request-Response Cyclel束?br />我们看到QHTTP协议本nq不能支持服务端保存客户端的状态信息。于是，W(xu)eb Server
中引入了(jin)session的概念，用来保存客户端的状态信息?br />q里用一个Ş象的比喻来解释session的工作方式。假设W(wng)eb Server是一个商场的存包
处，HTTP Request是一个顾客，W一ơ来到存包处Q管理员把顾客的物品存放在某一?br />柜子里面Q这个柜子就相当于SessionQ，然后把一个号码牌交给q个֮Q作为取?a name="entrymore">
凭证Q这个号码牌是Session IDQ。顾客（HTTP RequestQ下一ơ来的时候，p?br />L(fng)牌（Session IDQ交l存包处QWeb ServerQ的理员。管理员Ҏ(gu)L(fng)?br />QSession IDQ找到相应的柜子QSessionQ，Ҏ(gu)֮QHTTP RequestQ的hQW(xu)eb
Server可以取出、更换、添加柜子（SessionQ中的物品，W(xu)eb Server也可以让֮
QHTTP RequestQ的L(fng)牌和L(fng)牌对应的柜子QSessionQ失效。顾客（HTTP
RequestQ的忘性很大，理员在֮回去的时候（HTTP ResponseQ都要重新提醒顾?br />C自己的号码牌QSession IDQ。这P֮QHTTP RequestQ下ơ来的时候，又
带着L(fng)牌回来了(jin)?br />Session ID实际上是在客L(fng)和服务端之间通过HTTP Request和HTTP Response传来?br />ȝ。号码牌QSession IDQ必d含在HTTP Request里面。关于HTTP Request的具?br />格式Q请参见HTTP协议Q?<http://www.w3.org/Protocols/>
http://www.w3.org/Protocols/Q。这里只做一个简单的介绍?br />在Java Web ServerQ即Servlet/JSP ServerQ中QSession ID用jsessionid表示Q请
参见Servlet规范Q?br />HTTP Request一般由3部分l成Q?br />Q?QRequest Line
q一行由HTTP MethodQ如GET或POSTQ、URL、和HTTP版本L(fng)成?br />例如QGET http://www.w3.org/pub/WWW/TheProject.html HTTP/1.1
GET http://www.google.com/search?q=Tomcat HTTP/1.1
POST http://www.google.com/search HTTP/1.1
GET http://www.somsite.com/menu.do;jsessionid=1001 HTTP/1.1
Q?QRequest Headers
q部分定义了(jin)一些重要的头部信息Q如Q浏览器的种c，语言Q类型。Request
Headers中还可以包括Cookie的定义。例如：(x)
User-Agent: Mozilla/4.0 (compatible; MSIE 5.5; Windows NT 5.0)
Accept-Language: en-us
Cookie: jsessionid=1001
Q?QMessage Body
如果HTTP Method是GETQ那么Message Body为空?br />如果HTTP Method是POSTQ说明这个HTTP Request是submit一个HTML Form的结果，
那么Message Body为HTML Form里面定义的Input属性。例如，
user=guest
password=guest
jsessionid=1001
LQ如果把HTML Form元素的Method属性改为GET。那么，Message Body为空Q所有的
Input属性都?x)加在URL的后面。你在浏览器的URL地址栏中?x)看到这些属性，cM?br />http://www.somesite/login.do?user=guest&password=guest&jsessionid=1001
从理Z来说Q这3个部分（Request URLQCookie Header, Message BodyQ都可以?br />来存放Session ID。由于Message BodyҎ(gu)必须需要一个包含Session ID的HTML
FormQ所以这U方法不通用?br />一般用来实现Session的方法有两种Q?br />Q?QURL重写?br />Web Server在返回Response的时候，(g)查页面中所有的URLQ包括所有的q接Q和HTML
Form的Action属性，在这些URL后面加上";jsessionid=XXX"?br />下一ơ，用户讉Kq个面中的URL。jsessionid׃(x)传回到Web Server?br />Q?QCookie?br />如果客户端支持CookieQW(xu)eb Server在返回Response的时候，在Response的Header?br />分，加入一?set-cookie: jsessionid=XXXX"header属性，把jsessionid攑֜
Cookie里传到客L(fng)?br />客户端会(x)把Cookie存放在本地文仉Q下一ơ访问Web Server的时候，再把Cookie的信
息放到HTTP Request?Cookie"header属性里面，q样jsessionid随着HTTP
Requestq回lWeb Server?br />
二、相兌?br />
前面是我自作聪明的一D个人浅见，下面我来扄权威资料支持?br /><http://www.w3.org/Protocols/> http://www.w3.org/Protocols/
Use of HTTP State Management (
<ftp://ftp.rfc-editor.org/in-notes/rfc2964.txt> RFC 2964).
<ftp://ftp.rfc-editor.org/in-notes/rfc2964.txt>
ftp://ftp.rfc-editor.org/in-notes/rfc2964.txt
q个文g是定?HTTP State Management"扩展协议部分。里面有q么一D，
It's important to realize that similar capabilities may also be (tng) (tng) (tng) (tng)achieved
using the "bare" HTTP protocol, and/or dynamically-generated
HTML, without the State Management extensions. (tng) (tng)For example, state
information can be transmitted from the service to the user by (tng) (tng) (tng) (tng)embedding
a session identifier in one or more URLs which appear in HTTP redirects, or
dynamically generated HTML; and the state information may be returned from
the user to the service when such URLs appear in a GET or POST request.
HTML forms can also be used to pass state information from the service to
the user and back, without the user being aware of this happening.
q段话的意思是_(d)不用q个 "HTTP State Management"扩展协议部分Q我们也可以
?Ua(b)"的HTTP协议实现Session -- 比如URL重写QHTML Form{?br />q里面没有提到Cookie。因?HTTP State Management" 扩展协议部分本n包括?jin)?br />于Cookie的内宏V这一点可以通过
HTTP State Management Mechanism (RFC 2965
<ftp://ftp.rfc-editor.org/in-notes/rfc2965.txt> ),
<ftp://ftp.rfc-editor.org/in-notes/rfc2965.txt>
ftp://ftp.rfc-editor.org/in-notes/rfc2965.txt
看出来?br />
STATE AND SESSIONS
This document describes a way to create stateful sessions with HTTP
requests and responses. (tng) (tng)Currently, HTTP servers respond to each (tng) (tng) (tng) (tng)client
request without relating that request to previous or (tng) (tng) (tng) (tng)subsequent requests;
the state management mechanism allows clients (tng) (tng) (tng) (tng)and servers that wish to
exchange state information to place HTTP (tng) (tng) (tng) (tng)requests and responses within a
larger context, which we term a (tng) (tng) (tng) (tng)"session". (tng) (tng)This context might be used to
create, for example, a (tng) (tng) (tng) (tng)"shopping cart", in which user selections can be
aggregated before (tng) (tng) (tng) (tng)purchase, or a magazine browsing system, in which a
user's previous (tng) (tng) (tng) (tng)reading affects which offerings are presented.
Neither clients nor servers are required to support cookies. (tng) (tng)A (tng) (tng) (tng) (tng)server
MAY refuse to provide content to a client that does not return (tng) (tng) (tng) (tng)the
cookies it sends.
后面q给Z(jin)例子Q其中的汉语部分是我加的Q?br />
4.1 (tng) (tng)Example 1
Most detail of request and response headers has been omitted. (tng) (tng)Assume
the user agent has no stored cookies.
(tng) (tng) (tng) (tng) 1. User Agent -> Server
(tng) (tng) (tng) (tng) (tng) (tng) POST /acme/login HTTP/1.1
(tng) (tng) (tng) (tng) (tng) (tng) [form data]
(tng) (tng) (tng) (tng) (tng) (tng) User identifies self via a form.
(tng) (tng) (tng) (tng) 2. Server -> User Agent
(tng) (tng) (tng) (tng) (tng) (tng) HTTP/1.1 200 OK
(tng) (tng) (tng) (tng) (tng) (tng) Set-Cookie2: Customer="WILE_E_COYOTE"; Version="1"; Path="/acme"
(tng) (tng) (tng) (tng) (tng) (tng) Cookie reflects user's identity.
Q这里面?Customer="WILE_E_COYOTE" 应该是从Form Data里面来的Q这时候又?br />回给?jin)客L(fng)Q?br />
(tng) (tng) (tng) (tng) 3. User Agent -> Server
(tng) (tng) (tng) (tng) (tng) (tng) POST /acme/pickitem HTTP/1.1
(tng) (tng) (tng) (tng) (tng) (tng) Cookie: $Version="1"; Customer="WILE_E_COYOTE"; $Path="/acme"
(tng) (tng) (tng) (tng) (tng) (tng) [form data]
(tng) (tng) (tng) (tng) (tng) (tng) User selects an item for "shopping basket".
(tng) (tng) (tng) (tng) 4. Server -> User Agent
(tng) (tng) (tng) (tng) (tng) (tng) HTTP/1.1 200 OK
(tng) (tng) (tng) (tng) (tng) (tng) Set-Cookie2: Part_Number="Rocket_Launcher_0001"; Version="1";
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) Path="/acme"
(tng) (tng) (tng) (tng) (tng) (tng) Shopping basket contains an item.
Q这个火发器昄也是从Form Data来的。但Z?br />Part_Number="Rocket_Launcher_0001"也需要传回给客户端？
Customer="WILE_E_COYOTE"; 应该是在传统?Set-Cookie"里面传回l客L(fng)的?
Set-Cookie2" 的作用应该是向Cookie里面d东西。）(j)
(tng) (tng) (tng) (tng) 5. User Agent -> Server
(tng) (tng) (tng) (tng) (tng) (tng) POST /acme/shipping HTTP/1.1
(tng) (tng) (tng) (tng) (tng) (tng) Cookie: $Version="1";
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) Customer="WILE_E_COYOTE"; $Path="/acme";
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) Part_Number="Rocket_Launcher_0001"; $Path="/acme"
(tng) (tng) (tng) (tng) (tng) (tng) [form data]
(tng) (tng) (tng) (tng) (tng) (tng) User selects shipping method from form.
Q客户传l服务器的Cookie里面包括?jin)Customer和Part_NumberQ?br />
(tng) (tng) (tng) (tng) 6. Server -> User Agent
(tng) (tng) (tng) (tng) (tng) (tng) HTTP/1.1 200 OK
(tng) (tng) (tng) (tng) (tng) (tng) Set-Cookie2: Shipping="FedEx"; Version="1"; Path="/acme"
(tng) (tng) (tng) (tng) (tng) (tng) New cookie reflects shipping method.
(tng) (tng) (tng) (tng) 7. User Agent -> Server
(tng) (tng) (tng) (tng) (tng) (tng) POST /acme/process HTTP/1.1
(tng) (tng) (tng) (tng) (tng) (tng) Cookie: $Version="1";
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) Customer="WILE_E_COYOTE"; $Path="/acme";
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) Part_Number="Rocket_Launcher_0001"; $Path="/acme";
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) Shipping="FedEx"; $Path="/acme"
(tng) (tng) (tng) (tng) (tng) (tng) [form data]
(tng) (tng) (tng) (tng) (tng) (tng) User chooses to process order.
(tng) (tng) (tng) (tng) 8. Server -> User Agent
(tng) (tng) (tng) (tng) (tng) (tng) HTTP/1.1 200 OK
(tng) (tng) (tng) (tng) (tng) (tng) Transaction is complete.
(tng) (tng)The user agent makes a series of requests on the origin server, after
each of which it receives a new cookie. (tng) (tng)All the cookies have the same Path
attribute and (default) domain. (tng) (tng)Because the request-URIs all path-match
/acme, the Path attribute of each cookie, each request contains all the
cookies received so far.
Q看到这里，我才大致明白Q原来那?Path="/acme" 大致L(fng) JSessionID的作用）(j)
三、Tomcat5的HTTP Session实现
下面我们来看Tomcat5的源代码如何支持HTTP 1.1 Session?br />我们可以用jsessionid, Set-Cookie{关键字搜烦(ch)Tomcat5源代码?br />
首先Q我们来看常量定义：(x)
org.apache.catalina.Globals
(tng) (tng) /**
(tng) (tng) (tng) (tng)* The name of the cookie used to pass the session identifier back
(tng) (tng) (tng) (tng)* and forth with the client.
(tng) (tng) (tng) (tng)*/
(tng) (tng) public static final String SESSION_COOKIE_NAME = "JSESSIONID";
(tng) (tng) /**
(tng) (tng) (tng) (tng)* The name of the path parameter used to pass the session identifier
(tng) (tng) (tng) (tng)* back and forth with the client.
(tng) (tng) (tng) (tng)*/
public static final String SESSION_PARAMETER_NAME = "jsessionid";
Cookie里面用大写的JSESSIONIDQURL后缀用的是小写的jsessionid?br />Session的具体实现类是org.apache.catalina.session.StandardSession。一个Tomcat
Server的所有Session都由一个ManagerQ拥有一个ContextQ统一理。我估计有一?br />Session Listener 专门理Cluster之间的Session数据复制Q具体的我没有追查下
厅R?br />
另外几个重要的相关类是org.apache.coyote.tomcat5包下面的CoyoteRequest ,
CoyoteResponse, CoyoteAdapter三个cR?br />
org.apache.coyote.tomcat5.CoyoteResponsecȝtoEncoded()Ҏ(gu)支持URL重写?br />String toEncoded(String url, String sessionId) {
...
(tng) (tng) (tng) (tng) (tng) (tng) StringBuffer sb = new StringBuffer(path);
(tng) (tng) (tng) (tng) (tng) (tng) if( sb.length() > 0 ) { // jsessionid can't be first.
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) sb.append(";jsessionid=");
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) sb.append(sessionId);
(tng) (tng) (tng) (tng) (tng) (tng) }
(tng) (tng) (tng) (tng) (tng) (tng) sb.append(anchor);
(tng) (tng) (tng) (tng) (tng) (tng) sb.append(query);
(tng) (tng) (tng) (tng) (tng) (tng) return (sb.toString());
}
我们来看org.apache.coyote.tomcat5.CoyoteRequest的两个方?br />configureSessionCookie()
doGetSession()用Cookie支持jsessionid.
(tng) (tng) /**
(tng) (tng) (tng) (tng)* Configures the given JSESSIONID cookie.
(tng) (tng) (tng) (tng)*
(tng) (tng) (tng) (tng)* @param cookie The JSESSIONID cookie to be configured
(tng) (tng) (tng) (tng)*/
(tng) (tng) protected void configureSessionCookie(Cookie cookie) {
(tng) (tng) (tng) (tng) (tng) (tng)...
(tng) (tng) }
(tng) (tng) HttpSession doGetSession(boolean create){
(tng) (tng) (tng) (tng) ...
(tng) (tng) (tng) (tng) (tng) (tng) // Creating a new session cookie based on that session
(tng) (tng) (tng) (tng) (tng) (tng) if ((session != null) && (getContext() != null)
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng)&& getContext().getCookies()) {
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) Cookie cookie = new Cookie(Globals.SESSION_COOKIE_NAME,
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng)session.getId());
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) configureSessionCookie(cookie);
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) ((HttpServletResponse) response).addCookie(cookie);
(tng) (tng) (tng) (tng) (tng) (tng) }
(tng) (tng) (tng) (tng) ...
(tng) (tng) }
四、More
HTTP Session的协议、规范、实现大概就是这些?br />另外Q在frameset中用Session的情冉|些复杂，不同环境表现可能不同?br />其余相关的概忉|"单点d"(Sing Sign On - SSO), Domain, Cluster, Proxy,
Cache{?!-- Added by RelatedTopic, plugin for Bo-Blog 2.0.0 -->
]]>
每个软g中都有权限这个功能，搞了(jin)个通过tag实现的方?复用性很强，
psy-operation.tld
Xml代码
<?xml version="1.0" encoding="UTF-8" ?> (tng)
<taglib xmlns=" (tng) (tng) (tng) xmlns:xsi=" (tng) (tng) (tng) xsi:schemaLocation="http://www.blog.com.cn/http://java.sun.com/xml/ns/j2ee (tng) (tng) (tng) version=" (tng) <description> (tng)
(tng)psychcn 标记?1.0 (tng) (tng)
(tng) </description> (tng)
(tng) <tlib-version>1.0</tlib-version> (tng)
(tng) <short-name>psydict</short-name> (tng)
(tng) <uri>http://www.psychcn.com/taglibs</uri> (tng)
(tng) (tng) (tng) <tag> (tng)
(tng) (tng) (tng) <name>op</name> (tng)
(tng) (tng) (tng) <description>权限标签</description> (tng)
(tng) (tng) (tng) <tag-class>com.psychcn.web.tags.OperationTag</tag-class> (tng)
(tng)<body-content>scriptless</body-content> (tng)
(tng) (tng) (tng) (tng) (tng) (tng)
(tng) (tng) (tng) <attribute> (tng)
(tng) (tng) (tng) (tng) (tng) (tng) <name>code</name> (tng)
(tng) (tng) (tng) (tng) (tng) (tng) <required>true</required> (tng)
(tng) (tng) (tng) (tng) (tng) (tng) <rtexprvalue>true</rtexprvalue> (tng)
(tng) (tng) (tng) </attribute> (tng)
(tng) (tng) (tng) <attribute> (tng)
(tng) (tng) (tng) (tng) (tng) (tng) <name>opset</name> (tng)
(tng) (tng) (tng) (tng) (tng) (tng) <required>false</required> (tng)
(tng) (tng) (tng) (tng) (tng) (tng) <rtexprvalue>true</rtexprvalue> (tng)
(tng) (tng) (tng) </attribute> (tng) (tng) (tng) (tng) (tng) (tng)
(tng) </tag> (tng)
</taglib> (tng)
<?xml version="1.0" encoding="UTF-8" ?>
<taglib xmlns=" (tng) (tng) (tng) xmlns:xsi=" (tng) (tng) (tng) xsi:schemaLocation="http://www.blog.com.cn/http://java.sun.com/xml/ns/j2ee (tng) (tng) (tng) version=" (tng) <description>
(tng)psychcn 标记?1.0
(tng) </description>
(tng) <tlib-version>1.0</tlib-version>
(tng) <short-name>psydict</short-name>
(tng) <uri>http://www.psychcn.com/taglibs</uri>
(tng) (tng) (tng) <tag>
(tng) (tng) (tng) <name>op</name>
(tng) (tng) (tng) <description>权限标签</description>
(tng) (tng) (tng) <tag-class>com.psychcn.web.tags.OperationTag</tag-class>
(tng)<body-content>scriptless</body-content>
(tng) (tng) (tng)
(tng) (tng) (tng) <attribute>
(tng) (tng) (tng) (tng) (tng) (tng) <name>code</name>
(tng) (tng) (tng) (tng) (tng) (tng) <required>true</required>
(tng) (tng) (tng) (tng) (tng) (tng) <rtexprvalue>true</rtexprvalue>
(tng) (tng) (tng) </attribute>
(tng) (tng) (tng) <attribute>
(tng) (tng) (tng) (tng) (tng) (tng) <name>opset</name>
(tng) (tng) (tng) (tng) (tng) (tng) <required>false</required>
(tng) (tng) (tng) (tng) (tng) (tng) <rtexprvalue>true</rtexprvalue>
(tng) (tng) (tng) </attribute> (tng) (tng) (tng)
(tng) </tag>
</taglib>
OperationTag.java
Java代码
import javax.servlet.jsp.JspException; (tng) (tng)
import javax.servlet.jsp.tagext.SimpleTagSupport; (tng) (tng)
(tng)
import java.io.IOException; (tng) (tng)
import java.util.*; (tng) (tng)
(tng)
public class OperationTag extends SimpleTagSupport { (tng) (tng)
(tng)private Set operation_set; (tng) (tng)
(tng)private String default_operation_set_name = "ops"; (tng) (tng)
(tng)private String code; (tng) (tng)
(tng) (tng) (tng)
(tng)public void setCode(String code) { (tng) (tng)
(tng) this.code = code; (tng) (tng)
(tng)} (tng) (tng)
(tng)public void setOpset(Set operation_set) { (tng) (tng)
(tng) this.operation_set = operation_set; (tng) (tng)
(tng)} (tng) (tng)
(tng)public void setOpsetName(String name) { (tng) (tng)
(tng) this.default_operation_set_name= name; (tng) (tng)
(tng)} (tng) (tng)
(tng) (tng) (tng)
(tng)public void doTag() throws JspException, IOException{ (tng) (tng)
(tng) //session中没有设|权限HashSet,l默认值?tng)?
(tng) if (operation_set==null) { (tng) (tng)
(tng) (tng) Object o = this.getJspContext().findAttribute(default_operation_set_name); (tng) (tng)
(tng) (tng) if (o instanceof Set) (tng) (tng)
(tng) (tng) (tng) operation_set = (Set)o; (tng) (tng)
(tng) } (tng) (tng)
(tng) (tng) (tng) (tng)
(tng) if (code == null || operation_set == null) (tng) (tng)
(tng) (tng) throw new JspException("标签属性无?无法执行!"); (tng) (tng)
(tng) (tng) (tng) (tng)
(tng) //q里支持多个code,?,'分割,有一个符合条件就输出,全部不满_不输?注意不能有空?区分大小? (tng) (tng)
(tng) String[] codes = code.split(","); (tng) (tng)
(tng) for (String s : codes) { (tng) (tng)
(tng) (tng) if (operation_set.contains(s)) { (tng) (tng)
(tng) (tng) (tng) this.getJspBody().invoke(this.getJspContext().getOut()); (tng) (tng)
(tng) (tng) (tng) return; (tng) (tng)
(tng) (tng) } (tng) (tng)
(tng) } (tng) (tng)
(tng)} (tng) (tng)
} (tng)
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.SimpleTagSupport;
import java.io.IOException;
import java.util.*;
public class OperationTag extends SimpleTagSupport {
(tng)private Set operation_set;
(tng)private String default_operation_set_name = "ops";
(tng)private String code;
(tng)
(tng)public void setCode(String code) {
(tng) this.code = code;
(tng)}
(tng)public void setOpset(Set operation_set) {
(tng) this.operation_set = operation_set;
(tng)}
(tng)public void setOpsetName(String name) {
(tng) this.default_operation_set_name= name;
(tng)}
(tng)
(tng)public void doTag() throws JspException, IOException{
(tng) //session中没有设|权限HashSet,l默认?br /> (tng) if (operation_set==null) {
(tng) (tng) Object o = this.getJspContext().findAttribute(default_operation_set_name);
(tng) (tng) if (o instanceof Set)
(tng) (tng) (tng) operation_set = (Set)o;
(tng) }
(tng)
(tng) if (code == null || operation_set == null)
(tng) (tng) throw new JspException("标签属性无?无法执行!");
(tng)
(tng) //q里支持多个code,?,'分割,有一个符合条件就输出,全部不满_不输?注意不能有空?区分大小?
(tng) String[] codes = code.split(",");
(tng) for (String s : codes) {
(tng) (tng) if (operation_set.contains(s)) {
(tng) (tng) (tng) this.getJspBody().invoke(this.getJspContext().getOut());
(tng) (tng) (tng) return;
(tng) (tng) }
(tng) }
(tng)}
}
(tng)
(tng)
底层查找权限接口Q?/p>
OperationService.java
Java代码
public java.util.HashSet<String> findByUserId(String userId) throws Exception; (tng) (tng)
实现接口c：(x)(//通过USERID扑ֈ对应的operation的code) (tng) (tng)
(tng)
OperationServiceImpImp.java (tng) (tng)
(tng)
(tng)public java.util.HashSet<String> findByUserId(String userId) throws Exception{ (tng) (tng)
(tng) Session s = getSession(); (tng) (tng)
(tng) Transaction tx = s.beginTransaction(); (tng) (tng)
(tng) (tng) (tng) (tng)
(tng) String sql = "select DISTINCT o.code from users u " + (tng) (tng)
(tng) (tng) (tng) (tng) (tng) "inner join groupmember gm on u.userId=gm.user_Id " + (tng) (tng) (tng)
(tng) (tng) (tng) (tng) (tng) "inner join groupacl ga on gm.group_id=ga.group_id " + (tng) (tng)
(tng) (tng) (tng) (tng) (tng) "inner join operation o on ga.op_id = o.id " + (tng) (tng)
(tng) (tng) (tng) (tng) (tng) "where u.userId=?"; (tng) (tng)
(tng) Query q = s.createSQLQuery(sql).setString(0,userId); (tng) (tng)
(tng) List<Object> ls = q.list(); (tng) (tng)
(tng) HashSet ops = new HashSet(); (tng) (tng)
(tng) for(Object object : ls){ (tng) (tng)
(tng) (tng) ops.add(object); (tng) (tng)
(tng) } (tng) (tng)
(tng) tx.commit(); (tng) (tng)
(tng) releaseSession(s); (tng) (tng)
(tng) (tng) (tng) (tng)
(tng) return ops; (tng) (tng)
(tng)} (tng)
public java.util.HashSet<String> findByUserId(String userId) throws Exception;
实现接口c：(x)(//通过USERID扑ֈ对应的operation的code)
OperationServiceImpImp.java
(tng)public java.util.HashSet<String> findByUserId(String userId) throws Exception{
(tng) Session s = getSession();
(tng) Transaction tx = s.beginTransaction();
(tng)
(tng) String sql = "select DISTINCT o.code from users u " +
(tng) (tng) (tng) (tng) (tng) "inner join groupmember gm on u.userId=gm.user_Id " +
(tng) (tng) (tng) (tng) (tng) "inner join groupacl ga on gm.group_id=ga.group_id " +
(tng) (tng) (tng) (tng) (tng) "inner join operation o on ga.op_id = o.id " +
(tng) (tng) (tng) (tng) (tng) "where u.userId=?";
(tng) Query q = s.createSQLQuery(sql).setString(0,userId);
(tng) List<Object> ls = q.list();
(tng) HashSet ops = new HashSet();
(tng) for(Object object : ls){
(tng) (tng) ops.add(object);
(tng) }
(tng) tx.commit();
(tng) releaseSession(s);
(tng)
(tng) return ops;
(tng)}
q样Q在用户dӞ可以把该用户的权限HashSet装蝲到Session?/p>
(tng)
//把当前用L(fng)权限d到HashSet
(tng) (tng)
Java代码
HashSet ops = AppResource.operationService.findByUserId(user.getUserId()); (tng) (tng)
session.setAttribute("ops",ops); (tng)
HashSet ops = AppResource.operationService.findByUserId(user.getUserId());
session.setAttribute("ops",ops);
最后，在JSP中就可以单的使用标签来判断有没有某个权限Q没有则不显C?/p>
Xml代码
<%@ taglib prefix="psy" uri="<psy:op code="Finance_Payment">看你有没有权限让我显C?lt;/psy:op> (tng)
<%@ taglib prefix="psy" uri="<psy:op code="Finance_Payment">看你有没有权限让我显C?lt;/psy:op>
(tng)
OKQ可以根据需要修攏V?br />
]]>
package anni;
public class EncodingFilter implements Filter {
(tng) (tng) (tng) public void init(FilterConfig config) throws ServletException {}
(tng) (tng) (tng) public void destroy() {}
(tng) (tng) (tng) public void doFilter(ServletRequest request,
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) ServletResponse response,
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) FilterChain chain)
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) throws IOException, ServletException {
(tng) (tng) (tng) (tng) (tng) (tng) (tng) request.setCharacterEncoding("gb2312");
(tng) (tng) (tng) (tng) (tng) (tng) (tng) chain.doFilter(request, response);
(tng) (tng) (tng) }
}
web.xml?br /><filter>
(tng) (tng) (tng) <filter-name>EncodingFilter</filter-name>
(tng) (tng) (tng) <filter-class>anni.EncodingFilter</filter-class>
</filter>
<filter-mapping>
(tng) (tng) (tng) <filter-name>EncodingFilter</filter-name>
(tng) (tng) (tng) <url-pattern>/*</url-pattern>
</filter-mapping>
filter标签部分定义使用的过滤器Qfilter-mapping标签告诉服务器把哪些h交给qo(h)器处理。这里的/*表示所有请求，/表示根\径，*Q星P(j)代表所有请求，加在一起就变成?jin)根路径下的所有请求。这P所有的h都会(x)先被EncodingFilter拦截Qƈ在请求里讄上指定的gb2312~码?/p>
================================
用filter控制用户讉K权限
我们要保护的面是admin/index.jspQؓ(f)此我们在web.xmlq行如下配置?br /><filter>
(tng) (tng) (tng) <filter-name>SecurityFilter</filter-name>
(tng) (tng) (tng) <filter-class>anni.SecurityFilter</filter-class>
</filter>
<filter-mapping>
(tng) (tng) (tng) <filter-name>SecurityFilter</filter-name>
(tng) (tng) (tng) <url-pattern>/admin/*</url-pattern>
</filter-mapping>
SecurityFilterqo(h)?
public void doFilter(ServletRequest request,
(tng) (tng) (tng) (tng) (tng) (tng) (tng) ServletResponse response,
(tng) (tng) (tng) (tng) (tng) (tng) (tng) FilterChain chain)
(tng) (tng) (tng) (tng) (tng) (tng) (tng) throws IOException, ServletException {
(tng) (tng) (tng) HttpServletRequest req = (HttpServletRequest) request;
(tng) (tng) (tng) HttpServletResponse res = (HttpServletResponse) response;
(tng) (tng) HttpSession session = req.getSession();
(tng) (tng) (tng) if (session.getAttribute("username") != null) {
(tng) (tng) (tng) (tng) (tng) (tng) (tng) chain.doFilter(request, response);
(tng) (tng) (tng) } else {
(tng) (tng) (tng) (tng) (tng) (tng) (tng) res.sendRedirect("../failure.jsp");
(tng) (tng) (tng) }
}
首先要将ServletRequest和ServletResponse转换成HttpServletRequest和HttpServletResponseQ因为Filter本来设计成ؓ(f)多种协议服务Qhttp协议仅仅是其中一部分。不q我们接触到的也只有httpQ而且也只有{换成对应HttpServletRequest和HttpServletResponse才能q行下面的session操作和页面重定向?br />得到?jin)httph之后Q可以获得请求对应的sessionQ判断session中的username变量是否为nullQ如果不为nullQ说明用户已l登录，可以调用doFilterl箋(hu)h讉K的资源。如果ؓ(f)nullQ说明用戯没有dQ禁止用戯问，q用页面重定向跌{到failure.jsp面昄提示信息?/p>
==================================
filter所谓的Ҏ(gu)?/p>
h映射
filter-mapping和servlet-mapping都是对应的filter或servlet映射到某个url-pattern上，当客户发h一hӞ服务器先此h与web.xml中定义的所有url-patternq行匚wQ然后执行匹配通过的filter和servlet?/p>
你可以用三U方式定义url-pattern?br />1.直接映射一个请求?br /><servlet-mapping>
(tng) (tng) (tng) <servlet-name>ContactServlet</servlet-name>
(tng) (tng) (tng) <url-pattern>/contact.do</url-pattern>
</servlet-mapping>
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng)
2.映射一个\径下的所有请求?br /><servlet-mapping>
(tng) (tng) (tng) <servlet-name>EncodingFilter</servlet-name>
(tng) (tng) (tng) <url-pattern>/*</url-pattern>
</servlet-mapping>
3.映射l尾相同的一c请求?br /><servlet-mapping>
(tng) (tng) (tng) <servlet-name>ControllerServlet</servlet-name>
(tng) (tng) (tng) <url-pattern>*.do</url-pattern>
</servlet-mapping>
惌获得所有以user开?dol尾的请求吗Quser*.do在url-pattern是无法识别的Q只能配|成*.doQ再去servlet中对hq行{选?br />惌让一个servlet负责多个h吗？/user/*,/admin/*,*.do写在一起url-pattern也不认识Q只能配成多个servlet-mapping?br /><servlet-mapping>
(tng) (tng) (tng) <servlet-name>ControllerServlet</servlet-name>
(tng) (tng) (tng) <url-pattern>/user/*</url-pattern>
</servlet-mapping>
<servlet-mapping>
(tng) (tng) (tng) <servlet-name>ControllerServlet</servlet-name>
(tng) (tng) (tng) <url-pattern>/admin/*</url-pattern>
</servlet-mapping>
<servlet-mapping>
(tng) (tng) (tng) <servlet-name>ControllerServlet</servlet-name>
(tng) (tng) (tng) <url-pattern>*.do</url-pattern>
</servlet-mapping>
qo(h)?/p>
服务器会(x)按照web.xml中过滤器定义的先后@序组装成一条链Q然后一ơ执行其中的doFilter()Ҏ(gu)。执行的序如上图所C，执行W一个过滤器的chain.doFilter()之前的代码，W二个过滤器的chain.doFilter()之前的代码，h的资源，W二个过滤器的chain.doFilter()之后的代码，W一个过滤器的chain.doFilter()之后的代码，最后返回响应?br />qo(h)铄好处是，执行q程中Q何时候都可以打断Q只要不执行chain.doFilter()׃?x)再执行后面的过滤器和请求的内容。而在实际使用Ӟp特别注意qo(h)铄执行序问题Q像EncodingFilter׃定要攑֜所有Filter之前Q这h能确保在使用h中的数据前设|正的~码?/p>
filter的详l配|?/p>
在servlet-2.3中，Filter?x)过滤一切请求，包括服务器内部用forward转发h?lt;%@ include file="/index.jsp"%>的情c(din)?br />C(jin)servlet-2.4中Filter默认下只拦截外部提交的请求，forward和includeq些内部转发都不?x)被qo(h)Q但是有时候我们需要forward的时候也用到FilterQ这样就需要如下配|?br /><filter>
(tng) (tng) (tng) <filter-name>TestFilter</filtername>
(tng) (tng) (tng) <filter-class>anni.TestFilter</filter-class>
</filter>
<filter-mapping>
(tng) (tng) (tng) <filter-name>TestFilter</filtername>
(tng) (tng) (tng) <url-pattern>/*</url-pattern>
(tng) (tng) (tng) <dispatcher>REQUEST</dispatcher>
(tng) (tng) (tng) <dispatcher>FORWARD</dispatcher>
(tng) (tng) (tng) <dispatcher>INCLUDE</dispatcher>
(tng) (tng) (tng) <dispatcher>EXCEPTION</dispatcher>
</filter-mapping>
(tng) (tng) (tng) (tng) (tng) (tng) (tng)
q样TestFilter׃(x)qo(h)所有状态下的请求。如果我们没有进行设|，默认使用的就是REQUEST。而EXCEPTION是在isErrorPage="true"的情况下出现的，q个用处不多Q看一下即可?br />q里FORWARD是解决request.getDispatcher("index.jsp").forward(request, response);无法触发Filter的关键，配置上这个以后再q行forward的时候就可以触发qo(h)器了(jin)?/p>
Filterq有一个有的用法Q在filter-mapping中我们可以直接指定servlet-mappingQ让qo(h)器只处理一个定义在web.xml中的servlet?br /><filter-mapping>
(tng) (tng) (tng) <filter-name>TestFilter</filter-name>
(tng) (tng) (tng) <servlet-name>TestServlet</servlet-name>
</filter-mapping>
<servlet>
(tng) (tng) (tng) <servlet-name>TestServlet</servlet-name>
(tng) (tng) (tng) <servlet-class>anni.TestServlet</servlet-class>
</servlet>
<servlet-mapping>
(tng) (tng) (tng) <servlet-name>TestServlet</servlet-name>
(tng) (tng) (tng) <url-pattern>/TestServlet</url-pattern>
</servlet-mapping>
(tng) (tng) (tng) (tng) (tng) (tng)
直接指定servlet-nameQTestFilter便会(x)引用TestServlet配置的url-patternQ在某些filter与servletl定的情况下不失Z个好办法?/p>
(tng) (tng)
1.Listener是Servlet的监听器 (tng) (tng) (tng) (tng)
2.可以监听客户端的h、服务端的操作等。?tng) (tng)?
3.通过监听器，可以自动Ȁ发一些操作，如监听在U用h?当增加一个HttpSessionӞl在Uh数加1。?tng) (tng)?
4.~写监听器需要实现相应的接口 (tng) (tng) (tng)
5.~写完成后在web.xml文g中配|一?可以v作用?jin) (tng) (tng)?
6.可以在不修改现有pȝ基础?增加web应用E序生命周期事g的跟t?tng) (tng)?
(tng) (tng)
(tng) (tng)
常用的监听接口?tng) (tng)?
(tng) (tng)
1.ServletContextAttributeListener (tng) (tng) (tng)
监听对ServletContext属性的操作Q比如增?删除/修改 (tng) (tng) (tng)
2.ServletContextListener (tng) (tng) (tng)
监听ServletContext,当创建ServletContextӞȀ发contextInitialized(ServletContextEvent sce)Ҏ(gu)Q当销毁ServletContextӞȀ发contextDestroyed(ServletContextEvent sce)Ҏ(gu)。?tng) (tng)?
3.HttpSessionListener (tng) (tng) (tng)
监听HttpSession的操作。当创徏一个SessionӞȀ发session Created(SessionEvent se)Ҏ(gu)Q当销毁一个SessionӞȀ发sessionDestroyed (HttpSessionEvent se)Ҏ(gu)。?tng) (tng)?
4.HttpSessionAttributeListener (tng) (tng) (tng)
监听HttpSession中的属性的操作。当在Session增加一个属性时Q激发attributeAdded(HttpSessionBindingEvent se) Ҏ(gu)Q当在Session删除一个属性时Q激发attributeRemoved(HttpSessionBindingEvent se)Ҏ(gu)Q当在Session属性被重新讄ӞȀ发attributeReplaced(HttpSessionBindingEvent se) Ҏ(gu)。?tng) (tng)?
(tng) (tng)
使用范例Q?tng) (tng)?
q听器理׃n数据库连接?tng) (tng)?
(tng) (tng)
生命周期事g的一个实际应用由context监听器管理共享数据库q接。在web.xml中如下定义监听器Q?tng) (tng)?
<listener> (tng) (tng) (tng)
(tng) (tng) (tng) <listener-class>XXX.MyConnectionManager</listener-class> (tng) (tng) (tng)
</listener> ?server创徏监听器的实例,接受事gq自动判断实现监听器接口的类型。要C的是׃监听器是配置在部|描q符web.xml中，所以不需要改变(sh)Q何代码就可以d新的监听器。?tng) (tng)?
(tng) (tng)
public class MyConnectionManager implements ServletContextListener{ (tng) (tng) (tng) (tng) (tng)
public void contextInitialized(ServletContextEvent e) { (tng) (tng) (tng) (tng)
(tng) (tng) (tng) (tng) (tng) (tng) (tng) Connection con = // create connection (tng) (tng) (tng) (tng)
(tng) (tng) (tng) (tng) (tng) (tng) (tng) e.getServletContext().setAttribute("con", con); (tng) (tng) (tng) (tng)
(tng) (tng) (tng) } (tng) (tng) (tng) (tng) (tng)
(tng) (tng) public void contextDestroyed(ServletContextEvent e) { (tng) (tng) (tng) (tng)
(tng) (tng) (tng) (tng) (tng) (tng) (tng) Connection con = (Connection) e.getServletContext().getAttribute("con"); (tng) (tng) (tng) (tng)
(tng) (tng) (tng) (tng) (tng) (tng) (tng) try { (tng) (tng) (tng)
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) con.close(); (tng) (tng) (tng) (tng)
(tng) (tng) (tng) (tng) (tng) (tng) (tng) } (tng) (tng) (tng) (tng)
(tng) (tng) (tng) (tng) (tng) (tng) catch (SQLException ignored) { } // close connection (tng) (tng) (tng) (tng)
(tng) (tng) (tng) } (tng) (tng) (tng) (tng)
} (tng) (tng) (tng) (tng) (tng)
监听器保证每新生成一个servlet context都会(x)有一个可用的数据库连?q且所有的q接对会(x)在context关闭的时候随之关闭。?tng) (tng) (tng) (tng)?br /> (tng) (tng)
在web.xml中加? (tng) (tng) (tng)
<listener><listener-class>servletlistener111111.SecondListener</listener-class> </listener>
==================================================
关于用户时的例子：(x)
public class OnlineUserListener implements HttpSessionListener {
(tng) (tng) (tng) public void sessionCreated(HttpSessionEvent event) {
(tng) (tng) (tng) }
(tng) (tng) (tng) public void sessionDestroyed(HttpSessionEvent event) {
(tng) (tng) (tng) (tng) (tng) (tng) (tng) HttpSession session = event.getSession();
(tng) (tng) (tng) (tng) (tng) (tng) (tng) ServletContext application = session.getServletContext();
(tng) (tng) (tng) (tng) (tng) (tng) (tng) // 取得d的用户名
(tng) (tng) (tng) (tng) (tng) (tng) (tng) String username = (String) session.getAttribute("username");
(tng) (tng) (tng) (tng) (tng) (tng) (tng) // 从在U列表中删除用户?br /> (tng) (tng) (tng) (tng) (tng) (tng) (tng) List onlineUserList = (List) application.getAttribute("onlineUserList");
(tng) (tng) (tng) (tng) (tng) (tng) (tng) onlineUserList.remove(username);
(tng) (tng) (tng) (tng) (tng) (tng) (tng) System.out.println(username + "时退出?);
(tng) (tng) (tng) }
}
以下两种情况下就?x)发生sessionDestoryedQ会(x)话销毁）(j)事gQ?/p>
1.执行session.invalidate()Ҏ(gu)时。例如：(x)request.getSession().invalidate();
2.如果用户长时间没有访问服务器Q超q了(jin)?x)话最大超时时_(d)服务器就?x)自动销毁超时的session。会(x)话超时时间可以在web.xml中进行设|?/p>
========================================
使用HttpSessionBindingListener
HttpSessionBindingListener虽然叫做监听器，但用方法与HttpSessionListener完全不同。我们实际看一下它是如何用的?/p>
我们的OnlineUserBindingListener实现?jin)HttpSessionBindingListener接口Q接口中共定义了(jin)两个Ҏ(gu)QvalueBound()和valueUnbound()Q分别对应数据绑定，和取消绑定两个事件?/p>
所谓对sessionq行数据l定Q就是调用session.setAttribute()把HttpSessionBindingListener保存qsession中。我们在LoginServlet.java中进行这一步?/p>
// 把用户名攑օ在线列表
session.setAttribute("onlineUserBindingListener", new OnlineUserBindingListener(username));
(tng) (tng) (tng) (tng) (tng) (tng) (tng)
q就是HttpSessionBindingListener和HttpSessionListener之间的最大区别：(x)HttpSessionListener只需要设|到web.xml中就可以监听整个应用中的所有session。HttpSessionBindingListener必须实例化后攑օ某一个session中，才可以进行监听?/p>
从监听范围上比较QHttpSessionListener讄一ơ就可以监听所有sessionQHttpSessionBindingListener通常都是一对一的?/p>
正是q种区别成就?jin)HttpSessionBindingListener的优势，我们可以让每个listener对应一个usernameQ这样就不需要每ơ再去session中读取usernameQ进一步可以将所有操作在U列表的代码都移入listenerQ更Ҏ(gu)l护?/p>
valueBound()Ҏ(gu)的代码如下：(x)
public void valueBound(HttpSessionBindingEvent event) {
(tng) (tng) (tng) HttpSession session = event.getSession();
(tng) (tng) (tng) ServletContext application = session.getServletContext();
(tng) (tng) (tng) // 把用户名攑օ在线列表
(tng) (tng) (tng) List onlineUserList = (List) application.getAttribute("onlineUserList");
(tng) (tng) (tng) // W一ơ用前Q需要初始化
(tng) (tng) (tng) if (onlineUserList == null) {
(tng) (tng) (tng) (tng) (tng) (tng) (tng) onlineUserList = new ArrayList();
(tng) (tng) (tng) (tng) (tng) (tng) (tng) application.setAttribute("onlineUserList", onlineUserList);
(tng) (tng) (tng) }
(tng) (tng) (tng) onlineUserList.add(this.username);
}
(tng) (tng) (tng) (tng) (tng) (tng) (tng)
username已经通过构造方法传递给listenerQ在数据l定Ӟ可以直接把它攑օ用户列表?/p>
与之对应的valueUnbound()Ҏ(gu)Q代码如下：(x)
public void valueUnbound(HttpSessionBindingEvent event) {
(tng) (tng) (tng) HttpSession session = event.getSession();
(tng) (tng) (tng) ServletContext application = session.getServletContext();
(tng) (tng) (tng) // 从在U列表中删除用户?br /> (tng) (tng) (tng) List onlineUserList = (List) application.getAttribute("onlineUserList");
(tng) (tng) (tng) onlineUserList.remove(this.username);
(tng) (tng) (tng) System.out.println(this.username + "退出?);
}
(tng) (tng) (tng) (tng) (tng) (tng) (tng)
q里可以直接使用listener的username操作在线列表Q不必再L?j)session中是否存在username?/p>
valueUnbound的触发条件是以下三种情况Q?/p>
1.执行session.invalidate()时?/p>
2.session时Q自动销毁时?/p>
3.执行session.setAttribute("onlineUserListener", "其他对象");或session.removeAttribute("onlineUserListener");listener从session中删除时?/p>
因此Q只要不listener从session中删除，可以监听到session的销毁?/p>
|
用HttpSessionListener ?
package demo.listener; import javax.servlet.ServletContext; import javax.servlet.http.HttpSessionEvent; import javax.servlet.http.HttpSessionListener; public class SessionCounter implements HttpSessionListener { (tng) (tng) (tng) (tng) public void sessionCreated(HttpSessionEvent event) { (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) ServletContext ctx = event.getSession( ).getServletContext( ); (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) Integer numSessions = (Integer) ctx.getAttribute("numSessions"); (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) if (numSessions == null) { (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) numSessions = new Integer(1); (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) } (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) else { (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) int count = numSessions.intValue( ); (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) numSessions = new Integer(count + 1); (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) } (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) ctx.setAttribute("numSessions", numSessions); (tng) (tng) (tng) (tng) } (tng) (tng) (tng) (tng) public void sessionDestroyed(HttpSessionEvent event) { (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) ServletContext ctx = event.getSession( ).getServletContext( ); (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) Integer numSessions = (Integer) ctx.getAttribute("numSessions"); (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) if (numSessions == null) { (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) numSessions = new Integer(0); (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) } (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) else { (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) int count = numSessions.intValue( ); (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) numSessions = new Integer(count - 1); (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) } (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) ctx.setAttribute("numSessions", numSessions); (tng) (tng) (tng) (tng) } } 在这个解x(chng)案中QQ何一个Session被创建或者销毁时Q都?x)通知SessionCounter q个c，当然通知的原因是必须在web.xml文g中做相关的配|工作。如下面的配|代码：(x) <?xml version="1.0" encoding="ISO-8859-1" ?> <!DOCTYPE web-app PUBLIC (tng) (tng) (tng) (tng) "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" (tng) (tng) (tng) (tng) "http://java.sun.com/dtd/web-app_2_3.dtd"> (tng) (tng) (tng) (tng) <web-app> (tng) (tng) <display-name>Struts Examples</display-name> (tng) (tng) (tng) (tng) <listener> (tng) (tng) (tng) (tng) (tng) (tng) <listener-class>demo.listener.SessionCounter (tng) (tng) (tng) (tng) (tng) (tng) </listener-class> (tng) (tng) </listener> |
]]>
JDBCTM中Statement接口提供的execute、executeQuery和executeUpdate之间的区?
Statement 接口提供?jin)三U执?SQL 语句的方法：(x)executeQuery、executeUpdate ?execute。用哪一个方法由 SQL 语句所产生的内容决定?
Ҏ(gu)executeQuery
用于产生单个l果集的语句Q例?SELECT 语句?被用最多的执行 SQL 语句的方法是 executeQuery。这个方法被用来执行 SELECT 语句Q它几乎是用最多的 SQL 语句?
Ҏ(gu)executeUpdate
用于执行 INSERT、UPDATE ?DELETE 语句以及(qing) SQL DDLQ数据定义语aQ语句，例如 CREATE TABLE ?DROP TABLE。INSERT、UPDATE ?DELETE 语句的效果是修改表中零行或多行中的一列或多列。executeUpdate 的返回值是一个整敎ͼ指示受媄(jing)响的行数Q即更新计数Q。对?CREATE TABLE ?DROP TABLE {不操作行的语句QexecuteUpdate 的返回值Mؓ(f)零?
使用executeUpdateҎ(gu)是因为在 createTableCoffees 中的 SQL 语句?DDL Q数据定义语aQ语句。创Q改变表Q删除表都是 DDL 语句的例子，要用 executeUpdate Ҏ(gu)来执行。你也可以从它的名字里看出，Ҏ(gu) executeUpdate 也被用于执行更新?SQL 语句。实际上Q相对于创徏表来_(d)executeUpdate 用于更新表的旉更多Q因只需要创Zơ，但经常被更新?
Ҏ(gu)executeQ?
用于执行q回多个l果集、多个更新计数或二者组合的语句。因为多数程序员?sh)?x)需要该高功能
executeҎ(gu)应该仅在语句能返回多个ResultSet对象、多个更新计数或ResultSet对象与更新计数的l合时用。当执行某个已存储过E?或动态执行未?SQL 字符Ԍ卛_用程序程序员在编译时未知Q时Q有可能出现多个l果的情况，管q种情况很少见?
因ؓ(f)Ҏ(gu) execute 处理非常规情况，所以获取其l果需要一些特D处理ƈ不为怪。例如，假定已知某个q程q回两个l果集，则在使用Ҏ(gu) execute 执行该过E后Q必调用方?getResultSet 获得W一个结果集Q然后调用适当?getXXX Ҏ(gu)获取其中的倹{要获得W二个结果集Q需要先调用 getMoreResults Ҏ(gu)Q然后再调用 getResultSet Ҏ(gu)。如果已知某个过E返回两个更新计敎ͼ则首先调用方?getUpdateCountQ然后调?getMoreResultsQƈ再次调用 getUpdateCount?
对于不知道返回内容，则情冉|为复杂。如果结果是 ResultSet 对象Q则Ҏ(gu) execute q回 trueQ如果结果是 Java intQ则q回 false。如果返?intQ则意味着l果是更新计数或执行的语句是 DDL 命o(h)。在调用Ҏ(gu) execute 之后要做的第一件事情是调用 getResultSet ?getUpdateCount。调用方?getResultSet 可以获得两个或多?ResultSet 对象中第一个对象；或调用方?getUpdateCount 可以获得两个或多个更新计CW一个更新计数的内容?
?SQL 语句的结果不是结果集Ӟ则方?getResultSet 返?null。这可能意味着l果是一个更新计数或没有其它l果。在q种情况下，判断 null 真正含义的唯一Ҏ(gu)是调用方?getUpdateCountQ它?yu)返回一个整数。这个整Cؓ(f)调用语句所影响的行敎ͼ如果?-1 则表C结果是l果集或没有l果。如果方?getResultSet 已返?nullQ表C结果不?ResultSet 对象Q，则返回?-1 表示没有其它l果。也是_(d)当下列条件ؓ(f)真时表示没有l果Q或没有其它l果Q：(x)
((stmt.getResultSet() == null) && (stmt.getUpdateCount() == -1))
如果已经调用Ҏ(gu) getResultSet q处理了(jin)它返回的 ResultSet 对象Q则有必要调用方?getMoreResults 以确定是否有其它l果集或更新计数。如?getMoreResults q回 trueQ则需要再ơ调?getResultSet 来检索下一个结果集。如上所qͼ如果 getResultSet q回 nullQ则需要调?getUpdateCount 来检?null 是表C结果ؓ(f)更新计数q是表示没有其它l果?
?getMoreResults q回 false Ӟ它表C SQL 语句q回一个更新计数或没有其它l果。因此需要调用方?getUpdateCount 来检查它是哪一U情c(din)在q种情况下，当下列条件ؓ(f)真时表示没有其它l果Q?
((stmt.getMoreResults() == false) && (stmt.getUpdateCount() == -1))
下面的代码演CZ(jin)一U方法用来确认已讉K调用Ҏ(gu) execute 所产生的全部结果集和更新计敎ͼ(x)
stmt.execute(queryStringWithUnknownResults);
while (true) {
int rowCount = stmt.getUpdateCount();
if (rowCount > 0) { // 它是更新计数
System.out.println("Rows changed = " + count);
stmt.getMoreResults();
continue;
}
if (rowCount == 0) { // DDL 命o(h)?0 个更?
System.out.println(" No rows changed or statement was DDL
command");
stmt.getMoreResults();
continue;
}
// 执行到这里，证明有一个结果集
// 或没有其它结?
ResultSet rs = stmt.getResultSet;
if (rs != null) {
. . . // 使用元数据获得关于结果集列的信息
while (rs.next()) {
. . . // 处理l果
stmt.getMoreResults();
continue;
}
break; // 没有其它l果
]]>
(tng)import="java.util.*" pageEncoding="GBK"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GBK">
<title>Insert title here</title>
</head>
<body>
<%
out.print("<br>"+"session is new:"+session.isNew());
Date created = new Date(session.getCreationTime());
//得到session对象创徏的时?br />Date accessed = new Date(session.getLastAccessedTime());
//得到最后访问该session对象的时?br />out.println("<br>"+"ID " + session.getId()+" ");
//得到该session的idQƈ打印
out.println("<br>"+"Created: " + created+" ");
//打印session创徏旉
out.println("<br>"+"Last Accessed: " + accessed+" ");
//打印最后访问时?/p>
session.setAttribute("Name","Tom");
//在session中添加变量Name=Tom
session.setAttribute("UID","12345678");
//在session中添加变量UID=12345678
Enumeration e = session.getAttributeNames();
//得到session中变量名的枚丑֯?br />while (e.hasMoreElements()) { //遍历每一个变?br />String name = (String)e.nextElement(); //首先得到名字
String value = session.getAttribute(name).toString();
//由名字从session中得到?br />out.println("<br>"+name + " = " + value+" "); //打印
}
%>
</body>
</html>
]]>
1、uploadimage.jsp
<%@ page contentType="text/html;charset=gb2312" language="java" import="java.io.*,java.awt.Image,java.awt.image.*,com.sun.image.codec.jpeg.*,
java.sql.*,com.jspsmart.upload.*,java.util.*,cn.oof.database.*,cn.oof.house.*"%>
<%
SmartUpload mySmartUpload =new SmartUpload();
long file_size_max=4000000;
String fileName2="",ext="",testvar="";
String url="uploadfile/images/"; (tng) (tng) (tng) (tng) (tng) (tng) //应保证在根目录中有此目录的存?br />//初始?br />mySmartUpload.initialize(pageContext);
//只允怸载此cL?br />try {
mySmartUpload.setAllowedFilesList("jpg,gif");
//上蝲文g
mySmartUpload.upload();
} catch (Exception e){
%>
(tng) (tng) <SCRIPT language=javascript>
(tng) (tng) alert("只允怸?jpg?gifcd囄文g");
(tng) (tng) window.location=''upfile.jsp'';
(tng) (tng) </script>
<%
}
try{
(tng) (tng) (tng) (tng) com.jspsmart.upload.File myFile = mySmartUpload.getFiles().getFile(0);
(tng) (tng) (tng) (tng) if (myFile.isMissing()){%>
(tng) (tng) (tng) <SCRIPT language=javascript>
(tng) (tng) (tng) alert("请先选择要上传的文g");
(tng) (tng) (tng) window.location=''upfile.jsp'';
(tng) (tng) (tng) </script>
(tng) (tng) (tng) (tng) <%}
(tng) (tng) (tng) (tng) else{
(tng) (tng) (tng) (tng) (tng) (tng) //String myFileName=myFile.getFileName(); //取得上蝲的文件的文g?br /> (tng) (tng) (tng) ext= myFile.getFileExt(); (tng) (tng) (tng) (tng) (tng) (tng) //取得后缀?br /> (tng) (tng) (tng) int file_size=myFile.getSize(); (tng) (tng) (tng) (tng) (tng) //取得文g的大?tng)?br /> (tng) (tng) (tng) String saveurl="";
(tng) (tng) (tng) if(file_size<file_size_max){
(tng) (tng) (tng) (tng) //更改文g名，取得当前上传旉的毫U数?br /> (tng) (tng) (tng) (tng) Calendar calendar = Calendar.getInstance();
(tng) (tng) (tng) (tng) String filename = String.valueOf(calendar.getTimeInMillis());
(tng) (tng) (tng) (tng) saveurl=request.getRealPath("/")+url;
(tng) (tng) (tng) (tng) saveurl+=filename+"."+ext; (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) //保存路径
(tng) (tng) (tng) (tng) myFile.saveAs(saveurl,mySmartUpload.SAVE_PHYSICAL);
(tng) (tng) (tng) (tng) //out.print(filename);
//-----------------------上传完成Q开始生成羃略图------------------------- (tng) (tng) (tng) (tng)
(tng) (tng) (tng) (tng) java.io.File file = new java.io.File(saveurl); (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) //d刚才上传的文?br /> (tng) (tng) (tng) (tng) String newurl=request.getRealPath("/")+url+filename+"_min."+ext; (tng) (tng) //新的~略图保存地址
(tng) (tng) (tng) (tng) Image src = javax.imageio.ImageIO.read(file); (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) //构造I(yng)mage对象
(tng) (tng) (tng) (tng) float tagsize=200;
(tng) (tng) (tng) (tng) int old_w=src.getWidth(null); (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) //得到源图?br /> (tng) (tng) (tng) (tng) int old_h=src.getHeight(null); (tng) (tng) (tng)
(tng) (tng) (tng) (tng) int new_w=0;
(tng) (tng) (tng) (tng) int new_h=0; (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) //得到源图?br /> (tng) (tng) (tng) (tng) int tempsize;
(tng) (tng) (tng) (tng) float tempdouble;
(tng) (tng) (tng) (tng) if(old_w>old_h){
(tng) (tng) (tng) (tng) (tng) tempdouble=old_w/tagsize;
(tng) (tng) (tng) (tng) }else{
(tng) (tng) (tng) (tng) (tng) tempdouble=old_h/tagsize;
(tng) (tng) (tng) (tng) }
(tng) (tng) (tng) (tng) new_w=Math.round(old_w/tempdouble);
(tng) (tng) (tng) (tng) new_h=Math.round(old_h/tempdouble);//计算新图长宽
(tng) (tng) (tng) (tng) BufferedImage tag = new BufferedImage(new_w,new_h,BufferedImage.TYPE_INT_RGB);
(tng) (tng) (tng) (tng) tag.getGraphics().drawImage(src,0,0,new_w,new_h,null); (tng) (tng) (tng) (tng) (tng) (tng) (tng) //l制~小后的?br /> (tng) (tng) (tng) (tng) FileOutputStream newimage=new FileOutputStream(newurl); (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) //输出到文件流
(tng) (tng) (tng) (tng) JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(newimage); (tng) (tng) (tng) (tng) (tng) (tng) (tng)
(tng) (tng) (tng) (tng) encoder.encode(tag); (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) //qJPEG~码
(tng) (tng) (tng) (tng) (tng) newimage.close(); (tng) (tng) (tng) (tng)
(tng) (tng) (tng) }
(tng) (tng) (tng) else{
(tng) (tng) (tng) (tng) out.print("<SCRIPT language=''javascript''>");
(tng) (tng) (tng) (tng) out.print("alert(''上传文g大小不能过"+(file_size_max/1000)+"K'');");
(tng) (tng) (tng) (tng) out.print("window.location=''upfile.jsp;''");
(tng) (tng) (tng) (tng) out.print("</SCRIPT>");
(tng) (tng) (tng) }
(tng) (tng) }
}catch (Exception e){
e.toString();
}
%>
2 upload.htm
<html>
<head>
<title>请选择上传的图?lt;/title>
</head>
<body>
<table border="0" align="center" cellpadding="0" cellspacing="0">
(tng) (tng) <tr>
(tng) (tng) (tng) (tng) <td height="45" align="center" valign="middle"><form action="uploadimage.jsp" method="post" enctype="multipart/form-data" name="form1">
请选择上传的图?br /> (tng) (tng) (tng) (tng) <input type="file" name="file">
<input type="submit" name="Submit" value="上传">
(tng) (tng) (tng) (tng) </form></td>
(tng) (tng) </tr>
</table>
</body>
</html>
]]>
数据库应用程序，特别是基于WEB的数据库应用E序Q常?x)涉及(qing)到囄信息的存储和昄。通常我们使用的方法是所要显C的囄存在特定的目录下Q在数据库中保存相应的图片的名称Q在JSP中徏立相应的数据源，利用数据库访问技术处理图片信息。但是，如果我们惛_态的昄囄Q上q方法就不能满需要了(jin)。我们必L囄存入数据库，然后通过~程动态地昄我们需要的囄。实际操作中Q可以利用JSP的编E模式来实现囄的数据库存储和显C?
2、徏立后台数据库
假定处理的是囄新闻Q那么我们可以徏立相应的数据库及(qing)数据表对象。我们要存取的数据表l构的SQL脚本如下所C：(x)
if exists (select * from dbo.sysobjects where id =
object_id(N'[dbo].[picturenews]') andOBJECTPROPERTY(id, N'IsUserTable') = 1)
drop table [dbo].[picturenews]
GO
CREATE TABLE [dbo].[picturenews] (
[id] [int] IDENTITY (1, 1) NOT NULL ,
[image] [image] NULL ,
[content] [varchar] (500) COLLATE Chinese_PRC_CI_AS NULL ,
[detail] [varchar] (5000) COLLATE Chinese_PRC_CI_AS NULL
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
GO
表picturenews中，字段id作ؓ(f)标识Q每存储一行数据，自动增加1。字Dimage
用于存储囄信息Q其数据cd为“image”?
3、向数据库存储二q制囄
启动Dreamweaver MX后，新徏一个JSP文g。其代码如下所C?
<%@ page contentType="text/html;charset=gb2312"%>
<HTML>
<HEAD>
<TITLE>存储囄</TITLE>
</HEAD>
<body>
<!-- 下面的窗体将以PostҎ(gu)Q将数据传递给testimage.jsp文g -->
<FORM METHOD=POST ACTION="testimage.jsp">
???题：(x)<INPUT TYPE="text" NAME="content"><BR>
???片：(x)<INPUT TYPE="file" NAME="image"><BR>
新闻内容Q?br /><TEXTAREA name="txtmail" rows="15" cols="90"
style="BORDER-BOTTOM: #000000 1px solid; BORDER-LEFT: #000000 1px solid;
BORDER-RIGHT: #000000 1px solid; BORDER-TOP: #000000 1px solid; FONT-SIZE: 9pt;
HEIGHT: 200px; WIDTH: 100%" wrap="physical" ></TEXTAREA><br>
<INPUT TYPE="submit"></form>
</body>
</HTML>
此文g保存?sh)InputImage.jsp文gQ其中testimage.jsp文g是用来将囄数据存入数据库的Q具体代码如下所C：(x)
<%@ page contentType="text/html;charset=gb2312"%>
<%@ page import="java.sql.*" %>
<%@ page import="java.util.*"%>
<%@ page import="java.text.*"%>
<%@ page import="java.io.*"%>
<html>
<body>
<%
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
//加蝲驱动E序c?br />Connection con=DriverManager.getConnection("jdbc:odbc:denglu","sa","sa");
//建立数据库联机，其中denglu为数据库名，sa接数据库的帐号及(qing)密码?br />Statement stmt=con.createStatement();
//建立Statement对象
String content=request.getParameter("content");
content=new String(content.getBytes("8859_1"),"gb2312");
String filename=request.getParameter("image");
filename=new String(filename.getBytes("8859_1"),"gb2312");
String detail=request.getParameter("txtmail");
detail=new String(detail.getBytes("8859_1"),"gb2312");
//获得所要显C图片的标题、存储\径、内容，q进行中文编?br />FileInputStream str=new FileInputStream(filename);
String sql="insert into picturenews(content,image,detail) values(?,?,?)";
PreparedStatement pstmt=con.prepareStatement(sql);
pstmt.setString(1,content);
pstmt.setBinaryStream(2,str,str.available());
pstmt.setString(3,detail);
pstmt.execute();
//数据存入数据库
out.println("Success,You Have Insert an Image Successfully");
%>
4、网中动态显C图?
接下来我们要~程从数据库中取出图片，其代码如下所C?
<%@ page contentType="text/html;charset=gb2312"%>
<%@ page import="java.sql.*" %>
<%@ page import="java.util.*"%>
<%@ page import="java.text.*"%>
<%@ page import="java.io.*"%>
<html>
<body>
<%
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
//加蝲驱动E序c?br />Connection con=DriverManager.getConnection("jdbc:odbc:denglu","sa","sa");
Statement stmt=con.createStatement();
ResultSet rs=null;
//建立ResultSetQ结果集Q对?br />int id= Integer.parseInt(request.getParameter("id"));
//获得所要显C图片的~号idQƈ转换为整?br />String sql = "select image from picturenews WHERE id="+id+"";
//要执行查询的SQL语句
rs=stmt.executeQuery(sql);
while(rs.next()) {
ServletOutputStream sout = response.getOutputStream();
//囄输出的输出流
InputStream in = rs.getBinaryStream(1);
byte b[] = new byte[0x7a120];
for(int i = in.read(b); i != -1;)
{
sout.write(b);
//缓冲区的输入输出到面
in.read(b);
}
sout.flush();
//输入完毕Q清除缓?br />sout.close();
}
%>
</body>
</html>
此文g保存?sh)testimageout.jsp文g。下一步要做的工作是使用HTML标记Q?
<IMG src="testimageout.jsp?id=<%=rs.getInt("id")%>" width=100 height=100>
取出所要显C的囄Q其中id是所要取出图片的~号。本例中我们输出?jin)第一个和最后一个图片信息，详细的程序代码如下所C?
<%@ page contentType="text/html;charset=gb2312"%>
<%@ page import="java.sql.*" %>
<html>
<head>
<title>动态显C数据库囄</title>
</head>
<body>
<%
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
Connection con=DriverManager.getConnection("jdbc:odbc:denglu","sa","sa");
Statement stmt=con.createStatement();
String sql=new String();
sql= "select * from picturenews";
ResultSet rs=stmt.executeQuery(sql);
rs.last();
//指针移x(chng)后一条记?br />%>
<table>
<tr><td><IMG height=99 src="testimageout.jsp?id=1" width=136></td>
//取出W一个图?br /><td><IMG height=99 src="testimageout.jsp?id=<%=rs.getInt("id")%>" width=136></td>
//取出最后一个图?br /></tr></table>
</body>
</html>
]]>
]]>
<%
(tng)//分页昄
(tng)int num = 0;
(tng)int countall = infolist.size();//L
(tng)int pageSize = 28;//每页数量
(tng)int pageCount;//d|
(tng)int pageNo = 1;//当前号
(tng)int mixNum; (tng) (tng) //当前|据开始号
(tng)int maxNum;
(tng)
(tng)String pNO = request.getParameter("pageNo");
(tng)if((pNO != null) && (!pNO.equals(""))){
(tng) (tng)pageNo=Integer.parseInt(pNO);
(tng)}
(tng)if (countall > pageSize) {
(tng) (tng)if ((countall / pageSize) * pageSize < countall) {
(tng) (tng) (tng)pageCount = (countall / pageSize) + 1;
(tng) (tng)}
(tng) (tng)else{
(tng) (tng) (tng)pageCount = (countall / pageSize);
(tng) (tng)}
(tng)}
(tng)
(tng)else if (countall / pageSize == 1) {
(tng) (tng)pageCount = 1;
(tng)}
(tng)else {
(tng) (tng)pageCount = 1;
(tng)}
(tng)if (pageNo >= pageCount) {
(tng) (tng)pageNo = pageCount;
(tng)}
(tng)else if (pageNo < 1) {
(tng) (tng)pageNo = 1;
(tng)}
(tng) (tng) (tng) (tng)
(tng) (tng) (tng) (tng)
(tng)mixNum = (pageNo-1) * pageSize;
(tng)maxNum = pageNo*pageSize;
(tng)
(tng)if((mixNum + pageSize) > countall){
(tng) (tng)maxNum = countall;
(tng)}
(tng)else{
(tng) (tng)maxNum = mixNum+pageSize;
(tng)}
%>
---------------------------------------------------------------------------------------------
<html>
<head>
<script language="JavaScript" type="text/JavaScript">
function check(){
(tng)if(Jtrim(document.forms.meslistForm.textfield.value)==""){
(tng) (tng)alert("误入页?);
(tng)}
(tng)else if(checkNum(document.forms.meslistForm.textfield.value)){
(tng) (tng)window.location.href="?pageNo="+document.forms.meslistForm.textfield.value;
(tng)}else{
(tng) (tng)alert("误入数字?);
(tng)}
(tng)document.forms.meslistForm.textfield.value = "";
(tng)document.forms.meslistForm.textfield.select();
}
function checkNum(str){
return str.match(/\D/)==null;
}
function Jtrim(str)
{
(tng) (tng) (tng) (tng) (tng) (tng) (tng) var i = 0;
(tng) (tng) (tng) (tng) (tng) (tng) (tng) var len = str.length;
(tng) (tng) (tng) (tng) (tng) (tng) (tng) if ( str == "" ) return( str );
(tng) (tng) (tng) (tng) (tng) (tng) (tng) j = len -1;
(tng) (tng) (tng) (tng) (tng) (tng) (tng) flagbegin = true;
(tng) (tng) (tng) (tng) (tng) (tng) (tng) flagend = true;
(tng) (tng) (tng) (tng) (tng) (tng) (tng) while ( flagbegin == true && i< len)
(tng) (tng) (tng) (tng) (tng) (tng) (tng) {
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) if ( str.charAt(i) == " " )
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) {
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) i=i+1;
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) flagbegin=true;
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) }
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) else
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) {
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) flagbegin=false;
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) }
(tng) (tng) (tng) (tng) (tng) (tng) (tng) }
(tng) (tng) (tng) (tng) (tng) (tng) (tng) while (tng) (flagend== true && j>=0)
(tng) (tng) (tng) (tng) (tng) (tng) (tng) {
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) if (str.charAt(j)==" ")
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) {
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) j=j-1;
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) flagend=true;
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) }
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) else
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) {
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) flagend=false;
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) }
(tng) (tng) (tng) (tng) (tng) (tng) (tng) }
(tng) (tng) (tng) (tng) (tng) (tng) (tng) if ( i > j ) return ("")
(tng) (tng) (tng) (tng) (tng) (tng) (tng) trimstr = str.substring(i,j+1);
(tng) (tng) (tng) (tng) (tng) (tng) (tng) return trimstr;
}</script>
</head>
<body>
<%
(tng)for(int i=mixNum;i<maxNum;i++){
(tng)//此处用list循环下标用i
(tng)} (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng)
%>
(tng)
(tng)
(tng)
(tng)
(tng)<table align="center" width="100%" border="0" cellspacing="0" cellpadding="0">
(tng) (tng) (tng)<tr>
(tng) (tng) (tng) (tng)<td width="4%" height="27" align="center" valign="middle"
(tng) (tng) (tng) (tng) (tng)class="word"> </td>
(tng) (tng) (tng) (tng)<td width="56%" align="center" valign="middle" class="word"><img
(tng) (tng) (tng) (tng) (tng)src="<%=path%>/images/pagination/list_home.gif" width="13"
(tng) (tng) (tng) (tng) (tng)height="13"> <%
(tng) (tng) (tng) (tng) (tng) (tng)if (pageNo > 1) {
(tng) (tng) (tng) (tng) (tng)%> <a href="?pageNo=1"> 首页</a>
(tng) (tng) (tng) (tng)<%
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng)}else{
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) %> 首页 <%
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng)}
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) %> <img src="<%=path%>/images/pagination/list_pre.gif"
(tng) (tng) (tng) (tng) (tng)width="13" height="13"> <%
(tng) (tng) (tng) (tng) (tng) (tng)if (pageNo > 1) {
(tng) (tng) (tng) (tng) (tng)%> <a href="?pageNo=<%=(pageNo-1)%>"> 前一?lt;/a>
(tng) (tng) (tng) (tng)<%
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng)}else{
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) %> 前一?amp;nbsp; <%
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng)}
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) %> <img
(tng) (tng) (tng) (tng) (tng)src="<%=path%>/images/pagination/list_next.gif" width="13"
(tng) (tng) (tng) (tng) (tng)height="13"> <%
(tng) (tng) (tng) (tng) (tng) (tng)if (pageCount>pageNo) {
(tng) (tng) (tng) (tng) (tng)%> <a href="?pageNo=<%=(pageNo+1)%>"> 后一?lt;/a>
(tng) (tng) (tng) (tng)<%
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng)}else{
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) %> 后一?amp;nbsp; <%
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng)} (tng)
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) %> <img src="<%=path%>/images/pagination/list_end.gif"
(tng) (tng) (tng) (tng) (tng)width="13" height="13"> <%
(tng) (tng) (tng) (tng) (tng) (tng)if (pageCount>pageNo) {
(tng) (tng) (tng) (tng) (tng)%> <a href="?pageNo=<%=(pageCount)%>"> N</a> <%
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng)}else{
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) %> N <%
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng)} (tng)
(tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) (tng) %>
(tng) (tng) (tng) (tng)<td width="26%" align="center" valign="middle" class="word">?lt;%=pageCount%>?amp;nbsp;W?lt;%=pageNo%>?amp;nbsp;
(tng) (tng) (tng) (tng)跌{</td>
(tng) (tng) (tng) (tng)<td width="4%" align="center" valign="middle" class="word"><input
(tng) (tng) (tng) (tng) (tng)name="textfield" type="text" class="input" size="1"></td>
(tng) (tng) (tng) (tng)<td width="6%" align="center" valign="middle" class="word"><a
(tng) (tng) (tng) (tng) (tng)href="javascript:check()"><img
(tng) (tng) (tng) (tng) (tng)src="<%=path%>/images/pagination/go.gif" border="0" width="18"
(tng) (tng) (tng) (tng) (tng)height="18"></a></td>
(tng) (tng) (tng) (tng)<td width="4%" align="left" valign="middle" class="word"> </td>
(tng) (tng) (tng)</tr>
(tng) (tng)</table></body> (tng) (tng)
</html>
]]>