"MSXML2.DOMDocument.4.0"," MSXML2.DOMDocument.3.0",
"MSXML2.DOMDocument"," Microsoft.XmlDom"
];
for (var i = 0; i < aVersions.length; i++) {
try {
var oXmlDom = new ActiveXObject(aVersions[i]);
return oXmlDom;
} catch (oError) {
//Do nothing
}
}
throw new Error("MSXML is not installed.");
}
浣跨敤濡備笅錛?br /> var oXmlDom = createDocument();
]]>
return new XMLHttpRequest();
} else if (window.ActiveXObject) {
var aVersions = [ "MSXML2.XMLHttp.5.0",
"MSXML2.XMLHttp.4.0","MSXML2.XMLHttp.3.0",
"MSXML2.XMLHttp","Microsoft.XMLHttp"
];
for (var i = 0; i < aVersions.length; i++) {
try {
var oXmlHttp = new ActiveXObject(aVersions[i]);
return oXmlHttp;
} catch (oError) {
//Do nothing
}
}
}
throw new Error("XMLHttp object could be created.");
}
浣跨敤濡備笅錛?br /> var oXmlHttp = createXMLHttp() 錛?
]]>
Another disadvantage, which applies to Internet Explorer only, is that you depend on ActiveX controls being enabled. If the user has your page set up in a particular security zone that doesn't allow ActiveX controls, you cannot access the XMLHttp object. In that case, you may have to default to using hidden frames.
]]>
One of the biggest arguments for using hidden frames is that you can maintain the browser history and thus enable users to still use the Back and Forward buttons in the browser. Because the browser doesn't know that a hidden frame is, in fact, hidden, it keeps track of all the requests made through it. Whereas the main page of an Ajax application may not change, the changes in the hidden frame mean that the Back and Forward buttons will move through the history of that frame instead of the main page. This technique is used in both Gmail and Google Maps for this very reason.
The downside of hidden frames is that there is very little information about what's going on behind the scenes. You are completely reliant on the proper page being returned. The examples in this section all had the same problem: If the hidden frame page failed to load, there is no notification to the user that a problem has occurred; the main page will continue to wait until the appropriate JavaScript function is called. You may be able to provide some comfort to a user by setting a timeout for a long period of time, maybe five minutes, and displaying a message if the page hasn't loaded by then, but that's just a workaround. The main problem is that you don't have enough information about the HTTP request that is happening behind the scenes. Fortunately, there is another option.
]]>
鍋氶」鐩粡甯歌鐢ㄥ埌鐨?鐜板湪鍙粰鍑轟竴涓笉鐢ㄦ暟鎹簱鐨勪唬鐮?鍙綔鍙傝?
/**
*category.jsp 鍚湁AJAX紼嬪簭
*
*/
[java]
<%@ page language="java" pageEncoding="UTF-8"%>
<html>
<head>
<title>浜岀駭鑿滃崟鑱斿姩婕旂ず</title>
<script type="text/javascript">
var req;
window.onload=function(){//欏甸潰鍔犺澆鏃剁殑鍑芥暟
}
function Change_Select(){//褰撶涓涓笅鎷夋鐨勯夐」鍙戠敓鏀瑰彉鏃惰皟鐢ㄨ鍑芥暟
var zhi = document.getElementById('hero').value;
var url = "servlet/select?id="+ escape(zhi);
if(window.XMLHttpRequest){
req = new XMLHttpRequest();
}else if(window.ActiveXObject){
req = new ActiveXObject("Microsoft.XMLHTTP");
}
if(req){
req.open("GET",url,true);
req.onreadystatechange = callback; //鎸囧畾鍥炶皟鍑芥暟涓篶allback
req.send(null);
}
}
function callback(){
if(req.readyState ==4){
if(req.status ==200){
parseMessage();//瑙ｆ瀽XML鏂囨。
}else{
alert("Not able to retrieve description" + req.statusText);
}
}
}
function parseMessage(){
var xmlDoc = req.responseXML.documentElement;//鑾峰緱榪斿洖鐨刋ML鏂囨。
var xSel = xmlDoc.getElementsByTagName('select');
//鑾峰緱XML鏂囨。涓殑鎵鏈?lt;select>鏍囪
var select_root = document.getElementById('skill');
//鑾峰緱緗戦〉涓殑絎簩涓笅鎷夋
select_root.options.length=0;
//姣忔鑾峰緱鏂扮殑鏁版嵁鐨勬椂鍊欏厛鎶婃瘡浜屼釜涓嬫媺妗嗘灦鐨勯暱搴︽竻0
for(var i=0;i<xSel.length;i++){
var xValue = xSel[i].childNodes[0].firstChild.nodeValue;
//鑾峰緱姣忎釜<select>鏍囪涓殑絎竴涓爣璁扮殑鍊?涔熷氨鏄?lt;value>鏍囪鐨勫?br> var xText = xSel[i].childNodes[1].firstChild.nodeValue;
//鑾峰緱姣忎釜<select>鏍囪涓殑絎簩涓爣璁扮殑鍊?涔熷氨鏄?lt;text>鏍囪鐨勫?br>
var option = new Option(xText, xValue);
//鏍規嵁姣忕粍value鍜宼ext鏍囪鐨勫煎垱寤轟竴涓猳ption瀵硅薄
try{
select_root.add(option);//灝唎ption瀵硅薄娣誨姞鍒扮浜屼釜涓嬫媺妗嗕腑
}catch(e){
}
}
}
</script>
</head>
<body>
<div align="center">
<form name="form1" method="post" action="">
<table width="70%" border="0" cellspacing="0" cellpadding="0">
<tr>
<td align="center">Double Select Box</td>
</tr>
<tr>
<td>
<select name="hero" id="hero" onChange="Change_Select()">
<!--絎竴涓笅鎷夎彍鍗?->
<option value="0">Unbounded</option>
<option value="1">D.K. </option>
<option value="2">NEC. </option>
<option value="3">BOSS </option>
</select>
<select name="skill" id="skill">
<!--絎簩涓笅鎷夎彍鍗?->
<option value="0">Unbounded</option>
</select>
</td>
</tr>
<tr>
<td> </td>
<tr>
</table>
</form>
</div>
</body>
</html>
[/java]
2007-3-27 15:00 bufegar
/**
*SelectServelet.java 澶勭悊欏甸潰榪斿洖鐨勬暟鎹?榪斿洖XML緇橝JAX浣跨敤
*
*/
[java]
package onlinetest.servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class SelectServlet extends HttpServlet {
/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/xml");
response.setHeader("Cache-Control", "no-cache");
String targetId = request.getParameter("id").toString();
// 鑾峰緱璇鋒眰涓弬鏁頒負id鐨勫?br> String xml_start = "<selects>";
String xml_end = "</selects>";
String xml = "";
if (targetId.equalsIgnoreCase("0")) {
xml = "<select><value>0</value><text>Unbounded</text></select>";
} else if (targetId.equalsIgnoreCase("1")) {
xml = "<select><value>1</value><text>Mana Burn</text></select>";
xml += "<select><value>2</value><text>Death Coil</text></select>";
xml += "<select><value>3</value><text>Unhkly Aura</text></select>";
xml += "<select><value>4</value><text>Unholy Fire</text></select>";
} else if (targetId.equalsIgnoreCase("2")) {
xml = "<select><value>1</value><text>Corpexplode</text></select>";
xml += "<select><value>2</value><text>Raise Dead</text></select>";
xml += "<select><value>3</value><text>Brilliance Aura</text></select>";
xml += "<select><value>4</value><text>Aim Aura</text></select>";
} else {// 濡傛灉鏄?,鍒欒繑鍥炰笅闈㈢殑瀛楃
xml = "<select><value>1</value><text>Rain of Chaos</text></select>";
xml += "<select><value>2</value><text>Finger of Death</text></select>";
xml += "<select><value>3</value><text>Bash</text></select>";
xml += "<select><value>4</value><text>Summon Doom</text></select>";
}
String last_xml = xml_start + xml + xml_end;
response.getWriter().write(last_xml);
}
/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to
* post.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);// 瀵逛簬post鐨勮姹傛柟寮忓拰get璇鋒眰鏂瑰紡涓鏍峰鐞?br> }
}
[/java]
*SelectServelet.java 澶勭悊欏甸潰榪斿洖鐨勬暟鎹?榪斿洖XML緇橝JAX浣跨敤
*
*/
[java]
package onlinetest.servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class SelectServlet extends HttpServlet {
/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/xml");
response.setHeader("Cache-Control", "no-cache");
String targetId = request.getParameter("id").toString();
// 鑾峰緱璇鋒眰涓弬鏁頒負id鐨勫?br> String xml_start = "<selects>";
String xml_end = "</selects>";
String xml = "";
if (targetId.equalsIgnoreCase("0")) {
xml = "<select><value>0</value><text>Unbounded</text></select>";
} else if (targetId.equalsIgnoreCase("1")) {
xml = "<select><value>1</value><text>Mana Burn</text></select>";
xml += "<select><value>2</value><text>Death Coil</text></select>";
xml += "<select><value>3</value><text>Unhkly Aura</text></select>";
xml += "<select><value>4</value><text>Unholy Fire</text></select>";
} else if (targetId.equalsIgnoreCase("2")) {
xml = "<select><value>1</value><text>Corpexplode</text></select>";
xml += "<select><value>2</value><text>Raise Dead</text></select>";
xml += "<select><value>3</value><text>Brilliance Aura</text></select>";
xml += "<select><value>4</value><text>Aim Aura</text></select>";
} else {// 濡傛灉鏄?,鍒欒繑鍥炰笅闈㈢殑瀛楃
xml = "<select><value>1</value><text>Rain of Chaos</text></select>";
xml += "<select><value>2</value><text>Finger of Death</text></select>";
xml += "<select><value>3</value><text>Bash</text></select>";
xml += "<select><value>4</value><text>Summon Doom</text></select>";
}
String last_xml = xml_start + xml + xml_end;
response.getWriter().write(last_xml);
}
/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to
* post.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);// 瀵逛簬post鐨勮姹傛柟寮忓拰get璇鋒眰鏂瑰紡涓鏍峰鐞?br> }
}
[/java]
2007-3-27 15:02 bufegar
/**
*web.xml 閰嶇疆Servlet,鍙互浣跨敤MyEclipse鍒涘緩Servlet,鑷姩鐢熸垚web.xml
*
*/
[xml]
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="<a target="_blank">[url]http://java.sun.com/xml/ns/j2ee[/url]"</a> xmlns:xsi="<a target="_blank">[url]http://www.w3.org/2001/XMLSchema-instance[/url]"</a> version="2.4" xsi:schemaLocation="<a target="_blank">[url]http://java.sun.com/xml/ns/j2ee[/url]</a> <a target="_blank">[url]http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd[/url]"></a>
<servlet>
<servlet-name>select</servlet-name>
<servlet-class>onlinetest.servlet.SelectServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>select</servlet-name>
<url-pattern>/servlet/select</url-pattern>
</servlet-mapping>
<filter>
<filter-name>characterFilter</filter-name>
<filter-class>filters.SetCharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>utf-8</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>characterFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>[/xml]
鍘熸枃鍦板潃:[url]http://my.boolean.cn/read.php?130&part=3[/url]
*web.xml 閰嶇疆Servlet,鍙互浣跨敤MyEclipse鍒涘緩Servlet,鑷姩鐢熸垚web.xml
*
*/
[xml]
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="<a target="_blank">[url]http://java.sun.com/xml/ns/j2ee[/url]"</a> xmlns:xsi="<a target="_blank">[url]http://www.w3.org/2001/XMLSchema-instance[/url]"</a> version="2.4" xsi:schemaLocation="<a target="_blank">[url]http://java.sun.com/xml/ns/j2ee[/url]</a> <a target="_blank">[url]http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd[/url]"></a>
<servlet>
<servlet-name>select</servlet-name>
<servlet-class>onlinetest.servlet.SelectServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>select</servlet-name>
<url-pattern>/servlet/select</url-pattern>
</servlet-mapping>
<filter>
<filter-name>characterFilter</filter-name>
<filter-class>filters.SetCharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>utf-8</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>characterFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>[/xml]
鍘熸枃鍦板潃:[url]http://my.boolean.cn/read.php?130&part=3[/url]
]]>