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Spring JDBC Framework详解——批量JDBC操作、ORM映射

�I�白 — Tue, 10 May 2011 13:06:00 GMT

作者：niumd�Q��{载请注明出处�Q�谢�?nbsp;

发表旉��Q?010 �q?nbsp;03 �?nbsp;17 �?nbsp;

原文链接�Q?a mce_href="/admin/blogs/618449">http://ari.iteye.com/admin/blogs/618449

一、Spring JDBC 概述

Spring 提供了一个强有力的模板类JdbcTemplate��化JDBC操作�Q�DataSource,JdbcTemplate都可以以Bean的方式定义在想xml配置文�g�Q�JdbcTemplate创徏只需注入一个DataSource�Q�应用程序Dao层只需要��承JdbcDaoSupport, 或者注入JdbcTemplate�Q�便可以获取JdbcTemplate�Q�JdbcTemplate是一个线�E�安全的�c�，多个Dao可以注入一个JdbcTemplate�Q?/p>

然后��jdbcTemplate对象注入自定义的Dao、或者��承JdbcDaoSupport�Q�例如：

public class JdbcCustomerDao extends JdbcDaoSupport implements CustomerDao {
}
public class JdbcCustomerDao implements CustomerDao {
private JdbcTemplate jdbcTemplate
public void setJdbcTemplate()JdbcTemplate jdbcTemplate{
this.jdbcTemplate=jdbcTemplate
}
}

二�?nbsp;JdbcTemplate 提供以下主要�Ҏ��化JDBC操作�Q?/strong>

2.1、List query(String sql,Ojbect[] args,RowMapper rowMapper)

     说明�Q�常用的查询�Q�sql待执行的sql语句�Q�args是sql语句的参敎ͼ�rowMapper负责��每一行记录�{化�ؓjava对象存放在list�Q��ƈ最�l�返回，例如�Q?/p>
public List queryByAuthor(String author) { String sql = "select * from book where author=?"; Collection c = getJdoTemplate().find(sql, new Object[] { author },new BookRowMapper()); List books = new ArrayList(); books.addAll(c); return books; } class BookRowMapper implements RowMapper{ public Object mapRow(ResultSet res, int index) throws SQLException { Book book = new Book(); book.setId(rs.getInt("id")); //省略set return book�Q? } }

   更新、删除、其他查询操作类��|��举例如下�Q�详�l�细节请参考spring api�Q?/p>

//�q�回��gؓ一个长整�Ş public long getAverageAge() { return getJdbcTemplate().queryForLong("SELECT AVG(age) FROM employee"); } //�q�回一个整�? public int getTotalNumberOfEmployees() { return getJdbcTemplate().queryForInt("SELECT COUNT(0) FROM employees"); } //更新操作 this.jdbcTemplate.update( "insert into t_actor (first_name, surname) values (?, ?)", new Object[] {"Leonor", "Watling"});

2.2、spring 2.5新功能，另类的jdbc ORM�Q�BeanPropertyRowMapper

      上面我们��索时必须实现RowMapper�Q�将�l�果集�{化�ؓjava对象。Spring2.5 ��化了�q�一操作�Q��得我们不必再实现RowMapper�Q�实现此功能的俩个神奇东东便是：ParameterizedRowMapper�Q�ParameterizedBeanPropertyRowMapper�Q�貌似通过java反射机制实现了将resultset字段映射到java对象�Q�但是数据表的列必须和java对象的属性对应，没有研究源码�Q�有点类��g��apache 的BeanUtil�Q�不知�ؓ何这部分在spring开发参考手册没有，��N��不是�l�典�?/p>

//使用ParameterizedBeanPropertyRowMapper @SuppressWarnings({"unchecked"}) public List getAll() { return getJdbcTemplate().query("select * from t_customer", ParameterizedBeanPropertyRowMapper.newInstance(Customer.class)); } //使用BeanPropertyRowMapper @SuppressWarnings({"unchecked"}) public List getAll() { return getJdbcTemplate().query("select * from t_customer", new BeanPropertyRowMapper(Customer.class)); }

注意�Q�ParameterizedBeanPropertyRowMapper是BeanPropertyRowMapper子类。另外表的字�D�名�U�必��d��实体�cȝ��成员变量名称一��_��

2.3、spring之JDBC扚w��操作

      jdbcTemplate.batchUpdate(final String[] sql) �Q�API解释�Q�Issue multiple SQL updates on a single JDBC Statement using batching�Q�翻译过来大致�ؓ�Q�解军_��个sql的插入、更新、删除操作在一个Statement中。性能一般�?/span>

   jdbcTemplate.batchUpdate(String sql, final BatchPreparedStatementSetter pss),�c�M��于JDBC的PreparedStatement�Q�性能较上着有所提高�?/span>

   我们举例说明如何使用�Q�示例如�?

final int count = 2000; final List firstNames = new ArrayList(count); final List lastNames = new ArrayList(count); for (int i = 0; i < count; i++) { firstNames.add("First Name " + i); lastNames.add("Last Name " + i); } jdbcTemplate.batchUpdate( "insert into customer (id, first_name, last_name, last_login, comments) values (?, ?, ?, ?, ?)", new BatchPreparedStatementSetter() { //为prepared statement讄��参数。这个方法将在整个过�E�中被调用的�ơ数 public void setValues(PreparedStatement ps, int i) throws SQLException { ps.setLong(1, i + 10); ps.setString(2, firstNames.get(i)); ps.setString(3, lastNames.get(i)); ps.setNull(4, Types.TIMESTAMP); ps.setNull(5, Types.CLOB); } //�q�回更新的结果集条数 public int getBatchSize() { return count; } }); }

BatchSqlUpdate�c�L��SqlUpdate 的子�c�，适用于插入、删除、更新批量操作，内部使用PreparedStatement�Q�所以效率很高，扚w��语句辑ֈ�讑֮�的batchSize�Q�或者手动调用flush才会执行扚w��操作。注意：此类是非�U�程安全的，必须为每个��用者创��Z��个实例，或者在同一个线�E�中使用前调用reset�?/span>

   下面我们举例说明如何使用BatchSqlUpdate�Q�来执行扚w��操作。示例如下：

class BatchInsert extends BatchSqlUpdate { private static final String SQL = "insert into t_customer (id, first_name, last_name, last_login, " + "comments) values (?, ?, ?, ?, null)"; BatchInsert(DataSource dataSource) { super(dataSource, SQL); declareParameter(new SqlParameter(Types.INTEGER)); declareParameter(new SqlParameter(Types.VARCHAR)); declareParameter(new SqlParameter(Types.VARCHAR)); declareParameter(new SqlParameter(Types.TIMESTAMP)); setBatchSize(10); } }

int count = 5000; for (int i = 0; i < count; i++) { batchInsert.update(new Object[] { i + 100L, "a" + i, "b" + i, null }); }

��x��Q�spring JDBC主要的应用基本上都简单罗列一番，所有代码均为文章�D例，不是很严谨，仅�ؓ演示每一�U�用法，抛砖引玉�Q�希望有独特见解的拍砖，有问题的��h��明问题所�?谢谢

�I�白 2011-05-10 21:06 发表评论

Tomcat6.x目录与server.xml详解

�I�白 — Tue, 10 May 2011 13:04:00 GMT
     摘要: 本文参考自�Q�Tomcat全攻�?参考链接：http://www.ibm.com/developerworks/cn/java/l-tomcat/index.html#1      Tomcat 服务器是一个免费的开放源代码的Web 应用服务器，目前最新版本是6.x�Q�相�?.x性能提升很多�Q�主�?..  阅读全文

�I�白 2011-05-10 21:04 发表评论

�I�白 — Tue, 10 May 2011 13:03:00 GMT

��目中有个业务处理类大小117K�Q�代�?700行，看此�c�d��炚w��L��Q�如今如要增加业务逻辑大约20个吧�Q�此�c�d��果随着��目工程的二期、三期如�ơ添加逻辑�q�早有一天大��达到M�Q�噢、mygod。细心研��d��人的工作�ȝ��Q�发现其中有点可攚w��的蛛丝马迹(本�h很笨、别�W�我才发现如何改�?�?/p>
     下面我们对业务流�E�、以及涉及的相关�c�进行介�l�，Msg代表接受到客��L��的一个消息报文，消息报文�l�构�Q�消息头+消息体，消息头参数固定、消息体参数不定�Q�下面是一个简单的�c�d��Q�这只是一个模拟场景，****Req代表各户端请求类�Q?span lang="EN-US">***Rsp代表�q�回�l�客��L��的参数类。实际比此复杂，为描�q�问题我们简单摘除几个类介绍�Q�别问我��Z��q�么设计�l�承。类�?span lang="EN-US">msg�?span lang="EN-US">msgHead是组合关�p�M��许画错了、不当之处请指出�Q�勿恶语向伤�Q?/span>

处理��h��Handler�cȝ��代码逻辑如下�Q?/p>

//�c�M��主要�Ҏ��如下 public void execute(Object object) { Message message = (Message)object; int opcode = message.getOpcode(); int connectId = message.getConnectId(); //消息头已�l�解析，获取消息体，卛_��c�d��性字节数�l? byte[] bytes = message.getBytes(); if (opcode == MsgInfo.ADD_RING) { // 订购彩铃 orderRing(connectId, bytes); } else if (opcode == MsgInfo.PRESENT_RING) { // 赠送彩�? presentRing(connectId, bytes); } else if (opcode == MsgInfo.DEL_RING) { // 删除个�h铃音 delPersonalRing(connectId, bytes); } //此处省略n个else if } //其他删除、赠送与省略的else if中的处理逻辑与之基本相同 private void orderRing(int connectId, byte[] bytes) { //处理�Ҏ��分�ؓ四步�Q�具体代码省�? //1、解析字节数�l��ؓ订购铃音�c? //2、处理订购关�p? //3、处理结果封装�ؓ订购响应�c? //4、发送回客户�? } //省略presentRing、delPersonalRing�{�一�p�d��其他�Ҏ��Q�所有的处理�Ҏ��参数相同……

    鉴于此、想��C��用命令模式改造此�c�，如果不了解命令模式请阅读相关书籍�Q�大话设计模式或设计与模式，�q�里我们仅给出大致的定于与类图�?/p>
何谓命��o模式�Q�将一个请求封装�ؓ一个对象，从而是你可用不同的��h��对客��L��参数化，对请求排队或记录日志�Q�以及支持可撤销的操作�?/p>
Shit、这句话很难理解哦，那就先别理解了，我们看下命��o模式的类图，然后介绍如何使用命��o模式攚w��上面的elseif�?/p>
�c�d��先省略，上班��L��写的�Q?/p>

下面�q�入正题�Q�对Handler��手术开始，主要考虑如下�Q?/p>
1�?/span>提炼�Ҏ��

     ��每�?span lang="EN-US">if语句块中的逻辑提取��Z��个方法，�q�里我们�?span lang="EN-US">handler已经实现�Q�就是：orderRing�?span mce_style="font-family: 'Courier New'; color: black; font-size: 10pt;" style="font-family: 'Courier New'; color: black; font-size: 10pt; ">presentRing�?span mce_style="font-family: 'Courier New'; color: black; font-size: 10pt;" style="font-family: 'Courier New'; color: black; font-size: 10pt; ">delPersonalRing�?#8230;…�?/p>
2�?/span>提炼�c?/strong>

��每个业务处理方法提取�ؓ以各�c�，然后对具体类�q�行抽象�Q�提取父�c�L��者接口；代码如下�Q?/p>

public Abstract class Command{ public void execute() �? public class OrderRingCommand extends Command { private Handler hander; public OrderRingCommand(Handler hander){ this.hander = hander; } public void execute(int connectId, byte[] bytes){ //1、解析字节数�l��ؓ订购铃音�c? //2、增加订购关�p? //3、处理结果封装�ؓ订购响应�c? //4、发送回客户�? } /** * 1、解析字节数�l��ؓ订购铃音�c? */ public void method1(){ } /** * 2、处理订购关�p? */ public void method2(){ } /** * 3、处理结果封装�ؓ订购响应�c? */ public void method3(){ } /** * 4、结果发送回客户�? */ public void method4(){ } } public class DelRingCommand extends Command { private Handler hander; public DelRingCommand(Handler hander){ this.hander = hander; } public void execute(int connectId, byte[] bytes){ //1、解析字节数�l��ؓ订购铃音�c? //2、删除购关系 //3、处理结果封装�ؓ订购响应�c? //4、发送回客户�? } //提取�Ҏ�� }



3�?/span>命��o模式攚w��替�?/strong>elseif�Q?/strong>

Map map = new HashMap(); static{ map.put(MsgInfo.ADD_RING, new OrderRingCommand()); //省却其他�Q�这里仅为演�C�，实际��目中实例化�c�通过spring容器或者其他方�? } public void execute(Object object) { Message message = (Message)object; int opcode = message.getOpcode(); int connectId = message.getConnectId(); //消息头已�l�解析，获取消息体，卛_��c�d��性字节数�l? byte[] bytes = message.getBytes(); map.get(opcode).execute(connectId,bytes); }



命��o模式替换else if代码坏味道的重构�l�束�Q�众多的if条�g块烟消云散，取而代之的是一个个�_��的类�Q�doc版本在附件中

�I�白 2011-05-10 21:03 发表评论

深入��出ThreadLocal

�I�白 — Tue, 10 May 2011 13:02:00 GMT

一、ThreadLocal概述

       学习JDK中的�c�，首先看下JDK API�Ҏ��cȝ��描述�Q�描�q�如下：

JDK API 写道

该类提供了线�E�局�?(thread-local) 变量。这些变量不同于它们的普通对应物�Q�因��问某个变量（通过�?get �?set �Ҏ��Q�的每个�U�程都有自己的局部变量，它独立于变量的初始化副本。ThreadLocal 实例通常是类中的 private static 字段�Q�它们希望将状态与某一个线�E�（例如�Q�用�?ID 或事�?ID�Q�相兌��?nbsp;

    API表达了下面几�U�观点：

1、ThreadLocal不是�U�程�Q�是�U�程的一个变量，你可以先��单理解�ؓ�U�程�cȝ��属性变量�?/p>
2、ThreadLocal 在类中通常定义为静态类变量�?/p>
3、每个线�E�有自己的一个ThreadLocal�Q�它是变量的一�?#8216;拯��’�Q�修改它不媄响其他线�E��?/p>

    既然定义为类变量�Q��ؓ何�ؓ每个�U�程�l�护一个副本（姑且成�ؓ‘拯��’�Ҏ��理解�Q�，让每个线�E�独立访问？多线�E�编�E�的�l�验告诉我们�Q�对于线�E�共享资源（你可以理解�ؓ属性）�Q�资源是否被所有线�E�共享，也就是说�q�个资源被一个线�E�修�Ҏ��否媄响另一个线�E�的�q�行�Q�如果媄响我们需要��用synchronized同步�Q�让�U�程��序讉K��?/p>

   ThreadLocal适用于资源共享但不需要维护状态的情况�Q�也��是一个线�E�对资源的修改，不媄响另一个线�E�的�q�行�Q�这�U�设计是‘�I�间换时�?#8217;�Q�synchronized��序执行�?strong>‘旉��换取�I�间’�?/p>

二、ThreadLocal�Ҏ��介绍

T get()
          �q�回此线�E�局部变量的当前�U�程副本中的倹{�?/td>

protected T initialValue()
          �q�回此线�E�局部变量的当前�U�程�?#8220;初始�?#8221;�?/td>

void remove()
          �U�除此线�E�局部变量当前线�E�的倹{�?/td>

void set(T value)
          ��此�U�程局部变量的当前�U�程副本中的��D��|��ؓ指定倹{�?/td>

三、深入源�?/strong>

    ThreadLocal有一个ThreadLocalMap静态内部类�Q�你可以��单理解�ؓ一个MAP�Q�这�?#8216;Map’为每个线�E�复制一个变量的‘拯��’存储其中�?/p>
    当线�E�调用ThreadLocal.get()�Ҏ��获取变量�?首先获取当前�U�程引用�Q�以此�ؓkey去获取响应的ThreadLocalMap�Q�如果此‘Map’不存在则初始化一个，否则�q�回其中的变量，代码如下�Q?/p>

public T get() { Thread t = Thread.currentThread(); ThreadLocalMap map = getMap(t); if (map != null) { ThreadLocalMap.Entry e = map.getEntry(this); if (e != null) return (T)e.value; } return setInitialValue(); }

    调用get�Ҏ��如果此Map不存在首先初始化�Q�创建此map�Q�将�U�程为key�Q�初始化的vlaue存入其中�Q�注意此处的initialValue�Q�我们可以覆盖此�Ҏ��Q�在首次调用时初始化一个适当的倹{��setInitialValue代码如下�Q?/p>
private T setInitialValue() { T value = initialValue(); Thread t = Thread.currentThread(); ThreadLocalMap map = getMap(t); if (map != null) map.set(this, value); else createMap(t, value); return value; }

    set�Ҏ��相对比较��单如果理解以上俩个方法，获取当前�U�程的引用，从map中获取该�U�程对应的map�Q�如果map存在更新�~�存��|��否则创徏�q�存储，代码如下�Q?/p>
public void set(T value) { Thread t = Thread.currentThread(); ThreadLocalMap map = getMap(t); if (map != null) map.set(this, value); else createMap(t, value); }

    对于ThreadLocal在何处存储变量副本，我们看getMap�Ҏ��Q�获取的是当前线�E�的ThreadLocal�c�d��的threadLocals属性。显然变量副本存储在每一个线�E�中�?/p>

/** * 获取�U�程的ThreadLocalMap 属性实�? */ ThreadLocalMap getMap(Thread t) { return t.threadLocals; }

    上面我们知道变量副本存放于何处，�q�里我们��单说下如何被java的垃圾收集机制收集，当我们不在��用是调用set(null)�Q�此时不在将引用指向�?#8216;map’�Q�而线�E�退出时会执行资源回收操作，��申��L��资源�q�行回收�Q�其实就是将属性的引用讄��为null。这时已�l�不在有��M��引用指向该map�Q�故而会被垃圾收集�?/p>

四、ThreadLocal应用�C�Z��

      在我的另一��文章，对ThreadLocal的��用做了一个实例，此示例也可以用作生��环境�Q�请参见�Q?a mce_href="/blog/757641">http://ari.iteye.com/blog/757641

如有问题��L��a�讨论�Q�谢�?/p>

�I�白 2011-05-10 21:02 发表评论

ThreadLocal�C�Z��

�I�白 — Tue, 10 May 2011 13:01:00 GMT

本文借花献佛�Q�引用Tim Cull的博�?#8220;SimpleDateFormat: Performance Pig”介绍下ThreadLocal的简单��用，同时也对SimpleDateFormat的��用有个深入的了解�?/p>
Tim Cull 写道

Just yesterday I came across this problem “in the wild” for the third time in my career so far: an application with performance problems creating tons of java.text.SimpleDateFormat instances. So, I have to get this out there: creating a new instance of SimpleDateFormat is incredibly expensive and should be minimized. In the case that prompted this post, I was using JProfiler to profile this code that parses a CSV file and discovered that 50% of the time it took to suck in the file and make 55,000 objects out of it was spent solely in the constructor of SimpleDateFormat. It created and then threw away a new one every time it had to parse a date. Whew!

“Great,” you think, “I’ll just create one, static instance, slap it in a field in a DateUtils helper class and life will be good.”

Well, more precisely, life will be good about 97% of the time. A few days after you roll that code into production you’ll discover the second cool fact that’s good to know: SimpleDateFormat is not thread safe. Your code will work just fine most of the time and all of your regression tests will probably pass, but once your system gets under a production load you’ll see the occasional exception.

“Fine,” you think, “I’ll just slap a ’synchronized’ around my use of that one, static instance.”

Ok, fine, you could do that and you’d be more or less ok, but the problem is that you’ve now taken a very common operation (date formatting and parsing) and crammed all of your otherwise-lovely, super-parallel application through a single pipe to get it done.

     大致意思：Tim Cull��到一个SimpleDateFormat带来的严重的性能问题�Q�该问题主要有SimpleDateFormat引发�Q�创��Z��个SimpleDateFormat实例的开销比较昂贵�Q�解析字�W�串旉��旉��J�创建生命周期短暂的实例��D��性能低下。即使将SimpleDateFormat定义为静态类变量�Q�貌��D��解决�q�个问题�Q�但是SimpleDateFormat是非�U�程安全的，同样存在问题�Q�如果用‘synchronized’�U�程同步同样面��问题�Q�同步导致性能下降�Q�线�E�之间序列化的获取SimpleDateFormat实例�Q��?/p>
    Tim Cull使用Threadlocal解决了此问题�Q�对于每个线�E�SimpleDateFormat不存在媄响他们之间协作的状态，为每个线�E�创��Z��个SimpleDateFormat变量的拷贝或者叫做副本，代码如下�Q?/p>

import java.text.DateFormat; import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.Date; /** * 使用ThreadLocal以空间换旉��解决SimpleDateFormat�U�程安全问题�? * @author * */ public class DateUtil { private static final String DATE_FORMAT = "yyyy-MM-dd HH:mm:ss"; @SuppressWarnings("rawtypes") private static ThreadLocal threadLocal = new ThreadLocal() { protected synchronized Object initialValue() { return new SimpleDateFormat(DATE_FORMAT); } }; public static DateFormat getDateFormat() { return (DateFormat) threadLocal.get(); } public static Date parse(String textDate) throws ParseException { return getDateFormat().parse(textDate); } }

   创徏一个ThreadLocal�c�d��量，�q�里创徏时用了一个匿名类�Q�覆盖了initialValue�Ҏ��Q�主要作用是创徏时初始化实例。也可以采用下面方式创徏�Q?/p>

//�W�一�ơ调用get��返回null private static ThreadLocal threadLocal = new ThreadLocal()�Q? //获取�U�程的变量副本，如果不覆盖initialValue�Q�第一�ơget�q�回null�Q�故需要初始化一个SimpleDateFormat�Q��ƈset到threadLocal�? public static DateFormat getDateFormat() { DateFormat df = (DateFormat) threadLocal.get(); if(df==null){ df = new SimpleDateFormat(DATE_FORMAT) threadLocal.set(df); } return df; }

   我们看下我们覆盖的initialValue�Ҏ��Q?/p>

protected T initialValue() { return null;//直接�q�回null }

�I�白 2011-05-10 21:01 发表评论

探究Struts2�q�行机制�Q�StrutsPrepareAndExecuteFilter 源码剖析

�I�白 — Tue, 10 May 2011 12:58:00 GMT

作者：niumd

  blog�Q?a mce_href="/">http://ari.iteye.com

一、概�q?/strong>

     Struts2的核心是一个Filter�Q�Action可以��q��web容器�Q�那么是什么让http��h��和action兌��在一��L��Q�下面我们深入源码来分析下Struts2是如何工作的�?/p>
FilterDispatcher API 写道

Deprecated. Since Struts 2.1.3, use StrutsPrepareAndExecuteFilter instead or StrutsPrepareFilter and StrutsExecuteFilter if needing using the ActionContextCleanUp filter in addition to this one

     鉴于常规情况官方推荐使用StrutsPrepareAndExecuteFilter替代FilterDispatcher�Q�我们此文将剖析StrutsPrepareAndExecuteFilter�Q�其在工�E�中作�ؓ一个Filter配置在web.xml中，配置如下�Q?/p>
struts2 org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter struts2 /*

二、源码属性方法简�?/strong>

    下面我们研究下StrutsPrepareAndExecuteFilter源码�Q�类的主要信息如下：

属性摘�?/strong>

protected List<Pattern> excludedPatterns


protected ExecuteOperations execute


protected PrepareOperations prepare


    StrutsPrepareAndExecuteFilter与普通的Filter�q�无区别�Q�方法除�l�承自Filter外，仅有一个回调方法，�W�三部分我们��按照Filter�Ҏ��调用��序�Q�由init�?gt;doFilter�?gt;destroy��序地分析源码�?/p>

�Ҏ��摘要

void destroy()
           �l�承自Filter�Q�用于资源释�?/td>

void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
           �l�承自Filter�Q�执行方�?/td>

void init(FilterConfig filterConfig)
           �l�承自Filter�Q�初始化参数

protected void postInit(Dispatcher dispatcher, FilterConfig filterConfig)
          Callback for post initialization�Q�一个空的方法，用于�Ҏ��回调初始化）

三、源码剖�?nbsp;

    1、init�Ҏ��

         init是Filter�W�一个运行的�Ҏ��Q�我们看下struts2的核心Filter在调用init�Ҏ��初始化时做哪些工作：

public void init(FilterConfig filterConfig) throws ServletException { InitOperations init = new InitOperations(); try { //��装filterConfig�Q�其中有个主要方法getInitParameterNames��参数名字以String格式存储在List�? FilterHostConfig config = new FilterHostConfig(filterConfig); // 初始化struts内部日志 init.initLogging(config); //创徏dispatcher �Q��ƈ初始化，�q�部分下面我们重点分析，初始化时加蝲那些资源 Dispatcher dispatcher = init.initDispatcher(config); init.initStaticContentLoader(config, dispatcher); //初始化类属性：prepare 、execute prepare = new PrepareOperations(filterConfig.getServletContext(), dispatcher); execute = new ExecuteOperations(filterConfig.getServletContext(), dispatcher); this.excludedPatterns = init.buildExcludedPatternsList(dispatcher); //回调�I�的postInit�Ҏ�� postInit(dispatcher, filterConfig); } finally { init.cleanup(); } }

   首先看下FilterHostConfig �Q�源码如下：

public class FilterHostConfig implements HostConfig { private FilterConfig config; /** *构造函�? */ public FilterHostConfig(FilterConfig config) { this.config = config; } /** * �Ҏ��init-param配置的param-name获取param-value的�? */ public String getInitParameter(String key) { return config.getInitParameter(key); } /** * �q�回初始化参数名的List */ public Iterator getInitParameterNames() { return MakeIterator.convert(config.getInitParameterNames()); } public ServletContext getServletContext() { return config.getServletContext(); } }

   只有短短的几行代码，getInitParameterNames是这个类的核心，��Filter初始化参数名�U�有枚�D�c�d��转�ؓIterator。此�cȝ��主要作�ؓ是对filterConfig ��装�?/p>

    重点来了�Q�创建�ƈ初始化Dispatcher

public Dispatcher initDispatcher( HostConfig filterConfig ) { Dispatcher dispatcher = createDispatcher(filterConfig); dispatcher.init(); return dispatcher; }

     创徏Dispatcher�Q�会��d�� filterConfig 中的配置信息�Q�将配置信息解析出来�Q�封装成��Z��个Map�Q�然后根�l�servlet上下文和参数Map构造Dispatcher �Q?/p>
private Dispatcher createDispatcher( HostConfig filterConfig ) { Map params = new HashMap(); for ( Iterator e = filterConfig.getInitParameterNames(); e.hasNext(); ) { String name = (String) e.next(); String value = filterConfig.getInitParameter(name); params.put(name, value); } return new Dispatcher(filterConfig.getServletContext(), params); }

Dispatcher初始化，加蝲struts2的相关配�|�文�Ӟ��按照顺序逐一加蝲�Q�default.properties�Q�struts-default.xml,struts-plugin.xml,struts.xml�Q?#8230;…

/** *初始化过�E�中依次加蝲如下配置文�g */ public void init() { if (configurationManager == null) { configurationManager = new ConfigurationManager(BeanSelectionProvider.DEFAULT_BEAN_NAME); } try { //加蝲org/apache/struts2/default.properties init_DefaultProperties(); // [1] //加蝲struts-default.xml,struts-plugin.xml,struts.xml init_TraditionalXmlConfigurations(); // [2] init_LegacyStrutsProperties(); // [3] //用户自己实现的ConfigurationProviders�c? init_CustomConfigurationProviders(); // [5] //Filter的初始化参数 init_FilterInitParameters() ; // [6] init_AliasStandardObjects() ; // [7] Container container = init_PreloadConfiguration(); container.inject(this); init_CheckConfigurationReloading(container); init_CheckWebLogicWorkaround(container); if (!dispatcherListeners.isEmpty()) { for (DispatcherListener l : dispatcherListeners) { l.dispatcherInitialized(this); } } } catch (Exception ex) { if (LOG.isErrorEnabled()) LOG.error("Dispatcher initialization failed", ex); throw new StrutsException(ex); } }

   初始化default.properties�Q�具体的初始化操作在DefaultPropertiesProvider�c�M��



private void init_DefaultProperties() { configurationManager.addConfigurationProvider(new DefaultPropertiesProvider()); }



   下面我们看下DefaultPropertiesProvider�c�L��码：

public void register(ContainerBuilder builder, LocatableProperties props) throws ConfigurationException { Settings defaultSettings = null; try { defaultSettings = new PropertiesSettings("org/apache/struts2/default"); } catch (Exception e) { throw new ConfigurationException("Could not find or error in org/apache/struts2/default.properties", e); } loadSettings(props, defaultSettings); }

   其他的我们再�ơ省略，大家可以��览下各个初始化操作都加载了那些文�g

3、doFilter�Ҏ��

     doFilter是过滤器的执行方法，它拦截提交的HttpServletRequest��h��Q�HttpServletResponse响应�Q�作为strtus2的核心拦截器�Q�在doFilter里面到底做了哪些工作�Q�我们将逐行解读其源码，源码如下�Q?/p>

public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException { //父类向子�c��{�Q�强转�ؓhttp��h��、响�? HttpServletRequest request = (HttpServletRequest) req; HttpServletResponse response = (HttpServletResponse) res; try { //讄��~�码和国际化 prepare.setEncodingAndLocale(request, response); //创徏Action上下文（重点�Q? prepare.createActionContext(request, response); prepare.assignDispatcherToThread(); if ( excludedPatterns != null && prepare.isUrlExcluded(request, excludedPatterns)) { chain.doFilter(request, response); } else { request = prepare.wrapRequest(request); ActionMapping mapping = prepare.findActionMapping(request, response, true); if (mapping == null) { boolean handled = execute.executeStaticResourceRequest(request, response); if (!handled) { chain.doFilter(request, response); } } else { execute.executeAction(request, response, mapping); } } } finally { prepare.cleanupRequest(request); } }

    setEncodingAndLocale调用了dispatcher�Ҏ��的prepare�Ҏ��Q?/p>

/** * Sets the request encoding and locale on the response */ public void setEncodingAndLocale(HttpServletRequest request, HttpServletResponse response) { dispatcher.prepare(request, response); }

   下面我们看下prepare�Ҏ��Q�这个方法很��单只是设�|�了encoding 、locale �Q�做的只是一些辅助的工作�Q?/p>
public void prepare(HttpServletRequest request, HttpServletResponse response) { String encoding = null; if (defaultEncoding != null) { encoding = defaultEncoding; } Locale locale = null; if (defaultLocale != null) { locale = LocalizedTextUtil.localeFromString(defaultLocale, request.getLocale()); } if (encoding != null) { try { request.setCharacterEncoding(encoding); } catch (Exception e) { LOG.error("Error setting character encoding to '" + encoding + "' - ignoring.", e); } } if (locale != null) { response.setLocale(locale); } if (paramsWorkaroundEnabled) { request.getParameter("foo"); // simply read any parameter (existing or not) to "prime" the request } }

   Action上下文创建（重点�Q?/strong>

       ActionContext是一个容器，�q�个�Ҏ��主要存储request、session、application、parameters�{�相关信�?ActionContext是一个线�E�的本地变量�Q�这意味着不同的action之间不会�׃�nActionContext�Q�所以也不用考虑�U�程安全问题。其实质是一个Map�Q�key是标�C�request、session�?#8230;…的字�W�串�Q�值是其对应的对象�Q?/p>
static ThreadLocal actionContext = new ThreadLocal(); Map context;

   下面我们看下如何创徏action上下文的�Q�代码如下：

/** *创徏Action上下文，初始化thread local */ public ActionContext createActionContext(HttpServletRequest request, HttpServletResponse response) { ActionContext ctx; Integer counter = 1; Integer oldCounter = (Integer) request.getAttribute(CLEANUP_RECURSION_COUNTER); if (oldCounter != null) { counter = oldCounter + 1; } //注意此处是从ThreadLocal中获取此ActionContext变量 ActionContext oldContext = ActionContext.getContext(); if (oldContext != null) { // detected existing context, so we are probably in a forward ctx = new ActionContext(new HashMap(oldContext.getContextMap())); } else { ValueStack stack = dispatcher.getContainer().getInstance(ValueStackFactory.class).createValueStack(); stack.getContext().putAll(dispatcher.createContextMap(request, response, null, servletContext)); //stack.getContext()�q�回的是一个Map�Q�根据此Map构造一个ActionContext ctx = new ActionContext(stack.getContext()); } request.setAttribute(CLEANUP_RECURSION_COUNTER, counter); //��ActionContext存如ThreadLocal ActionContext.setContext(ctx); return ctx; }

    上面代码中dispatcher.createContextMap�Q�如何封装相兛_��敎ͼ�

public Map createContextMap(HttpServletRequest request, HttpServletResponse response, ActionMapping mapping, ServletContext context) { // request map wrapping the http request objects Map requestMap = new RequestMap(request); // parameters map wrapping the http parameters. ActionMapping parameters are now handled and applied separately Map params = new HashMap(request.getParameterMap()); // session map wrapping the http session Map session = new SessionMap(request); // application map wrapping the ServletContext Map application = new ApplicationMap(context); //requestMap、params、session�{�Map��装成�ؓ一个上下文Map�Q�逐个调用了map.put(Map p). Map extraContext = createContextMap(requestMap, params, session, application, request, response, context); if (mapping != null) { extraContext.put(ServletActionContext.ACTION_MAPPING, mapping); } return extraContext; }

我们��单看下RequestMap�Q�其他的省略。RequestMap�c�d��C��抽象Map�Q�故其本�w�是一个Map�Q�主要方法实玎ͼ�

//map的get实现 public Object get(Object key) { return request.getAttribute(key.toString()); } //map的put实现 public Object put(Object key, Object value) { Object oldValue = get(key); entries = null; request.setAttribute(key.toString(), value); return oldValue; }

   下面是源码展�C�Z��如何执行Action控制器：

public void executeAction(HttpServletRequest request, HttpServletResponse response, ActionMapping mapping) throws ServletException { dispatcher.serviceAction(request, response, servletContext, mapping); } public void serviceAction(HttpServletRequest request, HttpServletResponse response, ServletContext context, ActionMapping mapping) throws ServletException { //��装执行的上下文环境�Q�主要讲相关信息存储入map Map extraContext = createContextMap(request, response, mapping, context); // If there was a previous value stack, then create a new copy and pass it in to be used by the new Action ValueStack stack = (ValueStack) request.getAttribute(ServletActionContext.STRUTS_VALUESTACK_KEY); boolean nullStack = stack == null; if (nullStack) { ActionContext ctx = ActionContext.getContext(); if (ctx != null) { stack = ctx.getValueStack(); } } if (stack != null) { extraContext.put(ActionContext.VALUE_STACK, valueStackFactory.createValueStack(stack)); } String timerKey = "Handling request from Dispatcher"; try { UtilTimerStack.push(timerKey); //获取命名�I�间 String namespace = mapping.getNamespace(); //获取action配置的name属�? String name = mapping.getName(); //获取action配置的method属�? String method = mapping.getMethod(); Configuration config = configurationManager.getConfiguration(); //�Ҏ��执行上下文参敎ͼ�命名�I�间�Q�名�U�等创徏用户自定义Action的代理对�? ActionProxy proxy = config.getContainer().getInstance(ActionProxyFactory.class).createActionProxy( namespace, name, method, extraContext, true, false); request.setAttribute(ServletActionContext.STRUTS_VALUESTACK_KEY, proxy.getInvocation().getStack()); // if the ActionMapping says to go straight to a result, do it! //执行execute�Ҏ��Q��ƈ转向�l�果 if (mapping.getResult() != null) { Result result = mapping.getResult(); result.execute(proxy.getInvocation()); } else { proxy.execute(); } // If there was a previous value stack then set it back onto the request if (!nullStack) { request.setAttribute(ServletActionContext.STRUTS_VALUESTACK_KEY, stack); } } catch (ConfigurationException e) { // WW-2874 Only log error if in devMode if(devMode) { String reqStr = request.getRequestURI(); if (request.getQueryString() != null) { reqStr = reqStr + "?" + request.getQueryString(); } LOG.error("Could not find action or result\n" + reqStr, e); } else { LOG.warn("Could not find action or result", e); } sendError(request, response, context, HttpServletResponse.SC_NOT_FOUND, e); } catch (Exception e) { sendError(request, response, context, HttpServletResponse.SC_INTERNAL_SERVER_ERROR, e); } finally { UtilTimerStack.pop(timerKey); } }

   文中对如何解析Struts.xml�Q�如何将URL与action映射匚w��为分析，有需要的我后�l�补全，因�ؓStrutsXmlConfigurationProvider�l�承XmlConfigurationProvider�Q��ƈ在register�Ҏ��回调父类的register�Q�有兴趣的可以深入阅��M��下XmlConfigurationProvider源码�Q?/p>

public void register(ContainerBuilder containerBuilder, LocatableProperties props) throws ConfigurationException { if (servletContext != null && !containerBuilder.contains(ServletContext.class)) { containerBuilder.factory(ServletContext.class, new Factory() { public ServletContext create(Context context) throws Exception { return servletContext; } }); } //调用父类的register�Q�关键点所�? super.register(containerBuilder, props); }

     struts2-core-2.2.1.jar包中struts-2.1.7.dtd对于Action的定义如下：

    从上�q�DTD中可见Action元素可以含有name 、class 、method 、converter 属性�?/p>

   XmlConfigurationProvider解析struts.xml配置的Action元素�Q?/p>
protected void addAction(Element actionElement, PackageConfig.Builder packageContext) throws ConfigurationException { String name = actionElement.getAttribute("name"); String className = actionElement.getAttribute("class"); String methodName = actionElement.getAttribute("method"); Location location = DomHelper.getLocationObject(actionElement); if (location == null) { LOG.warn("location null for " + className); } //methodName should be null if it's not set methodName = (methodName.trim().length() > 0) ? methodName.trim() : null; // if there isnt a class name specified for an then try to // use the default-class-ref from the if (StringUtils.isEmpty(className)) { // if there is a package default-class-ref use that, otherwise use action support /* if (StringUtils.isNotEmpty(packageContext.getDefaultClassRef())) { className = packageContext.getDefaultClassRef(); } else { className = ActionSupport.class.getName(); }*/ } else { if (!verifyAction(className, name, location)) { if (LOG.isErrorEnabled()) LOG.error("Unable to verify action [#0] with class [#1], from [#2]", name, className, location.toString()); return; } } Map results; try { results = buildResults(actionElement, packageContext); } catch (ConfigurationException e) { throw new ConfigurationException("Error building results for action " + name + " in namespace " + packageContext.getNamespace(), e, actionElement); } List interceptorList = buildInterceptorList(actionElement, packageContext); List exceptionMappings = buildExceptionMappings(actionElement, packageContext); ActionConfig actionConfig = new ActionConfig.Builder(packageContext.getName(), name, className) .methodName(methodName) .addResultConfigs(results) .addInterceptors(interceptorList) .addExceptionMappings(exceptionMappings) .addParams(XmlHelper.getParams(actionElement)) .location(location) .build(); packageContext.addActionConfig(name, actionConfig); if (LOG.isDebugEnabled()) { LOG.debug("Loaded " + (StringUtils.isNotEmpty(packageContext.getNamespace()) ? (packageContext.getNamespace() + "/") : "") + name + " in '" + packageContext.getName() + "' package:" + actionConfig); } }

     工作中不涉及Struts2�Q�本周工作有�?天的�I�档期，�E�微看了下struts2的文档，写了个demo�Q�从源码的角度研�I�了下运行原理，如有分析不当��h��出，我后�l�逐步完善更正�Q�大家共同提高�?/p>

�I�白 2011-05-10 20:58 发表评论

NetBean6字体配置

�I�白 — Sun, 07 Sep 2008 05:46:00 GMT
     摘要: 解决netbean、squirrel-sql-2.4.1�{�java开发��Y�?英文字体以宋体显�C�，让java桌面应用�E�序更美�?nbsp; 阅读全文

�I�白 2008-09-07 13:46 发表评论

Spring之BeanFactory与ApplicationConText区别

�I�白 — Sun, 22 Jun 2008 10:34:00 GMT
     使用BeanFactory从xml配置文�g加蝲bean:
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.FileSystemResource;

public class XmlConfigWithBeanFactory {

    public static void main(String[] args) {
        XmlBeanFactory factory = new XmlBeanFactory(new FileSystemResource(
                "build/beans.xml"));

    }
}

    使用ApplicationConText从xml配置文�g加蝲bean:

public class XmlConfigWithApplication{

    public static void main(String[] args){
        ApplicationContext application = new ClassPathXmlApplicationContext(beans.xml"));
         application.getBean("BeanName");
    }
}

    ApplicationContext和BeanFacotry相比,提供了更多的扩展功能�Q�但其主要区别在于后者是延迟加蝲,如果Bean的某一个属性没有注入，BeanFacotry加蝲后，直至�W�一�ơ��用调用getBean�Ҏ��才会抛出异常�Q�而ApplicationContext则在初始化自�w�是��验，�q�样有利于检查所依赖属性是否注入；所以通常情况下我们选择使用ApplicationContext.

�I�白 2008-06-22 18:34 发表评论

使用Xfire开发WebService

�I�白 — Fri, 20 Jun 2008 04:10:00 GMT
MyEclipse中和许多�|�站的WebService教程以HelloWord��Z��,内容比较��?在实际的��目应用中大多都是对象和集合,现在我们扩展�?使用webservice传递对�?字符�?集合;
下面是我们设计的webservice的接�?
1package com.test.service;
2
3import java.util.List;
4
5public interface IPerson {
6    //�Ҏ��用户名获取密�?/span>
7    public String getPassword(String name);
8    //�Ҏ��用户名获取Person对象
9    public Person getPersonByName();
10    //获取全部成员
11    public List<Person> getAllPerson();
12}

其中有三个方法包含了传�?String,Object,List集合;
2,�q�里我们实现接口中定义的业务逻辑

package com.test.service;

import java.util.LinkedList;
import java.util.List;

public class PersonImpl implements IPerson {


    public String getPassword(String name) {

        return "Password";
    }

    public Person getPersonByName() {

        return new Person("ObjectName","ObjectPass");
    }

    public java.util.List<Person> getAllPerson(){

        List list = new LinkedList();
        list.add(new Person("One","PassOne"));
        list.add(new Person("Two","PassTwo"));
        list.add(new Person("Three","PassThree"));
        return list;
    }
}

在实际应用中比较复杂,可能用调用持久层的Dao,�q�回需要的�l�果,�q�里我们直接创徏一个模拟数�?下面是实现类中用到的对象

1package com.test.service;
2
3public class Person {
4    private String name;
5    private String password;
6
7    public Person() {
8        super();
9    }
10    public Person(String name, String password){
11        super();
12        this.name = name;
13        this.password = password;
14    }
15    public String getPassword(){
16        return password;
17    }
18    public void setPassword(String password){
19        this.password = password;
20    }
21}
22

3,�~�写XFire要求的WebSevice定义描述文�g�Q�如下：

xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://xfire.codehaus.org/config/1.0">

    <service>
        <name>Personname>
        <serviceClass>com.test.service.IPersonserviceClass>
        <implementationClass>
            com.test.service.PersonImpl
        implementationClass>
        <style>wrappedstyle>
        <use>literaluse>
        <scope>applicationscope>
    service>beans>
本文件的攄��位置很关�?此文件放在src/META-INF/xfire/services.xml�Q�如果��用MyEclipse新徏的不是webapplication,而是webservice��目,�q�一步就省去自己�~�写�?�~�译时会自动�~�译到classes的相应目录下面。web.z
5,�~�译xml,定义XfireConfigableServlet

1xml version="1.0" encoding="UTF-8"?>
2<web-app xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.4" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee   http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
3  <servlet>
4    <servlet-name>XFireServletservlet-name>
5    <servlet-class>org.codehaus.xfire.transport.http.XFireConfigurableServletservlet-class>
6    <load-on-startup>0load-on-startup>
7  servlet>
8  <servlet-mapping>
9    <servlet-name>XFireServletservlet-name>
10    <url-pattern>/services/*url-pattern>
11  servlet-mapping>
12  <welcome-file-list>
13    <welcome-file>index.jspwelcome-file>
14  welcome-file-list>
15web-app>
16
17
所有的工作都已�l�作完，接下来在部��v在tomcate下，启动服务器，在地址栏键入：http://127.0.0.1:8080/MyWebService/srevice/Person?wsdl
如果出现xml描述文�g��成功了�Q?br />

�I�白 2008-06-20 12:10 发表评论

`T`	`get()` �q�回此线�E�局部变量的当前�U�程副本中的倹{�?/td>
`protected T`	`initialValue()` �q�回此线�E�局部变量的当前�U�程�?#8220;初始�?#8221;�?/td>
`void`	`remove()` �U�除此线�E�局部变量当前线�E�的倹{�?/td>
`void`	`set(T value)` ��此�U�程局部变量的当前�U�程副本中的��D��\|��ؓ指定倹{�?/td>

属性摘�?/strong>
`protected List<Pattern>`	`excludedPatterns`
`protected ExecuteOperations`	`execute`
`protected PrepareOperations`	`prepare`

�Ҏ��摘要
`void`	`destroy()` �l�承自Filter�Q�用于资源释�?/td>
`void`	`doFilter(ServletRequest req, ServletResponse res, FilterChain chain)` �l�承自Filter�Q�执行方�?/td>
`void`	`init(FilterConfig filterConfig)` �l�承自Filter�Q�初始化参数
`protected void`	`postInit(Dispatcher dispatcher, FilterConfig filterConfig)` Callback for post initialization�Q�一个空的方法，用于�Ҏ��回调初始化）

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Spring JDBC Framework详解——批量JDBC操作、ORM映射

Tomcat6.x目录与server.xml详解

深入���出ThreadLocal

ThreadLocal�C�Z��

探究Struts2�q�行机制�Q�StrutsPrepareAndExecuteFilter 源码剖析

NetBean6字体配置

Spring之BeanFactory与ApplicationConText区别

使用Xfire开发WebService

深入��出ThreadLocal