Servlet 3.0
[转自：http://blog.csdn.net/xiazdong/article/details/7208316]
Servlet 3.0 新特性概览
1.Servlet、Filter、Listener无需在web.xml中进行配置，可以通过Annotation进行配置；
2.模块化编程，即将各个Servlet模块化，将配置文件也分开配置。
3.Servlet异步处理，应对复杂业务处理；
4.异步Listener，对于异步处理的创建、完成等进行监听；
5. 文件上传API简化；
tomcat 7.0.X 支持Servlet 3.0
原本Servlet开发完后，必须在web.xml中配置如下代码：
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<![if !supportLists]>1. <![endif]><servlet>
<![if !supportLists]>2. <![endif]> <servlet-name></servlet-name>
<![if !supportLists]>3. <![endif]> <servler-class></servlet-class>
<![if !supportLists]>4. <![endif]> <load-on-startup></load-on-startup>
<![if !supportLists]>5. <![endif]> <init-param>
<![if !supportLists]>6. <![endif]> <param-name></param-name>
<![if !supportLists]>7. <![endif]> <param-value></param-value>
<![if !supportLists]>8. <![endif]> </init-param>
<![if !supportLists]>9. <![endif]></servlet>
<![if !supportLists]>10.<![endif]><servlet-mapping>
<![if !supportLists]>11.<![endif]> <servlet-name></servlet-name>
<![if !supportLists]>12.<![endif]> <url-pattern></url-pattern>
<![if !supportLists]>13.<![endif]></servlet-mapping>
现在只需要在java源文件的Servlet类前面加上：
@WebServlet(name="",urlPatterns={""},initParams={@WebInitParam(name="",value=""),loadOnStartup=1})
public class FirstServlet extends HttpServlet{}
代码示例：
实现一个最简单的Servlet。
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<![if !supportLists]>1. <![endif]>package org.servlet;
<![if !supportLists]>2. <![endif]>import java.io.*;
<![if !supportLists]>3. <![endif]>import javax.servlet.*;
<![if !supportLists]>4. <![endif]>import javax.servlet.http.*;
<![if !supportLists]>5. <![endif]>import javax.servlet.annotation.*;
<![if !supportLists]>6. <![endif]>/*
<![if !supportLists]>7. <![endif]> name == <servlet-name>
<![if !supportLists]>8. <![endif]> urlPatterns == <url-pattern>,
<![if !supportLists]>9. <![endif]> loadOnStartup == <load-on-startup>
<![if !supportLists]>10.<![endif]> initParam == <init-param>
<![if !supportLists]>11.<![endif]> name == <param-name>
<![if !supportLists]>12.<![endif]> value == <param-value>
<![if !supportLists]>13.<![endif]>*/
<![if !supportLists]>14.<![endif]>@WebServlet(name="HelloServlet" ,urlPatterns={"/HelloServlet"},loadOnStartup=1,
<![if !supportLists]>15.<![endif]> initParams={
<![if !supportLists]>16.<![endif]> @WebInitParam(name="name",value="xiazdong"),
<![if !supportLists]>17.<![endif]> @WebInitParam(name="age",value="20")
<![if !supportLists]>18.<![endif]> })
<![if !supportLists]>19.<![endif]>public class HelloServlet extends HttpServlet{
<![if !supportLists]>20.<![endif]> public void init(ServletConfig config)throws ServletException{
<![if !supportLists]>21.<![endif]> super.init(config);
<![if !supportLists]>22.<![endif]> }
<![if !supportLists]>23.<![endif]> public void service(HttpServletRequest request,HttpServletResponse response)throws ServletException,IOException{
<![if !supportLists]>24.<![endif]> request.setCharacterEncoding("GBK");
<![if !supportLists]>25.<![endif]> ServletConfig config = getServletConfig();
<![if !supportLists]>26.<![endif]> PrintWriter out = response.getWriter();
<![if !supportLists]>27.<![endif]> out.println("<html>");
<![if !supportLists]>28.<![endif]> out.println("<body>");
<![if !supportLists]>29.<![endif]> out.println("Hello world"+"<br />");
<![if !supportLists]>30.<![endif]> out.println(config.getInitParameter("name"));
<![if !supportLists]>31.<![endif]> out.println("</body>");
<![if !supportLists]>32.<![endif]> out.println("</html>");
<![if !supportLists]>33.<![endif]> }
<![if !supportLists]>34.<![endif]>}
这样的话只需要将class文件放入WEB-INF\classes 中，不需要再web.xml中作任何改动就完成部署；
原本Filter的配置如下：
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<![if !supportLists]>1. <![endif]><filter>
<![if !supportLists]>2. <![endif]> <filter-name></filter-name>
<![if !supportLists]>3. <![endif]> <filter-class></filter-class>
<![if !supportLists]>4. <![endif]><filter>
<![if !supportLists]>5. <![endif]><filter-mapping>
<![if !supportLists]>6. <![endif]> <filter-name></filter-name>
<![if !supportLists]>7. <![endif]> <url-pattern></url-pattern>
<![if !supportLists]>8. <![endif]></filter-mapping>
<![if !supportLists]>9. <![endif]>
<![if !supportLists]>10.<![endif]>
现在只需要在java源文件的Filter类前面加上
@WebFilter(filterName="",urlPattern={"/"});
原本在web.xml中配置如下：
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<![if !supportLists]>1. <![endif]><listener>
<![if !supportLists]>2. <![endif]> <listener-class></listener-class>
<![if !supportLists]>3. <![endif]></listener>
<![if !supportLists]>4. <![endif]>
<![if !supportLists]>5. <![endif]>
现在只需要在java源文件的Listener类前面加上@WebListener即可；
原本一个web应用的任何配置都需要在web.xml中进行，因此会使得web.xml变得很混乱，而且灵活性差，因此Servlet 3.0可以将每个Servlet、Filter、Listener打成jar包，然后放在WEB-INF\lib中；注意各自的模块都有各自的配置文件，这个配置文件的名称为 web-fragment.xml ;
制作一个Servlet模块的步骤：
1.编写Servlet，并编译；
2.将此编译class文件及所在包通过jar包命令打成jar包；
3.将此jar包用winrar打开，并将其中的META-INF中的manifest删除并添加 web-fragment.xml；
4.将此jar包放入WEB-INF\lib中即可；
web-fragment.xml注意点：
1.根元素为<web-fragment>;
2.<name></name>表示模块名称；
3.<ordering></ordering>是此模块的加载顺序；
4.<before><others/></before>表示第一个加载；
5.<after><name>A</name></after>表示比A后面加载；
6.可以在里面部署listener、filter、servlet
当然可以不设置任何的模块加载顺序；
代码示例：
配置两个listener模块；
FirstListener.java
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<![if !supportLists]>1. <![endif]>
<![if !supportLists]>2. <![endif]>
<![if !supportLists]>3. <![endif]>package org.listener;
<![if !supportLists]>4. <![endif]>import javax.servlet.annotation.*;
<![if !supportLists]>5. <![endif]>import javax.servlet.http.*;
<![if !supportLists]>6. <![endif]>import javax.servlet.*;
<![if !supportLists]>7. <![endif]>import java.util.*;
<![if !supportLists]>8. <![endif]>import java.sql.*;
<![if !supportLists]>9. <![endif]>import javax.naming.*;
<![if !supportLists]>10.<![endif]>public class FirstListener implements ServletRequestListener{
<![if !supportLists]>11.<![endif]> public void requestInitialized(ServletRequestEvent event){
<![if !supportLists]>12.<![endif]> System.out.println("FirstListener created");
<![if !supportLists]>13.<![endif]> }
<![if !supportLists]>14.<![endif]> public void requestDestroyed(ServletRequestEvent event){
<![if !supportLists]>15.<![endif]> System.out.println("FirstListener destroyed");
<![if !supportLists]>16.<![endif]> }
<![if !supportLists]>17.<![endif]>}
FirstListener 的 web-fragment.xml内容：
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<![if !supportLists]>1. <![endif]><?xml version="1.0" encoding="ISO-8859-1"?>
<![if !supportLists]>2. <![endif]><web-fragment xmlns="http://java.sun.com/xml/ns/javaee"
<![if !supportLists]>3. <![endif]> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
<![if !supportLists]>4. <![endif]> xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
<![if !supportLists]>5. <![endif]> <A href="http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"">http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
<![if !supportLists]>6. <![endif]> version="3.0">
<![if !supportLists]>7. <![endif]> <name>FirstListener</name>
<![if !supportLists]>8. <![endif]> <listener>
<![if !supportLists]>9. <![endif]> <listener-class>org.listener.FirstListener</listener-class>
<![if !supportLists]>10.<![endif]> </listener>
<![if !supportLists]>11.<![endif]> <ordering>
<![if !supportLists]>12.<![endif]> <before>
<![if !supportLists]>13.<![endif]> <others/>
<![if !supportLists]>14.<![endif]> </before>
<![if !supportLists]>15.<![endif]> </ordering>
<![if !supportLists]>16.<![endif]></web-fragment>
SecondListener.java
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<![if !supportLists]>1. <![endif]>package org.listener;
<![if !supportLists]>2. <![endif]>import javax.servlet.annotation.*;
<![if !supportLists]>3. <![endif]>import javax.servlet.http.*;
<![if !supportLists]>4. <![endif]>import javax.servlet.*;
<![if !supportLists]>5. <![endif]>import java.util.*;
<![if !supportLists]>6. <![endif]>import java.sql.*;
<![if !supportLists]>7. <![endif]>import javax.naming.*;
<![if !supportLists]>8. <![endif]>public class SecondListener implements ServletRequestListener{
<![if !supportLists]>9. <![endif]> public void requestInitialized(ServletRequestEvent event){
<![if !supportLists]>10.<![endif]> System.out.println("SecondListener created");
[java] view plaincopy
<![if !supportLists]>1. <![endif]> }
<![if !supportLists]>2. <![endif]> public void requestDestroyed(ServletRequestEvent event){
<![if !supportLists]>3. <![endif]> System.out.println("SecondListener destroyed");
<![if !supportLists]>4. <![endif]> }
<![if !supportLists]>5. <![endif]>}
SecondListener的 web-fragment.xml内容是：
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<![if !supportLists]>1. <![endif]><?xml version="1.0" encoding="ISO-8859-1"?>
<![if !supportLists]>2. <![endif]><web-fragment xmlns="http://java.sun.com/xml/ns/javaee"
<![if !supportLists]>3. <![endif]> xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
<![if !supportLists]>4. <![endif]> xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
<![if !supportLists]>5. <![endif]> <A href="http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"">http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
<![if !supportLists]>6. <![endif]> version="3.0">
<![if !supportLists]>7. <![endif]> <name>SecondListener</name>
<![if !supportLists]>8. <![endif]> <listener>
[html] view plaincopy
<![if !supportLists]>1. <![endif]> <listener-class>org.listener.SecondListener</listener-class>
<![if !supportLists]>2. <![endif]></listener>
<![if !supportLists]>3. <![endif]><ordering>
<![if !supportLists]>4. <![endif]> <after>
<![if !supportLists]>5. <![endif]> <name>FirstListener</name>
<![if !supportLists]>6. <![endif]> </after>
<![if !supportLists]>7. <![endif]></ordering>
<![if !supportLists]>8. <![endif]>b-fragment>
然后分别打成jar包，放入 WEB-INF\lib中即可；
随便访问一个web应用，然后发现 tomcat控制台输出：
看出先加载FirstListener，再加载SecondListener；
Servlet在MVC中作为控制器，控制器负责分发任务给MODEL完成，然后把结果交给JSP显示；
而如果有许多MODEL，其中有一个MODEL处理时间很长，则会导致整个页面的显示很慢；
异步处理关键点：将复杂业务处理另外开一个线程，而Servlet将执行好的业务先送往jsp输出，等到耗时业务做完后再送往JSP页面；
一句话：先显示一部分，再显示一部分；
异步处理Servlet的注意点是：
1.需要在Annotation中注明 asyncSupported=true;
[java] view plaincopy
<![if !supportLists]>1. <![endif]>package org.sync;
<![if !supportLists]>2. <![endif]>import javax.servlet.*;
<![if !supportLists]>3. <![endif]>import javax.servlet.http.*;
<![if !supportLists]>4. <![endif]>import javax.servlet.annotation.*;
<![if !supportLists]>5. <![endif]>import java.io.*;
<![if !supportLists]>6. <![endif]>@WebServlet(name="AsyncServlet",urlPatterns={"/AsyncServlet"},asyncSupported=true)
<![if !supportLists]>7. <![endif]>public class AsyncServlet extends HttpServlet{
<![if !supportLists]>8. <![endif]> public void service(HttpServletRequest request,HttpServletResponse response)throws ServletException,IOException{
<![if !supportLists]>9. <![endif]> request.setCharacterEncoding("GBK");
<![if !supportLists]>10.<![endif]> response.setContentType("text/html;charset=GBK");
<![if !supportLists]>11.<![endif]> PrintWriter out = response.getWriter();
<![if !supportLists]>12.<![endif]> out.println("<html>");
<![if !supportLists]>13.<![endif]> out.println("<body>");
<![if !supportLists]>14.<![endif]> out.println("====页面开始====<hr />");
<![if !supportLists]>15.<![endif]> AsyncContext actx = request.startAsync();
<![if !supportLists]>16.<![endif]> actx.setTimeout(30*3000);
<![if !supportLists]>17.<![endif]> actx.start(new MyThread(actx));
<![if !supportLists]>18.<![endif]> out.println("====页面结束====<hr />");
<![if !supportLists]>19.<![endif]> out.println("</body>");
<![if !supportLists]>20.<![endif]> out.println("</html>");
<![if !supportLists]>21.<![endif]> out.flush();
<![if !supportLists]>22.<![endif]> }
<![if !supportLists]>23.<![endif]>}
<![if !supportLists]>24.<![endif]>class MyThread implements Runnable{
<![if !supportLists]>25.<![endif]> private AsyncContext actx;
<![if !supportLists]>26.<![endif]> public MyThread(AsyncContext actx){
<![if !supportLists]>27.<![endif]> this.actx = actx;
<![if !supportLists]>28.<![endif]> }
<![if !supportLists]>29.<![endif]> public void run(){
<![if !supportLists]>30.<![endif]> try{
<![if !supportLists]>31.<![endif]> Thread.sleep(5*1000); //消耗5秒
<![if !supportLists]>32.<![endif]> actx.dispatch("/1.jsp");
<![if !supportLists]>33.<![endif]> }
<![if !supportLists]>34.<![endif]> catch(Exception e){}
<![if !supportLists]>35.<![endif]> }
<![if !supportLists]>36.<![endif]>}
1.jsp
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<![if !supportLists]>1. <![endif]><%@ page contentType="text/html;charset=GBK" pageEncoding="GBK" session="false"%>
<![if !supportLists]>2. <![endif]><html>
<![if !supportLists]>3. <![endif]> <body>
<![if !supportLists]>4. <![endif]> <%
<![if !supportLists]>5. <![endif]> out.println("======复杂业务方法====");
<![if !supportLists]>6. <![endif]> %>
<![if !supportLists]>7. <![endif]> </body>
<![if !supportLists]>8. <![endif]></html>
异步监听器用来监听异步处理事件；即“三”中讲到的知识点；
此监听器类似于ServletContextListener的机制；
只需要实现AsyncListener接口即可；
此接口有4个方法：
public void
onStartAsync(AsyncEvent event)throws IOException;
public void onComplete(AsyncEvent event);
public void onTimeout(AsyncEvent event);
public void onError(AsyncEvent event);
以下是监听器实现的代码：
[java] view plaincopy
<![if !supportLists]>1. <![endif]>package org.listener;
<![if !supportLists]>2. <![endif]>import javax.servlet.annotation.*;
<![if !supportLists]>3. <![endif]>import javax.servlet.http.*;
<![if !supportLists]>4. <![endif]>import javax.servlet.*;
<![if !supportLists]>5. <![endif]>import java.util.*;
<![if !supportLists]>6. <![endif]>import java.sql.*;
<![if !supportLists]>7. <![endif]>import javax.naming.*;
<![if !supportLists]>8. <![endif]>import java.io.*;
<![if !supportLists]>9. <![endif]>public class MyListener implements AsyncListener{
<![if !supportLists]>10.<![endif]> public void onStartAsync(AsyncEvent event)throws IOException{}
<![if !supportLists]>11.<![endif]> public void onComplete(AsyncEvent event){
<![if !supportLists]>12.<![endif]> System.out.println("-----------------------Complete");
<![if !supportLists]>13.<![endif]> }
<![if !supportLists]>14.<![endif]> public void onTimeout(AsyncEvent event){
<![if !supportLists]>15.<![endif]> }
<![if !supportLists]>16.<![endif]> public void onError(AsyncEvent event){}
<![if !supportLists]>17.<![endif]>}
在Servlet异步处理处添加：
actx.addListener(new MyListener())；就可以添加监听器，每当异步处理完成时就会触发onComplete()事件，输出Complete；
原本文件上传时通过 common-fileupload或者SmartUpload，上传比较麻烦，在Servlet 3.0 中不需要导入任何第三方jar包，并且提供了很方便进行文件上传的功能；
注意点：
1. html中 <input type="file">表示文件上传控件；
2. form的 enctype="multipart/form-data"；
3.在Servlet类前加上 @MultipartConfig
4.request.getPart()获得；
下面是一个文件上传的例子：
upload.html
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<![if !supportLists]>1. <![endif]><html>
<![if !supportLists]>2. <![endif]> <body>
<![if !supportLists]>3. <![endif]> <form method="post" enctype="multipart/form-data" action="upload">
<![if !supportLists]>4. <![endif]> <input type="file" id="file" name="file"/>
<![if !supportLists]>5. <![endif]> <input type="text" id="name" name="name"/>
<![if !supportLists]>6. <![endif]> <input type="submit" value="提交"/>
<![if !supportLists]>7. <![endif]> </form>
<![if !supportLists]>8. <![endif]> </body>
<![if !supportLists]>9. <![endif]></html>
UploadServlet.java
[java] view plaincopy
<![if !supportLists]>1. <![endif]>package org.servlet;
<![if !supportLists]>2. <![endif]>import java.io.*;
<![if !supportLists]>3. <![endif]>import javax.servlet.*;
<![if !supportLists]>4. <![endif]>import javax.servlet.http.*;
<![if !supportLists]>5. <![endif]>import javax.servlet.annotation.*;
<![if !supportLists]>6. <![endif]>
<![if !supportLists]>7. <![endif]>@WebServlet(name="UploadServlet" ,urlPatterns={"/upload"})
<![if !supportLists]>8. <![endif]>@MultipartConfig
<![if !supportLists]>9. <![endif]>public class UploadServlet extends HttpServlet{
<![if !supportLists]>10.<![endif]> public void init(ServletConfig config)throws ServletException{
<![if !supportLists]>11.<![endif]> super.init(config);
<![if !supportLists]>12.<![endif]> }
<![if !supportLists]>13.<![endif]> public void service(HttpServletRequest request,HttpServletResponse response)throws ServletException,IOException{
<![if !supportLists]>14.<![endif]> Part part = request.getPart("file");
<![if !supportLists]>15.<![endif]> PrintWriter out = response.getWriter();
<![if !supportLists]>16.<![endif]> out.println("此文件的大小："+part.getSize()+"<br />");
<![if !supportLists]>17.<![endif]> out.println("此文件类型："+part.getContentType()+"<br />");
<![if !supportLists]>18.<![endif]> out.println("文本框内容："+request.getParameter("name")+"<br />");
<![if !supportLists]>19.<![endif]> out.println(UploadUtil.getFileName(part)+"<br />");
<![if !supportLists]>20.<![endif]> part.write("F:\\1."+UploadUtil.getFileType(part));
<![if !supportLists]>21.<![endif]> }
<![if !supportLists]>22.<![endif]>}
UploadUtil.java
由于在Servlet 3.0中很难获取上传文件的类型，因此我写了两个工具类，可以方便开发；
[java] view plaincopy
<![if !supportLists]>1. <![endif]>/**
<![if !supportLists]>2. <![endif]> * 此工具类只适用于Servlet 3.0
<![if !supportLists]>3. <![endif]> * 为了弥补 Servlet 3.0 文件上传时获取文件类型的困难问题
<![if !supportLists]>4. <![endif]> *
<![if !supportLists]>5. <![endif]> * @author xiazdong
<![if !supportLists]>6. <![endif]> */
<![if !supportLists]>7. <![endif]>import javax.servlet.http.*;
<![if !supportLists]>8. <![endif]>public class UploadUtil{
<![if !supportLists]>9. <![endif]> public static String getFileType(Part p){
<![if !supportLists]>10.<![endif]> String name = p.getHeader("content-disposition");
<![if !supportLists]>11.<![endif]> String fileNameTmp = name.substring(name.indexOf("filename=")+10);
<![if !supportLists]>12.<![endif]> String type = fileNameTmp.substring(fileNameTmp.indexOf(".")+1,fileNameTmp.indexOf("\""));
<![if !supportLists]>13.<![endif]> return type;
<![if !supportLists]>14.<![endif]> }
<![if !supportLists]>15.<![endif]> public static String getFileName(Part p){
<![if !supportLists]>16.<![endif]> String name = p.getHeader("content-disposition");
<![if !supportLists]>17.<![endif]> String fileNameTmp = name.substring(name.indexOf("filename=")+10);
<![if !supportLists]>18.<![endif]> String fileName = fileNameTmp.substring(0,fileNameTmp.indexOf("\""));
<![if !supportLists]>19.<![endif]> return fileName;
<![if !supportLists]>20.<![endif]> }
<![if !supportLists]>21.<![endif]>}
<![if !supportLists]>22.<![endif]>
<![if !supportLists]>23.<![endif]>
<![if !supportLists]>24.<![endif]>
posted on 2013-11-02 17:51 ONLY LOVE PROGRAME 阅读(399) 评论(0) 编辑 收藏 举报
