Servlet3.0新特性---注解

1.servlet3.0作为J2EE 6规范一部分，随j2EE6一起发布，并且tomcat7已经完全支持。

2.tomcat7(tomcat7 需要jdk1.6支持)已经完全支持servlet3.0,

3.web项目中添加对servlet3.0支持，

  将E:\apache-tomcat-7.0.26\lib下的jar包加入到web项目

  classpath中,可以不不加到web项目中WEB-INF/lib,保证编译时可用就行，部署到tomcat中，tomcat

  会使用自己servlet3.0支持的jar.完成后，将eclipse默认生成servlet2.5支持jar移除

4.修改WebRoot\WEB-INF\web.xml dtd文件，使其支持servlet3.0

   将tomcat7/conf/web.xml覆盖即可，删除不相关的部分，修改后的web.xml(主要是dtd)内容为:
  <?xml version="1.0" encoding="UTF-8"?>

<SPAN style="FONT-SIZE: small"><web-app xmlns="http://java.sun.com/xml/ns/javaee"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
                      http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
  version="3.0">
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app></SPAN>

<web-app xmlns="http://java.sun.com/xml/ns/javaee"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
                      http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
  version="3.0">
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

5.5.编写第一个servlet3.0的servlet,和之前差不了，就是用注解

  package com.darren.servlet;

<SPAN style="FONT-SIZE: small">import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebInitParam;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


@WebServlet(name="FirstServlet",urlPatterns={"/firstServlet","/MyServlet"},initParams={@WebInitParam(name="hello",value="world init....")})
@WebInitParam(name="paraName",value="paraValue")
public class FirstServlet extends HttpServlet {

    @Override
    public void init(ServletConfig config) throws ServletException {

        System.out.println(config.getInitParameter("paraName"));
        System.out.println(config.getInitParameter("hello"));
        //super.init(config);
    }

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        PrintWriter out = response.getWriter();
        out.println("hello,world...");
        out.close();
    }

}</SPAN>