servlet3.0

1、之前我们创建的项目是servlet2.5，之前的版本，servlet、filter、listener需要配置web.xml

在servlet3.0的时候，没有web.xml，提供注解开发。

servlet注解：@WebServlet(name = "ServletDemo",urlPatterns ={"/demo1","/demo21"})

filter注解：@WebFilter(urlPatterns = "/demo1")

listener注解：@WebListener()

例子：

 package jd.com.test;

 import javax.servlet.ServletException;
 import javax.servlet.annotation.WebServlet;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import java.io.IOException;

 @WebServlet(name = "ServletDemo",urlPatterns ={"/demo1","/demo21"} )
 public class ServletDemo extends HttpServlet {
     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
         doGet(request,response);
     }

     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
             System.out.println("访问demo1了。");
     }
 }

 package jd.com.test;

 import javax.servlet.*;
 import javax.servlet.annotation.WebFilter;
 import java.io.IOException;

 @WebFilter(urlPatterns = "/demo1")
 public class MyFilter implements Filter {

     @Override
     public void init(FilterConfig filterConfig) throws ServletException {

     }

     @Override
     public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
         System.out.println("来到Myfilter");
         filterChain.doFilter(servletRequest,servletResponse);
     }

     @Override
     public void destroy() {

     }
 }