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() {

    }
}