1. 串联Servlet过滤器的工作流程
2. 创建两个过滤器 MyFilter1和MyFilter2
1） MyFilter1
package com.example.filter;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebFilter;
/**
* Servlet Filter implementation class MyFilter1
*/
//@WebFilter("/MyFilter1")
public class MyFilter1 implements Filter {
/**
* Default constructor.
*/
public MyFilter1() {
// TODO Auto-generated constructor stub
}
/**
* @see Filter#destroy()
*/
public void destroy() {
// TODO Auto-generated method stub
}
/**
* @see Filter#doFilter(ServletRequest, ServletResponse, FilterChain)
*/
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
// TODO Auto-generated method stub
// place your code here
System.out.println("dofilter 1");
// pass the request along the filter chain
chain.doFilter(request, response);
System.out.println("after dofilter 1");
}
/**
* @see Filter#init(FilterConfig)
*/
public void init(FilterConfig fConfig) throws ServletException {
// TODO Auto-generated method stub
}
}
2） MyFilter 2
package com.example.filter;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebFilter;
/**
* Servlet Filter implementation class MyFilter2
*/
//@WebFilter("/MyFilter2")
public class MyFilter2 implements Filter {
/**
* Default constructor.
*/
public MyFilter2() {
// TODO Auto-generated constructor stub
}
/**
* @see Filter#destroy()
*/
public void destroy() {
// TODO Auto-generated method stub
}
/**
* @see Filter#doFilter(ServletRequest, ServletResponse, FilterChain)
*/
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
// TODO Auto-generated method stub
// place your code here
System.out.println("dofilter 2");
// pass the request along the filter chain
chain.doFilter(request, response);
System.out.println("after dofilter 2");
}
/**
* @see Filter#init(FilterConfig)
*/
public void init(FilterConfig fConfig) throws ServletException {
// TODO Auto-generated method stub
}
}
3) 在web.xml 中配置过滤器
<filter>
<filter-name>MyFilter1</filter-name>
<filter-class>com.example.filter.MyFilter1</filter-class>
</filter>
<filter-mapping>
<filter-name>MyFilter1</filter-name>
<url-pattern>/InfoServlet</url-pattern>
</filter-mapping>
<filter>
<filter-name>MyFilter2</filter-name>
<filter-class>com.example.filter.MyFilter2</filter-class>
</filter>
<filter-mapping>
<filter-name>MyFilter2</filter-name>
<url-pattern>/InfoServlet</url-pattern>
</filter-mapping>
4） 创建jsp页面
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="InfoServlet">
username: <input type="text" name="username"><br>
<input type="submit" value="submit">
</form>
</body>
</html>
5） 创建InfoServlet
package com.example.servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class InfoServlet
*/
@WebServlet("/InfoServlet")
public class InfoServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public InfoServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println(request.getParameter("username"));
request.getRequestDispatcher("infoResult.jsp").forward(request, response);
}
}
6） 显示结果
打印的顺序与过滤器的工作流程一致