利用Filter過濾器，做了一個簡易的登錄功能：
項目目錄結構：
index.jsp:
<%@ 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="http://localhost:8080/filter-login/loginServlet" method="post">
用戶名：<input type="text" name="user">
密碼：<input type="text" name="password">
<input type="submit" value="登錄">
</form>
</body>
</html>login-success.jsp:
<%@ 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>
<h3>登錄成功！！！</h3>
</body>
</html>loginServlet.java
package com.filter.servlet;
import java.io.IOException;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.filter.filter.PasswordFilter;
import com.filter.filter.UsernameFilter;
/**
* Servlet implementation class loginServlet
*/
@WebServlet("/loginServlet")
public class loginServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public loginServlet() {
super();
// TODO Auto-generated constructor stub
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doPost(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.getRequestDispatcher("/login-success.jsp").forward(request,response);
}
}
UsernameFilter.java:
package com.filter.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;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet Filter implementation class UsernameFilter
*/
@WebFilter("/UsernameFilter")
public class UsernameFilter implements Filter {
/**
* Default constructor.
*/
public UsernameFilter() {
// TODO Auto-generated constructor stub
}
public void destroy() {
// TODO Auto-generated method stub
}
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
if (request.getParameter("user").equals("admin")){
chain.doFilter(request, response);
System.out.println("登錄名放行");
}
else{
request.getRequestDispatcher("/index.jsp").forward(request,response);
}
}
public void init(FilterConfig fConfig) throws ServletException {
// TODO Auto-generated method stub
}
}PasswordFilter.java:
package com.filter.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;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet Filter implementation class PasswordFilter
*/
@WebFilter("/PasswordFilter")
public class PasswordFilter implements Filter {
public PasswordFilter() {
// TODO Auto-generated constructor stub
}
public void destroy() {
// TODO Auto-generated method stub
}
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
if (request.getParameter("password").equals("123123")){
chain.doFilter(request, response);
System.out.println("密碼放行");
}
else{
request.getRequestDispatcher("/index.jsp").forward(request,response);
}
}
public void init(FilterConfig fConfig) throws ServletException {
// TODO Auto-generated method stub
}
}