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<p>练习好多天了，还是不会用博客编辑器,原谅我!!</p>
组织每天监督，今天学习的是filter过滤器
在很多国内博客里找不到具体的实例，所以到外国网站上找了一个来练习
利用filter实现了登陆页面验证功能
没有很多的文字叙述，我打算周末补充心得，每天下班找代码，敲代码。重要的事说三遍（总结：总结：总结：）
一定要会总结，不然一天都白费了
AuthenticationFilter.java
package com.journaldev.servlet.filters;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
@WebFilter("/AuthenticationFilter")
public class AuthenticationFilter implements Filter{
private ServletContext context;
public void init(FilterConfig fConfig) throws ServletException{
this.context = fConfig.getServletContext();
this.context.log("AuthenticationFilter initialized");
}
public void doFilter(ServletRequest request,ServletResponse response,FilterChain chain) throws IOException,ServletException{
HttpServletRequest req = (HttpServletRequest) request;
HttpServletResponse res = (HttpServletResponse) response;
String uri = req.getRequestURI();
this.context.log("Requested Resource::" + uri);
HttpSession session = req.getSession(false);
if(session == null && !(uri.endsWith("html") || uri.endsWith("LoginServlet"))){
this.context.log("Unauthorized access request");
res.sendRedirect("login.html");
}else{
chain.doFilter(request, response);
}
}
public void destroy(){
}
}
RequestLoggingFilter.java
package com.journaldev.servlet.filters;
import java.io.IOException;
import java.util.Enumeration;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
@WebFilter("/RequestLoggingFilter")
public class RequestLoggingFilter implements Filter{
private ServletContext context;
public void init(FilterConfig fConfig) throws ServletException {
this.context = fConfig.getServletContext();
this.context.log("RequestLoggingFilter initialized");
}
public void doFilter(ServletRequest request,ServletResponse response, FilterChain chain)throws IOException,ServletException{
HttpServletRequest req = (HttpServletRequest) request;
Enumeration<String> params = req.getParameterNames();
while(params.hasMoreElements()){
String name = params.nextElement();
String value = request.getParameter(name);
this.context.log(req.getRemoteAddr() + "::Request Paramet::{"+name+"="+value+"}");
}
Cookie[] cookies = req.getCookies();
if(cookies != null){
for(Cookie cookie : cookies){
this.context.log(req.getRemoteAddr() + "::Cookie{"+cookie.getName()+","+cookie.getValue()+"}");
}
}
chain.doFilter(request, response);
}
public void destroy(){
}
}
LoginServlet.java
package com.journaldev.servlet.session;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet{
private static final long serialVersionUID = 1L;
private final String userID = "admin";
private final String password = "password";
protected void doPost(HttpServletRequest request,
HttpServletResponse response)throws ServletException, IOException{
String user = request.getParameter("user");
String pwd = request.getParameter("pwd");
if(userID.equals(user)&&password.equals(pwd)){
HttpSession session = request.getSession();
session.setAttribute("user", "Pankaj");
session.setMaxInactiveInterval(30*60);
Cookie userName = new Cookie("user",user);
userName.setMaxAge(30*60);
response.addCookie(userName);
response.sendRedirect("LoginSuccess.jsp");
}else{
RequestDispatcher rd = getServletContext().getRequestDispatcher("/login.html");
PrintWriter out = response.getWriter();
out.println("<font color=red>Either user name or password is wrong.</font>");
rd.include(request, response);
}
}
}
LogoutServlet.java
package com.journaldev.servlet.session;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
@WebServlet("/LogoutServlet")
public class LogoutServlet extends HttpServlet{
private static final long serialVersionUID = 1L;
protected void doPost(HttpServletRequest request,HttpServletResponse response)throws ServletException,IOException{
response.setContentType("text/html");
Cookie[] cookies = request.getCookies();
if(cookies != null){
for(Cookie cookie : cookies){
if(cookie.getName().equals("JSESSIONID")){
System.out.println("JSESSIONID="+cookie.getValue());
break;
}
}
}
HttpSession session = request.getSession(false);
System.out.println("User="+session.getAttribute("user"));
if(session != null){
session.invalidate();
}
response.sendRedirect("login.html");
}
}
CheckoutPage.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>
<%
String userName = null;
String sessionID = null;
Cookie[] cookies = request.getCookies();
if(cookies != null){
for(Cookie cookie : cookies){
if(cookie.getName().equals("user")) userName = cookie.getValue();
}
}
%>
<h3>Hi <%=userName %>, do the checkout.</h3>
<br>
<form action="LogoutServlet" method="post">
<input type="submit" value="Logout">
</form>
</body>
</html>
login.html
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>Insert title here</title> </head> <body> <form action="LoginServlet" method="post"> Username:<input type="text" name="user"> <br> Password:<input type="password" name="pwd"> <br> <input type="submit" value="Login"> </form> </body> </html>
LoginSuccess.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>
<%
//allow access only if session exists
String user = (String) session.getAttribute("user");
String userName = null;
String sessionID = null;
Cookie[] cookies = request.getCookies();
if(cookies != null){
for(Cookie cookie:cookies){
if(cookie.getName().equals("user")) userName = cookie.getValue();
if(cookie.getName().equals("JSESSIONID")) sessionID = cookie.getValue();
}
}
%>
<h3>Hi <%=userName %>, Login successful.Your Session ID=<%=sessionID %></h3>
<br>
<a href="CheckoutPage.jsp">Checkout Page</a>
<form action="LogoutServlet" method="post">
<input type="submit" value="Logout">
</form>
</body>
</html>
展示结果图片：
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原文地址：http://www.cnblogs.com/song-1995/p/5008783.html
