這是一道j2ee老師佈置的題目!
題目意思就是通過login.jsp界面登錄,發送請求給UserLoginServlet, 然後再通過這個Servlet驗證權限看是否能通過。這裏爲了符合提議,就應該用到過濾器這個東西。
作業文件:
User存儲用戶信息,MyFilter是過濾類,GetRight類用來檢測賬號密碼是否正確,UserLoginServlet類是用來對登錄界面提交的請求進行相應處理的Servlet。QueryServlet和UpdateServlet不是重點,裏面就只out.print了一句話表示你的<a>訪問到了這個Servlet,還能單獨訪問以檢測session是否添加成功!index是登錄的目標界面,裏面有兩個鏈接,訪問兩個操作Servlet。
先看代碼,後面具體講解實現原理和操作流程:
這是web.xml的內容,對Servlet和過濾器進行了註冊:
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
<display-name>homework</display-name>
<servlet>
<servlet-name>UserLoginServlet</servlet-name>
<servlet-class>cn.jxufe.homework.servlet.UserLoginServlet</servlet-class>
</servlet>
<servlet>
<servlet-name>UpdateServlet</servlet-name>
<servlet-class>cn.jxufe.homework.servlet.UpdateServlet</servlet-class>
</servlet>
<servlet>
<servlet-name>QueryServlet</servlet-name>
<servlet-class>cn.jxufe.homework.servlet.QueryServlet</servlet-class>
</servlet>
<filter>
<filter-name>MyFilter</filter-name>
<filter-class>cn.jxufe.homework.filter.MyFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>MyFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<servlet-mapping>
<servlet-name>UserLoginServlet</servlet-name>
<url-pattern>/userlogin</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>UpdateServlet</servlet-name>
<url-pattern>/update</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>QueryServlet</servlet-name>
<url-pattern>/query</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
</welcome-file-list>
</web-app>
然後是login.jsp:
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" contentType="text/html;charset=utf-8">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'login.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<style>
table{
width:400px;
height: auto;
margin: 200 auto;
}
h1{
letter-spacing:20px;
width: 200px;
height: auto;
margin: 150px auto;
}
</style>
</head>
<body>
<form action="/homework/userlogin" method="post">
<h1>登錄</h1>
<table>
<tr><td><label for="admin">賬號:</label></td>
<td><input type="text" placeholder="請輸入賬號" id="admin" name="admin"></td></tr>
<tr><td><label for="password">密碼:</label></td>
<td><input type="password" name="password" id="password"></td></tr>
<tr><td><label for="authority">用戶權限:</label></td>
<td><input type="radio" name="authority" value="normal" id="normal"><label for="normal">普通</label>
<input type="radio" name="authority" value="super" id="super"><label for="super">超級</label></td></tr>
<tr><td><input type="submit" value=" 登錄 "></td><td><input type="reset" value="清空內容"></td></tr>
</table>
</form>
</body>
</html>
界面如圖:
然後是過濾器代碼:
package cn.jxufe.homework.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.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import cn.jxufe.homework.model.User;
public class MyFilter implements Filter {
@Override
public void destroy() {
// TODO Auto-generated method stub
System.out.println("MyFilter.class.destroy()");
}
@Override
public void doFilter(ServletRequest arg0, ServletResponse arg1,
FilterChain arg2) throws IOException, ServletException {
System.out.println("MyFilter.class.doFilter()");
HttpServletRequest request = (HttpServletRequest) arg0;
HttpServletResponse response = (HttpServletResponse) arg1;
String uri = request.getRequestURI();
if(uri.contains("login.jsp") || uri.contains("userlogin")){
arg2.doFilter(arg0, arg1);
System.out.println("uri.contains(\"login.jsp\") || uri.contains(\"userlogin\")");
return;
}
HttpSession session = request.getSession();
User user = (User)session.getAttribute("user");
if(user == null){
response.sendRedirect("login.jsp");
}else{
arg2.doFilter(arg0, arg1);
}
}
@Override
public void init(FilterConfig arg0) throws ServletException {
System.out.println("MyFilter.class.init()");
}
}
UserLoginServlet代碼:
package cn.jxufe.homework.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import cn.jxufe.homework.model.User;
import cn.jxufe.homework.service.GetRight;
public class UserLoginServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
System.out.println("UserLoginServlet.class");
String admin = request.getParameter("admin");
String password = request.getParameter("password");
String authority = request.getParameter("authority");
boolean infoIsRight = GetRight.isRight(authority, admin, password);
System.out.println("is info right " + infoIsRight);
if(infoIsRight){
User user = new User(admin, password, authority);
request.getSession().setAttribute("user", user);
response.sendRedirect("index.jsp");
}else
response.sendRedirect("login.jsp");
}
}
User類:還有setter和getter和構造函數不放上來了!
當我們直接執行UpdateServlet時就會直接跳轉至login.jsp。
並且控制檯顯示
web.xml中將filter的url-pattern設置爲/*,這表示給過濾器過濾的是這個web項目下的每一個程序。
所以我們訪問UpdateServlet時,先執行過濾器中的doFilter()函數
因爲其request的uri不符合uri.contains("login.jsp") || uri.contains("userlogin")而且也沒有添加過session(可以看下這兩個很好的講解:淺談Session與Cookie的區別與聯繫 和 Http Session和Cookie)。
所以就只直接跳轉至登錄界面!而訪問登錄界面,又得過濾一次,這時候就滿足:
所以就有了後兩句。
現在我們登錄試試,輸入賬號:zhangsan 密碼:123456 選擇超級用戶單選框,然後在界面就能看到這個:。
控制檯內容:
MyFilter.class.doFilter()
uri.contains("login.jsp") || uri.contains("userlogin")
UserLoginServlet.class
GetRight.class
MyFilter.class.doFilter()
流程就是login提交表單後,myfilter過濾,然後再通過,到UserLoginServlet,通過GetRight類驗證賬號密碼是否正確,如果正確返回true,回到UserLoginServlet,servlet將request中的賬號密碼權限信息封裝成一個User對象,添加進session中,然後再跳轉至index.jsp,這之前還要過一次過濾器!
整個文件這裏下載 密碼:bdyk
以上。