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Java代码登录拦截器例子
通常我们在点击某个按钮的时候，对某个对象进行操作，是需要登陆才能做的，这时候就需要一个拦截器对某个方法进行拦截，
比如你在一个图书管理中心中你要借书，这时候你就会被要求出示借书证，管理员才能借书给你。而拦截器就具有这样的功能
：游客点击借书按钮-->后台拦截器拦截该方法-->判断你是否登陆-->已经登陆-->允许操作-->没登陆-->请登陆-->允许操作
代码如下：
UserFiler.java
package com.utis.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;public class UserFiter implements Filter{ public void init(FilterConfig filterConfig) throws ServletException { // TODO Auto-generated method stub } public void destroy() { // TODO Auto-generated method stub } public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { //获取HttpSession对象，判断是否登陆 HttpServletRequest req = (HttpServletRequest) request; HttpServletResponse res = (HttpServletResponse) response; HttpSession session = req.getSession(); if(session.getAttribute("model")==null){ //非法访问，没有登陆，跳转到登陆页面 session.setAttribute("error", "非法访问"); // 保存客户想要去的地址, 登录成功后则直接跳转,而不是到首页 String goURL = req.getServletPath();//(获取到地址不包括参数) //判断参数是否为空，不null就获取参数 if(req.getQueryString()!=null){ goURL+="?"+req.getQueryString(); } session.setAttribute("goURL", goURL); res.sendRedirect(req.getContextPath() + "/user/userLogin.jsp"); }else{ // 如果有下一个过滤器则跳转到下一个过滤器否则目标页面 chain.doFilter(request, response); } }}web.xml
<filter>
<!-- 配置在web.xml的拦截器，在容器启动的时候一起启动 --> <filter-name>userFilter</filter-name> <filter-class>com.utis.filter.UserFiter</filter-class> </filter> <filter-mapping> <filter-name>userFilter</filter-name> <url-pattern>/book/*</url-pattern> </filter-mapping>
UserContrller.java
/** * 用户登陆功能 * @return */ @RequestMapping(value="http://www.mamicode.com/login",method=RequestMethod.POST) public ModelAndView userLogin(@Valid User user,HttpServletRequest request,HttpServletResponse response){ Map<String, Object> maplist = new HashMap<String, Object>(); HttpSession session = request.getSession(); User model = userService.findUser(user); if(model != null && !model.equals("")){ session.setAttribute("model", model); maplist.put("model", model); return new ModelAndView("index","maplist",maplist); }else{ request.setAttribute("message", "用户或密码错误!"); return new ModelAndView("user/userLogin"); } }userLogin.jsp
<html> <head> <title>登陆页面</title> </head> <body> <center> <h1>登陆页面</h1> <table> <form action="login" method="post"> 用户名:<input type="text" class="username" name="username"/><br/> 密 码:<input type="password" class="password" name="password"/><br/> <input type="submit" value="http://www.mamicode.com/登陆"><br/> </form> ${message} </table> </center> </body></html>index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%><% String path = request.getContextPath(); String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort() + path + "/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> <base href="http://www.mamicode.com/"> <title>首页</title> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="This is my page"> <!-- <link rel="stylesheet" type="text/css" href="http://www.mamicode.com/styles.css"> --> </head> <body> <CENTER> <h1>图书首页</h1> <c:choose> <c:when test="${empty sessionScope.model}"> <a href="http://www.mamicode.com/user/userLogin.jsp">登陆</a> <a href="http://www.mamicode.com/user/userRegister.jsp">注册</a> </c:when> <c:otherwise> 欢迎使用图书管理系统：${sessionScope.model.username } </c:otherwise> </c:choose> <c:if test="${booklist ne ‘‘ && booklist != null}"> <!-- 作为隐藏的传递参数 --> <table border="1" style="border-collapse: collapse; border-color: blue;"> <!-- 表头 --> <tr> <th> 书名 </th> <th> 出版社 </th> <th> 是否可借 </th> <th> 数量 </th> <th> 操作 </th> </tr> <!-- 显示数据列表 --> <c:forEach items="${booklist}" var="book"> <tr> <td> ${book.bookname } </td> <td> ${book.chubanshe } </td> <td> ${book.state } </td> <td> ${book.number } </td> <td> <a href="http://www.mamicode.com/book/borrowBook?bookid=${book.bookid }&userid=${sessionScope.model.userid }">借书</a> </td> </tr> </c:forEach> <!-- 其他操作 --> <tr> <td colspan="7"> <a href="http://www.mamicode.com/#">添加</a> </td> </tr> </table> </c:if> </CENTER> </body></html>初始化数据
IniDataListener.java
package com.booksys.listener;import java.util.Timer;import javax.servlet.ServletContextEvent;import javax.servlet.ServletContextListener;import org.springframework.context.ApplicationContext;import org.springframework.web.context.support.WebApplicationContextUtils;import com.booksys.service.BookService;import com.utis.util.GoodsTimerTask;/** * 该类的主要作用是用于加载index首页的方法，查询数据，显示首页 * @author chunyu * */public class InitDataListener implements ServletContextListener{ private BookService bookService; private GoodsTimerTask goodsTimerTask; public void contextDestroyed(ServletContextEvent sce) { } public void contextInitialized(ServletContextEvent event) { ApplicationContext context = null; //通过spring的web工具类来加载spring容器(配置文件)，并且调用某个类来做某事 context=WebApplicationContextUtils.getWebApplicationContext(event.getServletContext()); //1、获取bookservice bookService = (BookService) context.getBean("bookService"); goodsTimerTask = (GoodsTimerTask) context.getBean("goodsTimerTask"); //2、查询所有图书 event.getServletContext().setAttribute("booklist", bookService.findBook()); //将Application内置对象，传入到goodsTimerTask查询的数据对象中 goodsTimerTask.setApplication(event.getServletContext()); // 设置时间任务,每隔一段时间加载首页的商品信息, 此线程必须设置守护线程, 主线程停止的时候此线程也要停止 new Timer(true).schedule(goodsTimerTask, 0,1000*60); }}web.xml
<!-- 初始化首页信息（查询）监听器 --> <listener> <listener-class> com.booksys.listener.InitDataListener </listener-class> </listener>
时间戳：用于自动调用查询方法，更新首页数据显示
GoodsTimerTask.java
package com.utis.util;import java.util.List;import java.util.TimerTask;import javax.annotation.Resource;import javax.servlet.ServletContext;import org.springframework.stereotype.Component;import com.booksys.domain.Book;import com.booksys.service.BookService;@Component("goodsTimerTask")public class GoodsTimerTask extends TimerTask { //传入Application内置对象 private ServletContext application; public void setApplication(ServletContext application) { this.application = application; } //获取业务逻辑类 @Resource private BookService bookService=null; @Override public void run() { System.out.println("GoodsTimerTask.run()"); //首页加载图书数据信息 List<Book> booklist = bookService.findBook(); //将list集合数据存储到app内置对象中，在inde前台通过循环查询出来 application.setAttribute("booklist", booklist); }}
Java代码登录拦截器例子
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