通常我們在點擊某個按鈕的時候，對某個對象進行操作，是需要登陸才能做的，這時候就需要一個攔截器對某個方法進行攔截，
比如你在一個圖書管理中心中你要借書，這時候你就會被要求出示借書證，管理員才能借書給你。而攔截器就具有這樣的功能
：游客點擊借書按鈕-->后台攔截器攔截該方法-->判斷你是否登陸-->已經登陸-->允許操作-->沒登陸-->請登陸-->允許操作
代碼如下：
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 {
//獲取HttpSession對象，判斷是否登陸
HttpServletRequest req = (HttpServletRequest) request;
HttpServletResponse res = (HttpServletResponse) response;
HttpSession session = req.getSession();
if(session.getAttribute("model")==null){
//非法訪問，沒有登陸，跳轉到登陸頁面
session.setAttribute("error", "非法訪問");
// 保存客戶想要去的地址, 登錄成功后則直接跳轉,而不是到首頁
String goURL = req.getServletPath();//(獲取到地址不包括參數)
//判斷參數是否為空，不null就獲取參數
if(req.getQueryString()!=null){
goURL+="?"+req.getQueryString();
}
session.setAttribute("goURL", goURL);
res.sendRedirect(req.getContextPath() + "/user/userLogin.jsp");
}else{
// 如果有下一個過濾器則跳轉到下一個過濾器否則目標頁面
chain.doFilter(request, response);
}
}
}
web.xml
<filter>
<!-- 配置在web.xml的攔截器，在容器啟動的時候一起啟動 --> <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
/**
* 用戶登陸功能
* @return
*/
@RequestMapping(value="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", "用戶或密碼錯誤!");
return new ModelAndView("user/userLogin");
}
}
userLogin.jsp
<html>
<head>
<title>登陸頁面</title>
</head>
<body>
<center>
<h1>登陸頁面</h1>
<table>
<form action="login" method="post">
用戶名:<input type="text" class="username" name="username"/><br/>
密 碼:<input type="password" class="password" name="password"/><br/>
<input type="submit" value="登陸"><br/>
</form>
${message}
</table>
</center>
</body>
</html>
index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme() + "://"
+ request.getServerName() + ":" + request.getServerPort()
+ path + "/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>首頁</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<CENTER>
<h1>圖書首頁</h1>
<c:choose>
<c:when test="${empty sessionScope.model}">
<a href="<%=basePath%>user/userLogin.jsp">登陸</a>
<a href="<%=basePath%>user/userRegister.jsp">注冊</a>
</c:when>
<c:otherwise>
歡迎使用圖書管理系統：${sessionScope.model.username }
</c:otherwise>
</c:choose>
<c:if test="${booklist ne '' && booklist != null}">
<!-- 作為隱藏的傳遞參數 -->
<table border="1"
style="border-collapse: collapse; border-color: blue;">
<!-- 表頭 -->
<tr>
<th>
書名
</th>
<th>
出版社
</th>
<th>
是否可借
</th>
<th>
數量
</th>
<th>
操作
</th>
</tr>
<!-- 顯示數據列表 -->
<c:forEach items="${booklist}" var="book">
<tr>
<td>
${book.bookname }
</td>
<td>
${book.chubanshe }
</td>
<td>
${book.state }
</td>
<td>
${book.number }
</td>
<td>
<a
href="book/borrowBook?bookid=${book.bookid }&userid=${sessionScope.model.userid }">借書</a>
</td>
</tr>
</c:forEach>
<!-- 其他操作 -->
<tr>
<td colspan="7">
<a href="#">添加</a>
</td>
</tr>
</table>
</c:if>
</CENTER>
</body>
</html>
初始化數據
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;
/**
* 該類的主要作用是用於加載index首頁的方法，查詢數據，顯示首頁
* @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;
//通過spring的web工具類來加載spring容器(配置文件)，並且調用某個類來做某事
context=WebApplicationContextUtils.getWebApplicationContext(event.getServletContext());
//1、獲取bookservice
bookService = (BookService) context.getBean("bookService");
goodsTimerTask = (GoodsTimerTask) context.getBean("goodsTimerTask");
//2、查詢所有圖書
event.getServletContext().setAttribute("booklist", bookService.findBook());
//將Application內置對象，傳入到goodsTimerTask查詢的數據對象中
goodsTimerTask.setApplication(event.getServletContext());
// 設置時間任務,每隔一段時間加載首頁的商品信息, 此線程必須設置守護線程, 主線程停止的時候此線程也要停止
new Timer(true).schedule(goodsTimerTask, 0,1000*60);
}
}
web.xml
<!-- 初始化首頁信息（查詢）監聽器 --> <listener> <listener-class> com.booksys.listener.InitDataListener </listener-class> </listener>
時間戳：用於自動調用查詢方法，更新首頁數據顯示
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 {
//傳入Application內置對象
private ServletContext application;
public void setApplication(ServletContext application) {
this.application = application;
}
//獲取業務邏輯類
@Resource
private BookService bookService=null;
@Override
public void run() {
System.out.println("GoodsTimerTask.run()");
//首頁加載圖書數據信息
List<Book> booklist = bookService.findBook();
//將list集合數據存儲到app內置對象中，在inde前台通過循環查詢出來
application.setAttribute("booklist", booklist);
}
}