小峰servlet/jsp（3）登陆功能实现

一、User模型：

User.java:

 package com.java1234.model;

 public class User {

     private int id;
     private String userName;
     private String password;

     public User() {
         super();
         // TODO Auto-generated constructor stub
     }

     public User(String userName, String password) {
         super();
         this.userName = userName;
         this.password = password;
     }

     public int getId() {
         return id;
     }
     public void setId(int id) {
         this.id = id;
     }
     public String getUserName() {
         return userName;
     }
     public void setUserName(String userName) {
         this.userName = userName;
     }
     public String getPassword() {
         return password;
     }
     public void setPassword(String password) {
         this.password = password;
     }

 }

二、封装jdbc连接数据库：

 package com.java1234.util;

 import java.sql.Connection;
 import java.sql.DriverManager;

 public class DbUtil {

     private String dbUrl="jdbc:mysql://localhost:3306/db_jsp";
     private String dbUserName="root";
     private String dbPassword="123456";
     private String jdbcName="com.mysql.jdbc.Driver";

     public Connection getCon()throws Exception{
         Class.forName(jdbcName);
         Connection con=DriverManager.getConnection(dbUrl, dbUserName, dbPassword);
         return con;
     }

     public void closeCon(Connection con)throws Exception{
         if(con!=null){
             con.close();
         }
     }

     public static void main(String[] args) {
         DbUtil dbUtil=new DbUtil();
         try {
             dbUtil.getCon();
             System.out.println("连接成功");
         } catch (Exception e) {
             e.printStackTrace();
         }
     }
 }

三、userDao：

 package com.java1234.dao;

 import java.sql.Connection;
 import java.sql.PreparedStatement;
 import java.sql.ResultSet;

 import com.java1234.model.User;

 public class UserDao {

     public User login(Connection con,User user)throws Exception{
         User resultUser=null;
         String sql="select * from t_user where userName=? and password=?";
         PreparedStatement pstmt=con.prepareStatement(sql);
         pstmt.setString(1, user.getUserName());
         pstmt.setString(2, user.getPassword());
         ResultSet rs=pstmt.executeQuery();
         if(rs.next()){
             resultUser=new User();
             resultUser.setUserName(rs.getString("userName"));
             resultUser.setPassword(rs.getString("password"));
         }
         return resultUser;
     }

 }

四、loginServlet.java:

 package com.java1234.web;

 import java.io.IOException;
 import java.sql.Connection;

 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 com.java1234.dao.UserDao;
 import com.java1234.model.User;
 import com.java1234.util.DbUtil;

 public class LoginServlet extends HttpServlet{

     /**
      *
      */
     private static final long serialVersionUID = 1L;

     DbUtil dbUtil=new DbUtil();
     UserDao userDao=new UserDao();

     @Override
     protected void doGet(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {
         this.doPost(request, response);
     }

     @Override
     protected void doPost(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {
         String userName=request.getParameter("userName");
         String password=request.getParameter("password");

         Connection con=null;
         try {
             User user=new User(userName,password);
             con=dbUtil.getCon();
             User currentUser=userDao.login(con, user);
             if(currentUser==null){
                 request.setAttribute("error", "用户名或密码错误");
                 request.setAttribute("userName", userName);
                 request.setAttribute("password", password);
                 request.getRequestDispatcher("login.jsp").forward(request, response);
             }else{
                 HttpSession session=request.getSession();
                 session.setAttribute("currentUser", currentUser);
                 response.sendRedirect("main.jsp");
             }
         } catch (Exception e) {
             e.printStackTrace();
         }
     }

 }

前台登陆界面login.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="login" method="post">
 <table>
     <tr>
         <th colspan="2">用户登录</th>
     </tr>
     <tr>
         <td>用户名：</td>
         <td><input type="text" id="userName" name="userName" value="${userName }"/></td>
     </tr>
     <tr>
         <td>密码：</td>
         <td><input type="password" id="password" name="password" value="${password }"/></td>
     </tr>
     <tr>
         <td><input type="submit" value="登录"/></td>
         <td><font color="red">${error }</font></td>
     </tr>
 </table>
 </form>
 </body>
 </html>

登陆成功后跳转到main.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>
 主页！当前登录用户：${currentUser.userName } &nbsp;&nbsp;<a href="logout">注销</a>
 </body>
 </html>

五、注销方法：

LogoutServlet.java:

 package com.java1234.web;

 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;

 public class LogoutServlet extends HttpServlet{
     /**
      *
      */
     private static final long serialVersionUID = 1L;

     @Override
     protected void doGet(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {
         this.doPost(request, response);
     }

     @Override
     protected void doPost(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {
         request.getSession().invalidate();
         response.sendRedirect("login.jsp");
     }

 }

六、loginServlet.java/LogoutServlet.java两个servlet在web.xml中的配置：

web.xml配置：

 <?xml version="1.0" encoding="UTF-8"?>
 <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
   <display-name>HeadFirstJspServletChap05</display-name>
   <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>

   <servlet>
       <servlet-name>loginServlet</servlet-name>
       <servlet-class>com.java1234.web.LoginServlet</servlet-class>
   </servlet>

   <servlet-mapping>
       <servlet-name>loginServlet</servlet-name>
       <url-pattern>/login</url-pattern>
   </servlet-mapping>

   <servlet>
       <servlet-name>logoutServlet</servlet-name>
       <servlet-class>com.java1234.web.LogoutServlet</servlet-class>
   </servlet>

   <servlet-mapping>
       <servlet-name>logoutServlet</servlet-name>
       <url-pattern>/logout</url-pattern>
   </servlet-mapping>

   <filter>
       <filter-name>loginFilter</filter-name>
       <filter-class>com.java1234.filter.LoginFilter</filter-class>
   </filter>

   <filter-mapping>
       <filter-name>loginFilter</filter-name>
       <url-pattern>/*</url-pattern>
   </filter-mapping>

   <listener>
       <listener-class>
           com.java1234.listener.SessionAttributeListener
       </listener-class>
   </listener>
 </web-app>

七、Servlet过滤器：

过滤用户请求；

添加登陆过滤器，LoignFilter.java:

 package com.java1234.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.HttpSession;

 public class LoginFilter implements Filter{

     public void destroy() {

     }

     public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse,
             FilterChain filterChain) throws IOException, ServletException {
         HttpServletRequest request=(HttpServletRequest)servletRequest;
         HttpSession session=request.getSession();
         Object o=session.getAttribute("currentUser");
         String path=request.getServletPath();        //获取用户请求的路径 "/login"
         if(o==null&&path.indexOf("login")<0){
             request.getRequestDispatcher("login.jsp").forward(servletRequest, servletResponse);
         }else{
             filterChain.doFilter(servletRequest, servletResponse);
         }
     }

     public void init(FilterConfig arg0) throws ServletException {

     }

 }

八、Servlet监听器：

监听web事件，如application、session、request

 package com.java1234.listener;

 import javax.servlet.http.HttpSessionAttributeListener;
 import javax.servlet.http.HttpSessionBindingEvent;

 public class SessionAttributeListener implements HttpSessionAttributeListener{

     //session中添加attribute时候会监听到
     public void attributeAdded(HttpSessionBindingEvent httpSessionBindingEvent) {
         System.out.println("添加的属性名: "+httpSessionBindingEvent.getName()+",属性值："+httpSessionBindingEvent.getValue());
     }

     public void attributeRemoved(HttpSessionBindingEvent httpSessionBindingEvent) {
         System.out.println("删除的属性名: "+httpSessionBindingEvent.getName()+",属性值："+httpSessionBindingEvent.getValue());
     }

     public void attributeReplaced(HttpSessionBindingEvent httpSessionBindingEvent) {

     }

 }

配置listener见上面的web.xml;

登陆成功后，就能看到console打印：

servlet中跳转的两种方式：

response.sendRedirect("target.jsp");      　　　　//客户端跳转/重定向

request.getRequestDispatcher("target.jsp").forward(request, response);    //服务器端跳转/转发