servlet+jsp用户登录实现

项目结构如下：

登录界面

登录成功

登录失败

user代码段

package bean;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import util.DB;
public class user {
    private String username;
    private String password;
    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;
    }
    public boolean Check(String username,String password)throws Exception{
        Connection conn=null;
        ResultSet rest=null;
        PreparedStatement prst=null;
        String sql="select * from user where username=?";
        boolean flag=false;
        try{
            conn=DB.getConn();
            prst=conn.prepareStatement(sql);
            prst.setString(1, username);
            rest=prst.executeQuery();
            if(rest.next()){
                if(password.equals(rest.getString("password"))){
                    flag=true;
                }else{
                    throw new Exception("密码不对哦");
                }
            }else{
                throw new Exception("用户名不存在");
            }
        }catch(Exception e){
            e.printStackTrace();
        }finally{
            try {
                rest.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            try {
                prst.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            try {
                conn.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        return flag;
    }
}

DB代码段

package util;
import java.sql.Connection;
import java.sql.DriverManager;
public class DB {
    public static Connection getConn(){
        Connection conn=null;
        try{
            String url="jdbc:mysql://localhost/student";
            String user="root";
            String password="root";
            Class.forName("com.mysql.jdbc.Driver");
            conn=DriverManager.getConnection(url, user, password);
            if(conn!=null){
                System.out.println("数据库连接成功！");
            }
        }catch(Exception e){
            e.printStackTrace();
        }
        return conn;
    }
}

userServlet代码段

package servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import bean.user;
/**
 * Servlet implementation class userServlet
 */
@WebServlet(
        urlPatterns={"/userServlet"},name="userServlet" 
        )
public class userServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
    /**
     * @see HttpServlet#HttpServlet()
     */
    public userServlet() {
        super();
        // TODO Auto-generated constructor stub
    }
    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doPost(request,response);
    }
    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        request.setCharacterEncoding("utf-8");//处理表单中文乱码
        user u=new user();
        String username,password;
        try{
            username=request.getParameter("username");
            password=request.getParameter("password");
            if(u.Check(username, password)){
                u.setUsername(username);
                u.setPassword(password);
                request.getSession().setAttribute("use", u);
                request.getRequestDispatcher("/Success.jsp").forward(request, response);
            }else{
                request.getRequestDispatcher("/fail.jsp").forward(request, response);
            }
        }catch(Exception e){
            e.printStackTrace();
        }
    }
}

login.jsp代码段

<%@ 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">
<html>
  <head>
    <base href="<%=basePath%>">
    <title>用户登录</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>
        <form action="<%=request.getContextPath() %>/userServlet" method="post">
            <table>
                <tr>
                    <td>用户名:</td>
                    <td><input type="text" name="username"></td>
                </tr>
                <tr>
                    <td>密码:</td>
                    <td><input type="password" name="password"></td>
                </tr>
                <tr>
                    <td></td>
                    <td><input type="submit" value="登录"></td>
                </tr>
            </table>
        </form>
    </center>
  </body>
</html>

success.jsp代码段

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<jsp:useBean id="use" class="bean.user" scope="session"></jsp:useBean>
<%
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>登录成功</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>
    <table>
                <tr>
                    <td>用户名:</td>
                    <td><jsp:getProperty name="use" property="username"/></td>
                </tr>
                <tr>
                    <td>密码:</td>
                    <td><jsp:getProperty name="use" property="password"/></td>
                </tr>
            </table>
  </body>
</html>

fail.jsp代码段

<%@ 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">
<html>
  <head>
    <base href="<%=basePath%>">
    <title>登录失败</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>
        登录失败!<a href="login.jsp">返回登录</a>
  </body>
</html>