第六次

1.安装MySQL数据库，建立用户表 uid uname upwd 并插入3条数据

2.制作jsp登录页面 login.jsp 提交到dologin.jsp，使用jdbc连数据库，判断输入的用户名密码是否存在

3.如果存在，把用户名保存在SESSION中，跳转到welcome.jsp，welcome.jsp中读取session中的用户名，显示欢迎你xxx

4.若不存在，跳到登录页面。


package com.zhangjun.lty;

import java.sql.DriverManager;

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

import com.mysql.jdbc.Driver;

public class JDBCKu {

    public static Connection getConnection() throws Exception {
        //1.获取Driver实现类的对象
        Class clazz = Class.forName("com.mysql.jdbc.Driver");
        Driver driver = (Driver) clazz.newInstance();

        //2.提供另外三个连接的基本信息
        String url = "jdbc:mysql://localhost:3306/user_info?useUnicode=true&characterEncoding=utf8";
        String user="root";
        String password = "root";

        //注册驱动
        DriverManager.registerDriver(driver);

        //获取连接
        Connection conn = DriverManager.getConnection(url,user,password);
        return conn;
    }

    // 关闭连接
    public static void closeAll(Connection conn, PreparedStatement ps, ResultSet rs) throws Exception {
        if (rs != null)
            rs.close();
        if (ps != null)
            ps.close();
        if (conn != null)
            conn.close();
    }

}

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
    <title>$Title$</title>
  </head>

  <body>
  <form action="doLogin.jsp" method="post" >
    用户名:<input type="text" name="username"/>
    <br>
    密码:<input type="password"  name="password"/>
    <br>
    <input type="submit" value="登录">
  </form>
  </body>
</html>

<%@ page import="java.sql.Connection" %>
<%@ page import="static com.school.lty.JDBCKu.getConnection" %>
<%@ page import="java.sql.PreparedStatement" %>
<%@ page import="java.sql.ResultSet" %>
<%@ page import="com.school.lty.BaseDao" %>
<%@ page import="com.school.lty.JDBCKu" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>

<%
    JDBCKu jdbcKu = new JDBCKu();
    String username = request.getParameter("username");
    String password = request.getParameter("password");

    Connection conn = jdbcKu.getConnection();
    String sql = "select * from user where uname = ? and upassword = ?";
    PreparedStatement ps = conn.prepareStatement(sql);
    ps.setNString(1,username);
    ps.setNString(2,password);

    ResultSet rs = ps.executeQuery();

    if (rs.next() == true) {
        request.getSession().setAttribute("username",username);
        request.getRequestDispatcher("welcome.jsp").forward(request,response);
    }else{
        response.sendRedirect("index.jsp");
    }

    jdbcKu.closeAll(conn, ps, rs);
%>
<body>

</body>
</html>

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>

<%
    String username = (String) request.getSession().getAttribute("username");
%>
欢迎你!!!<%=username%>
</body>
</html>