需求:
1.通过键盘录入用户名密码
2.判断用户是否封路成功(查表)
步骤:
1.创建数据库表
CREATE TABLE USER(
id INT PRIMARY KEY AUTO_INCREMENT,
username VARCHAR(32),
PASSWORD VARCHAR(32)
);
SELECT *FROM USER;
INSERT INTO USER VALUES(NULL,'zhangsan','123');
INSERT INTO USER VALUES(NULL,'lisi','234')
2.编码
//需求: // // 1.通过键盘录入用户名密码 // // 2.判断用户是否封路成功(查表) package cn.itcast.jdbc; import java.sql.*; import java.util.Scanner; public class jdbc { public static void main(String[] args) { //1.键盘录入 Scanner sc = new Scanner(System.in); System.out.println("请输入用户名:"); String username=sc.nextLine(); System.out.println("请输入密码:"); String password=sc.nextLine(); boolean flag=new jdbc().login2(username,password); if(flag){ System.out.println("登陆成功"); }else { System.out.println("用户名密码不正确"); } //2.调用方法 } //登录方法(需要返回值) public boolean login(String username,String password){ if(username ==null || password ==null){ System.out.println("用户名或者密码为空!!!"); return false; } Connection conn=null; Statement stmt=null; ResultSet rs =null; //1.获取数据库连接 try { conn =JDBCUtils.getConnection(); //定义sql String sql = "select * from user where username='" +username+ " ' and password='"+password+"'"; //获取对象 stmt=conn.createStatement(); //执行查询 rs=stmt.executeQuery(sql); //判断 // if(rs.next()){ // return true; // }else{ // return false; // } return rs.next(); } catch (SQLException throwables) { throwables.printStackTrace(); }finally { JDBCUtils.close(rs,stmt,conn); } return false; } public boolean login2(String username,String password){ if(username ==null || password ==null){ System.out.println("用户名或者密码为空!!!"); return false; } Connection conn=null; PreparedStatement pstmt=null; ResultSet rs =null; //1.获取数据库连接 try { conn =JDBCUtils.getConnection(); //定义sql String sql = "select * from user where username=? and password=?"; //获取对象 pstmt=conn.prepareStatement(sql); //执行查询 pstmt.setString(1,username); pstmt.setString(2,password); rs=pstmt.executeQuery(); //判断 // if(rs.next()){ // return true; // }else{ // return false; // } return rs.next(); } catch (SQLException throwables) { throwables.printStackTrace(); }finally { JDBCUtils.close(rs,pstmt,conn); } return false; } }