JDBC-API详解-PreparedStatement-SQL注入演示

 

 

 

package Test;

import org.junit.Test;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

public class JDBCdemo5_UserLogin {
    /*
    *演示用户登录
    * */
    @Test
    public void testUserLogin() throws Exception {
        //1.注册驱动
        //Class.forName("com.mysql.jdbc.Driver");
        //2.获取连接
        String url = "jdbc:mysql:///test?useSSL=false";
        String username = "root";
        String password = "1234";
        Connection conn = DriverManager.getConnection(url, username, password);

        //接收用户输入用户名和密码
        String name="zhangsan";
        String pwd="123";

        String Sql=" select * from tb_user where username='"+name+"' and password='"+pwd+"' ";

        //获取stmt对象
        Statement stmt = conn.createStatement();

        //执行sql
        ResultSet rs = stmt.executeQuery(Sql);

        //判断登录是否成功
        if (rs.next()){
            System.out.println("登录成功");
        }else {
            System.out.println("登录失败");
        }

        //7.释放资源
        rs.close();
        stmt.close();
        conn.close();
    }
    /*
     *演示sql注入
     * ' or '1' = '1
     *
     * select * from tb_user where username='dawdsan' and password='' or '1' = '1'
     * 通过输入的语句来修改事先定义好的sql语句本身的意义
     * */
    @Test
    public void testlogin_Inject() throws Exception {
        //1.注册驱动
        //Class.forName("com.mysql.jdbc.Driver");
        //2.获取连接
        String url = "jdbc:mysql:///test?useSSL=false";
        String username = "root";
        String password = "1234";
        Connection conn = DriverManager.getConnection(url, username, password);

        //接收用户输入用户名和密码
        String name="dawdsan";
        String pwd="' or '1' = '1";

        String Sql=" select * from tb_user where username='"+name+"' and password='"+pwd+"' ";
        System.out.println(Sql);

        //获取stmt对象
        Statement stmt = conn.createStatement();

        //执行sql
        ResultSet rs = stmt.executeQuery(Sql);

        //判断登录是否成功
        if (rs.next()){
            System.out.println("登录成功");
        }else {
            System.out.println("登录失败");
        }

        //7.释放资源
        rs.close();
        stmt.close();
        conn.close();
    }

}