JDBC连接MySQL并实现模糊查询

package com.zdx.JDBC;
 
import java.sql.*;
 
public class JAVA1129_5 {
    public static void main(String[] args) {
        //设置空对象，注册驱动，获取连接，创建操作，处理结果集，释放资源
        String url = "jdbc:mysql://127.0.0.1:3306/hello";
        String username = "root";
        String password = "rota";
 
        String SQL = "insert into stu values(1,'zdx','nbnc'),(2,'cyc','qwq');";
//        String SQL1 = "update stu set sname ='xzq',major='bask' where sno = '1';";
        String SQL1="select * from stu";
        Connection connection = null;
        Statement statement = null;
        ResultSet resultset = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            connection = DriverManager.getConnection(url, username, password);
            statement = connection.createStatement();
            int cnt = statement.executeUpdate(SQL);
            if (cnt != 0) {
                System.out.println("执行成功");
            }
            ResultSet result = statement.executeQuery(SQL1);
            while (result.next()) {
                //随着光标移动对操作对象进行操作
                System.out.println("nbnb");
            }
 
        } catch (SQLException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
 
        //释放资源，必须在最后加上finally语句块执行
        finally {
                if (resultset != null) {
                    try {
                        resultset.close();
                    } catch (SQLException throwables) {
                        throwables.printStackTrace();
                    }
                }
                if (statement != null) {
                    try {
                        statement.close();
                    } catch (SQLException throwables) {
                        throwables.printStackTrace();
                    }
                }
                if (connection != null) {
                    try {
                        connection.close();
                    } catch (SQLException throwables) {
                        throwables.printStackTrace();
                    }
                }
            }
        }
    }
 
 

package com.zdx.JDBC;
 
import java.sql.*;
 
//2021.11.2920点03分 对数据库的工具类进行封装
public class  DBUtil{
    private DBUtil(){}
    static{
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }//利用静态代码块在类加载时只加载一次的特性注册驱动。
 
    //获取连接的方法
    public static Connection getConnection (String url,String user,String password)throws SQLException{
       return   DriverManager.getConnection(url,user,password);//这里注意驱动管理类内调用的获取连接方法返回对象就是connection对象。
    }
 
    //关闭资源
    //按照顺序，结果集，数据库操作对象，连接对象！
    public static void close(Connection connection,Statement ps,ResultSet resultSet){
 
        if(resultSet!=null){
            try {
                resultSet.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
 
        if(ps!=null){
            try {
                ps.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
 
        if(connection!=null){
            try {
                connection.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
    }
 
}

package com.zdx.JDBC;
 
import java.sql.*;
 
public class Main {
 
    public static void main(String[] args) {
 
        Connection connection = null;
        PreparedStatement ps = null;
        ResultSet resultSet = null;
        String url = "jdbc:mysql://127.0.0.1:3306/hello";
        String user = "root";
        String password = "rota";
        //获取连接
        try {
            connection = DBUtil.getConnection(url, user, password);
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }
        //获取预编译的数据库操作对象
        String SQL = "select sname from stu where sname like ?";
        try {
            ps = connection.prepareStatement(SQL);
            ps.setString(1, "_y%");
            resultSet = ps.executeQuery();
            while (resultSet.next()) {
                System.out.println(resultSet.getString("sname"));
            }
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }
 
 
        //释放资源
        finally {
            DBUtil.close(connection, ps, resultSet);
        }
    }
}