提取工具类来插入删除查询

Statement对象

代码实现

1.提取工具类

• 建一个properties文件

driver=com.mysql.jdbc.Driver
url = jdbc:mysql://localhost:3306/jdbcstudy?useUnicode=true&characterEncoding=utf8&useSSL=false
username=root
password=123456

• 读取工具类

package com.shushu.lesson.utils;
​
import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;
​
public class JDBCUtils {
​
    private static String driver = null;
    private static String url = null;
    private static String username = null;
    private static String password = null;
​
​
    static{
​
        try {
            InputStream in = JDBCUtils.class.getClassLoader().getResourceAsStream("db.properties");
            Properties properties = new Properties();
            properties.load(in);
            driver = properties.getProperty("driver");
            url = properties.getProperty("url");
            username = properties.getProperty("username");
            password = properties.getProperty("password");
​
            //1.驱动只用加载一次
            Class.forName(driver);
​
        } catch (IOException | ClassNotFoundException e) {
            e.printStackTrace();
        }
    }
​
    //获取连接
    public static Connection getConnection() throws SQLException {
        Connection connection = DriverManager.getConnection(url,username,password);
        return connection;
    }
    //释放连接资源
    public static void release(Connection conn, Statement st, ResultSet rs) throws SQLException {
        if (rs!=null)
            rs.close();
        if (st!=null)
            st.close();
        if (conn!=null)
            conn.close();
    }
}
​

 

 

插入

//插入
package com.shushu.lesson;
​
import com.shushu.lesson.utils.JDBCUtils;
​
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
​
public class TestInsert {
    public static void main(String[] args) throws SQLException {
        Connection conn = null;
        Statement st= null;
        ResultSet rs = null;
        conn = JDBCUtils.getConnection();//获得数据库连接
        st = conn.createStatement();//获取SQL的执行对象
        String sql = "INSERT INTO users(id,`name`,`password`,`email`,`birthday`)" +
                "VALUES(4,'shushu','123456','244@QQQ.COM','2020-01-01')";
        int i = st.executeUpdate(sql);
        if (i>0)
            System.out.println("插入成功");
        JDBCUtils.release(conn,st,rs);
    }
}
​

删除

package com.shushu.lesson;
​
import com.shushu.lesson.utils.JDBCUtils;
​
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
​
public class TestDelete {
    public static void main(String[] args) throws SQLException {
        Connection conn = null;
        Statement st = null;
        ResultSet rs = null;
        conn = JDBCUtils.getConnection();
        st = conn.createStatement();
        String sql = "DELETE FROM users WHERE id = 4";
        int i = st.executeUpdate(sql);
        if (i>0)
            System.out.println("删除成功");
        JDBCUtils.release(conn,st,rs);
    }
}
​

查询

package com.shushu.lesson;
​
import com.shushu.lesson.utils.JDBCUtils;
​
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
​
public class TestQuery {
    public static void main(String[] args) throws SQLException {
        Connection conn = null;
        Statement st = null;
        ResultSet rs = null;
        conn = JDBCUtils.getConnection();
        st = conn.createStatement();
        String sql = "SELECT * FROM users WHERE id = 4";
        rs = st.executeQuery(sql);
        while (rs.next()){
            System.out.println(rs.getString("name"));
        }
        JDBCUtils.release(conn,st,rs);
    }
}
​