Java数据库

package com.wang.lesson02.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;
    //静态代码块来实现加载mysql驱动
    static {
        try{
            //db.properties里的信息被读取出来了
            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");

            //驱动只用加载一次
            Class.forName(driver);

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    //获取连接
    public static Connection getConnection() throws SQLException {
            return DriverManager.getConnection(url,username,password);
    }


    //释放连接资源
    public static void release(Connection con, Statement st, ResultSet rs){
        if (rs!=null){
            try {
                rs.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }

        if(st!=null){
            try {
                st.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }

        if(con!=null){
            try {
                con.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
    }


}

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