封装工具类Utils

db.properties

driver = com.mysql.jdbc.Driver
url = jdbc:mysql://localhost:3306/jdbcstudy?useUnicode=true&characterEncoding=utf-8
username = root
password = 1234

Utils

package com.zhaoyang.utils;

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.加载驱动
            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
    public static void release(Connection connection, 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 (connection!=null) {
            try {
                connection.close ();
            } catch (SQLException throwables) {
                throwables.printStackTrace ();
            }
        }
    }

}