JDBCUtils附加增删改查功能

driver = com.mysql.jdbc.Driver
url = jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=UTF-8
user = root
password = 123456

package cn.pzhu.util;

import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.*;

public class JDBCUtils {
    private static String driver = null;
    private static String url = null;
    private static String user = null;
    private static String password = null;
    private Connection con;
    private PreparedStatement preparedStatement;
    private ResultSet resultSet;
    //1.注册驱动
    static{
        InputStream in = JDBCUtil.class.getClassLoader().getResourceAsStream("db.properties");
        Properties properties = new Properties();
        try {
            properties.load(in);
            driver = properties.getProperty("driver");
            url = properties.getProperty("url");
            user = properties.getProperty("user");
            password = properties.getProperty("password");
            try {
                Class.forName(driver);
            } catch (ClassNotFoundException e) {
                e.printStackTrace();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
   public JDBCUtils(){
       try {
           con=DriverManager.getConnection(url, user, password);
       } catch (SQLException e) {
           e.printStackTrace();
       }
   }
    //2.获得连接
    public  Connection getConnection(){
        return con;
    }

    //3.释放资源
    public static void close(Connection connection, Statement statement, ResultSet result){
        if(result!=null){
            try {
                result.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
        if(connection!=null){
            try {
                connection.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }           if(statement!=null){
            try {
                statement.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
    }

    
    public boolean updateSql(String sql, List