JDBC连接数据库工具类

package org.util;
import java.sql.*;
public class BaseDao {
    //驱动
   private static String driver = "com.mysql.jdbc.Driver";
   private static String url = "jdbc:mysql://127.0.0.1:3306/mytest?characterEncoding=utf-8&serverTimezone=Asia/Shanghai";
    //用户名
    private static String username = "root";
    //密码
    private static String pwd = "123456";
    /**
     * 创建连接
     * @return
     */
    public static Connection getConnection(){
        Connection connection=null;
        //加载驱动
        try {
            Class.forName(driver);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        //建立连接获取Connection对象
        try {
            connection= DriverManager.getConnection(url,username,pwd);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return connection;
    }
    /**
     * 关闭链接
     * @param connection
     * @param statement
     * @param resultSet
     */
    public static void closeAll(Connection connection, Statement statement, ResultSet resultSet){
        try {
            if(resultSet!=null){
                resultSet.close();
            }
            if(statement!=null){
                statement.close();
            }
            if (connection!=null){
                connection.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    /**
     * 执行增、删、改的方法
     * @param sql
     * @return
     */
    public static int execute(String sql){
        //获取链接
        Connection connection=getConnection();
        int flag=0;
        try {
            //创建Statement对象
            Statement statement=connection.createStatement();
            //执行sql语句
            flag=statement.executeUpdate(sql);
            //关闭链接
            closeAll(connection,statement,null);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return flag;
    }
    /*
      测试
     */
    public static void main(String[] args) {
        String sql = "SELECT * FROM bs_structure  WHERE id = 1688350472671";
        Connection connection = getConnection();
        Statement statement = null;
        try {
            statement= connection.createStatement();
            ResultSet resultSet = statement.executeQuery(sql);
            while(resultSet.next()){
                String typename = resultSet.getString(3);
                System.out.println("类别名称："+typename);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}