java dbhelper

import javax.naming.spi.DirStateFactory;
import java.lang.reflect.Field;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;

public   class DBHelper {
  //  private static final String DRIVER = "com.mysql.jdbc.Driver";
   // private static final String URL = "jdbc:mysql://101.12.102.10:3306/test";
    //private static final String USER = "root";
    //private static final String PASSWORD = "123456";

    private static final String DRIVER = "com.mysql.jdbc.Driver";
    private static final String URL = "jdbc:mysql://rm-2ze66k2qxc95j13nl.mysql.rds.aliyuncs.com:3306/longfor_mdm";
    private static final String USER = "wydb003_rw";
    private static final String PASSWORD = "vzXYZ5h3MiDntZDtuCFE";

    private static DBHelper ins;

    public static DBHelper ins() {
        if (ins == null) {
            ins = new DBHelper();
        }
        return ins;
    }


    /**
     * 连接数据库
     *
     * @return 链接数据库对象
     */
    public Connection getConnection() {
        Connection conn = null;
        try {
            Class.forName(DRIVER);
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        try {
            conn = DriverManager.getConnection(URL, USER, PASSWORD);
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return conn;
    }

    /**
     * 释放相应的资源
     *
     * @param rs
     * @param pstmt
     * @param conn
     */
    public void closeAll(ResultSet rs, PreparedStatement pstmt, Connection conn) {
        try {
            if (rs != null) {
                rs.close();
            }
            if (pstmt != null) {
                pstmt.close();
            }
            if (conn != null) {
                conn.close();
            }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    /**
     * 此方法可以完成增删改所有的操作
     *
     * @param sql
     * @param params
     * @return true or false
     */
    public boolean excuteUpdate(String sql, List