android studio连接mysql 怎么老是异常

谁学逆向工程 2019-05-13 07:26:18

程序运行到
con = (com.mysql.jdbc.Connection)DriverManager.getConnection(url, user, password);
就老半天卡死，等好半天跳到第二个catch 语句。
即使 con 用 java.sql.Connection 类型也是一样的效果，下面是异常信息

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure



The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.

或者有时候：

Could not create connection to database server. Attempted reconnect 3 times. Giving up.

然而并不是每次都是上面的异常，有时候提示连接超过3次的异常，有时候说是超过多少毫秒。

package com.example.android_mysql_test;



import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.util.Log;

import com.mysql.jdbc.Connection;

import com.mysql.jdbc.PreparedStatement;

//import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

public class MainActivity extends AppCompatActivity {

    //声明Connection对象

    com.mysql.jdbc.Connection con;

    //驱动程序名

    String driver = "com.mysql.jdbc.Driver";

    //URL指向要访问的数据库名mydata

    String url = "jdbc:mysql://192.168.1.113:3306/dev001";//?autoReconnect=true&useUnicode=true&characterEncoding=UTF-8&useSSL=false&autoReconnect=true&failOverReadOnly=false;

    //MySQL配置时的用户名

    String user = "root";

    //MySQL配置时的密码

    String password = "1";

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);



        try {

            //加载驱动程序

            Class.forName(driver);

            //1.getConnection()方法，连接MySQL数据库！！

            con = (com.mysql.jdbc.Connection)DriverManager.getConnection(url, user, password);

            if (!con.isClosed())

                System.out.println("Succeeded connecting to the Database!");

            //2.创建statement类对象，用来执行SQL语句！！

            Statement statement = con.createStatement();

            //要执行的SQL语句

            String sql = "select * from 故障";

            //3.ResultSet类，用来存放获取的结果集！！

            ResultSet rs = statement.executeQuery(sql);





            String job = null;

            String id = null;

            while (rs.next()) {

                //获取stuname这列数据

                job = rs.getString("计算机名");

                //获取stuid这列数据

                id = rs.getString("最后在线时间");

                //输出结果

                Log.d("44445555",job);

                Log.d("44445555",id);

            }

            rs.close();

            con.close();

        } catch (ClassNotFoundException e) {

            //数据库驱动类异常处理

            System.out.println("Sorry,can`t find the Driver!");

            e.printStackTrace();

        } catch (SQLException e) {

            //数据库连接失败异常处理

            e.printStackTrace();

        } catch (Exception e) {

            // TODO: handle exception

            e.printStackTrace();

        } finally {

            System.out.println("数据库数据成功获取！！");

        }

    }



}