java - 无法使用 JDBC 将 Android 应用程序连接到使用 XAMPP 的 MYSQL 数据库

Question

我正在使用 android studio 开发一个 android 应用程序，以使用 XAMPP 直接连接到 MYSQL 数据库，但我无法这样做。我收到以下错误消息。

com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException:
Could not create connection to database server.

我的JAVA文件代码

import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;


public class MysqlSample01Activity extends ActionBarActivity {


    private static final String url = jdbc:mysql://172.25.2.5:3306/students";
    private static final String user = "roots";
    private static final String pass = "password";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_mysql_sample01);

        testDB();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_mysql_sample01, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }




    /** Called when the activity is first created. */


   void testDB() {


        TextView tv = (TextView)this.findViewById(R.id.text_view);
        try {
            Class.forName("com.mysql.jdbc.Driver");
            Connection con = DriverManager.getConnection(url, user, pass);
            /* System.out.println("Databaseection success"); */

            String result = "Database connection success\n";
            Statement st = con.createStatement();
            ResultSet rs = st.executeQuery("select * from users");
            ResultSetMetaData rsmd = rs.getMetaData();

            while(rs.next()) {
                result += rsmd.getColumnName(1) + ": " + rs.getInt(1) + "\n";
                result += rsmd.getColumnName(2) + ": " + rs.getString(2) + "\n";
                result += rsmd.getColumnName(3) + ": " + rs.getString(3) + "\n";
            }
            tv.setText(result);
        }
        catch(Exception e) {
            e.printStackTrace();
            tv.setText(e.toString());
        }

    }


}

我还向 list 文件添加了权限，如下所示

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.androidsql.mysqlsample01activity" >


    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />


    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >



        <activity
            android:name=".MysqlSample01Activity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

我已使用此链接 http://mvnrepository.com/artifact/mysql/mysql-connector-java/5.1.36 中的 JDBC 库

Answer 1

您可以/不得访问 Android 上的直接数据库。对于如何使用 Xampp 服务器的初学者研究如何响应包含数据集的 JSON，然后在 Android 上获取它。