Android経由のMySQL接続エラー

Question

私のAndroidプロジェクトに少し問題があります。 私のMySQLデータベースのデータをリストに入れたいのですが、アンドロイドはそれに接続しません。

MySQLConnector:

private static Connection con = null; 

private static String dbHost = "85.214.101.213"; // changed the ip :) 
private static String dbPort = "3306"; // Port -- Standard: 3306 
private static String dbName = "ticketsystem"; // Datenbankname 
private static String dbUser = "admin"; // Datenbankuser 
private static String dbPass = "root"; // Datenbankpasswort 

public static void conect() { 
    try { 
     Class.forName("com.mysql.jdbc.Driver"); // Datenbanktreiber für JDBC 

     System.out.println("jdbc:mysql://" + dbHost + ":" + dbPort + "/" + dbName + "?" + "user=" 
       + dbUser + "&" + "password=" + dbPass); 

     con = DriverManager.getConnection("jdbc:mysql://" + dbHost + ":" + dbPort + "/" + dbName + "?" + "user=" 
       + dbUser + "&" + "password=" + dbPass); 




    } catch (ClassNotFoundException e) { 
     System.out.println("Treiber nicht gefunden"); 
    } catch (SQLException e) { 
     System.out.println(e); 
     System.out.println("Verbindung nicht moglich"); 
     System.out.println("SQLException: " + e.getMessage()); 
     System.out.println("SQLState: " + e.getSQLState()); 
     System.out.println("VendorError: " + e.getErrorCode()); 
    } 


} 

SQLManager:

public SQLManager() { 
    MySQLConnection.conect(); 
    Log.e("test", "nach conect"); 
    con = MySQLConnection.getCon(); 
} 


public String[] getFreeEvents() { 

    ArrayList<String> mList = new ArrayList(); 

    try 
    { 
     PreparedStatement ps = con.prepareStatement(" SELECT `EventID`,`Name`,`Zeit`,`Ort` FROM `event` WHERE `freeTickets` >= ?"); 

     ps.setInt(1, 0); 
     ResultSet rs = ps.executeQuery(); 
     while (rs.next()) 
     { 
      int EventID = rs.getInt("EventID"); 
      String Name = rs.getString("Name"); 
      String Zeit = rs.getString("Zeit"); 
      String Ort = rs.getString("Ort"); 

      String info = Name +"," + Zeit + ","+Ort ; 

      mList.add(info); 
      System.out.println(info); 
     } 


    } 
    catch (SQLException e) 
    { 
     e.printStackTrace(); 
    } 

    String[] array = mList.toArray(new String[0]); 
    return array; 
} 

And the Class form the Android activity:

Button b; 
ListView list; 
EditText vor; 
TextView nach; 
SQLManager man = new SQLManager(); 
@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_new_ticket); 
    setContentView(R.layout.activity_main); 
    b = findViewById(R.id.button); 
    b.setOnClickListener(this); 
    list = findViewById(R.id.list); 
    list.setAdapter(new ArrayAdapter<String>(this, 
      android.R.layout.simple_list_item_1, man.getFreeEvents())); //here is the SQL request... 
    vor = findViewById(R.id.editText); 
    nach = findViewById(R.id.editText2); 
} 

マイprobemはAndroidがconnctionを開くことができませんでしたということです。

は、ここに私のコードです。 私はAndroidのマニフェストに許可要求を追加しました：

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

だから、少なくとも私はこのエラーを得た：

I/System.out: `com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server.´ 
I/System.out: Verbindung nicht moglich 
I/System.out: SQLException: Could not create connection to database server. 
I/System.out: SQLState: 08001 
I/System.out: VendorError: 0 
E/test: nach conect 
D/AndroidRuntime: Shutting down VM 
E/AndroidRuntime: FATAL EXCEPTION: main 
        Process: ml.gottfried.myapp, PID: 10440 
        java.lang.RuntimeException: Unable to start activity ComponentInfo{ml.gottfried.myapp/ml.gottfried.myapp.NewTicket}: java.lang.NullPointerException: Attempt to invoke interface method 'java.sql.PreparedStatement java.sql.Connection.prepareStatement(java.lang.String)' on a null object reference 
         at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2665) 
         at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726) 
         at android.app.ActivityThread.-wrap12(ActivityThread.java) 
         at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477) 
         at android.os.Handler.dispatchMessage(Handler.java:102) 
         at android.os.Looper.loop(Looper.java:154) 
         at android.app.ActivityThread.main(ActivityThread.java:6119) 
         at java.lang.reflect.Method.invoke(Native Method) 
         at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886) 
         at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776) 
        Caused by: java.lang.NullPointerException: Attempt to invoke interface method 'java.sql.PreparedStatement java.sql.Connection.prepareStatement(java.lang.String)' on a null object reference 
         at ml.gottfried.myapp.SQLManager.getFreeEvents(SQLManager.java:82) 
         at ml.gottfried.myapp.NewTicket.onCreate(NewTicket.java:43) 
         at android.app.Activity.performCreate(Activity.java:6679) 
         at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118) 
         at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2618) 
         at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2726)  
         at android.app.ActivityThread.-wrap12(ActivityThread.java)  
         at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477)  
         at android.os.Handler.dispatchMessage(Handler.java:102)  
         at android.os.Looper.loop(Looper.java:154)  
         at android.app.ActivityThread.main(ActivityThread.java:6119)  
         at java.lang.reflect.Method.invoke(Native Method)  
         at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)  
         at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)  

私はあなたが私に

感謝:)

を助けることを願って

PS：何か疑問がある場合はお問い合わせください:)

Answer 1

多くが考えて、これは私を助け：

が接続MethodeのにMySQLConnectorに

 StrictMode.ThreadPolicy policy = new`StrictMode.ThreadPolicy.Builder().permitAll().build(); 
    StrictMode.setThreadPolicy(policy); 

を追加し、Androidのマニフェストに

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

を追加します。

私のデバイスと私のデータベースとの接続が完了しました:)