Android 바인드 서비스 문제

Question

클래스의 plainText = mService.getPlainText(key, cipherText);이 오류를 일으키는 이유를 모르겠습니다. 라인을 buttonclick에 넣으면 작동합니다. 아무도 나에게 무엇이 잘못되었는지 설명 할 수 있습니까?

public class CrackingProcess extends Activity { 

TextView message; 
TextView result; 
DesService mService; 
boolean mBound = false; 
Button btnStop; 
String[] stringResult; 
String key; 
String cipherText; 
String plainText; 

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

    message = (TextView) findViewById(R.id.message); 
    btnStop = (Button) findViewById(R.id.btnStop); 
    result = (TextView) findViewById(R.id.result); 
    message.setText("Cracking In Progress..."); 

    doBindService(); 
} 

@Override 
protected void onStart() { 
    super.onStart(); 

    try {  
     AssetManager fileManager = getAssets(); 
     InputStream fileInput = fileManager.open("json_block56"); 
     Reader fileRead = new InputStreamReader(fileInput); 
     JsonReader reader = new JsonReader(fileRead); 

     stringResult = readJson(reader); 

     key = stringResult[1]; 
     Log.d("key", key); 
     cipherText = stringResult[2]; 
     Log.d("text", cipherText); 

     plainText = mService.getPlainText(key, cipherText); // This line cause error 
     result.setText(plainText); 

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


    btnStop.setOnClickListener(new View.OnClickListener() { 

     @Override 
     public void onClick(View arg0) {  
      if (mBound) { 
       unbindService(mConnection); 
       mBound = false; 
      } 
      finish(); 
     } 
    }); 
} 

private String[] readJson(JsonReader reader) throws IOException { 
    String[] array = new String[3]; 
    String type = ""; 
    String key = ""; 
    String cipherText = ""; 
// ArrayList<String> result = null; 

    reader.beginObject(); 
    while (reader.hasNext()) { 
     String name = reader.nextName(); 
     if (name.equals("reply")) { 
      reader.beginObject(); 
      while (reader.hasNext()) { 
       String newName = reader.nextName(); 
       if (newName.equals("type")) 
        type = reader.nextString(); 
       else if (newName.equals("key")) 
        key = reader.nextString(); 
       else if (newName.equals("ciphertext")) 
        cipherText = reader.nextString(); 
       else 
        reader.skipValue(); 
      } 
      reader.endObject(); 
     } else 
      reader.skipValue(); 
    } 
    reader.endObject(); 

    array[0] = type; 
    array[1] = key; 
    array[2] = cipherText; 

    return array; 
} 

public ServiceConnection mConnection = new ServiceConnection() { 

    @Override 
    public void onServiceConnected(ComponentName name, IBinder service) { 
     mService = ((DesService.LocalBinder)service).getService(); 
     mBound = true; 
    } 

    @Override 
    public void onServiceDisconnected(ComponentName name) { 
     mService = null; 
     //mBound = false; 
    } 

}; 

void doBindService() { 
    Intent intent = new Intent(this, DesService.class); 
    startService(intent); 
    boolean bound = bindService(intent, mConnection, Context.BIND_AUTO_CREATE); 

    if (bound) { 
     Log.d("Sucess", "Successfully bound to service"); 
    } 
    else { 
     Log.d("Fail", "Failed to bind service"); 
    } 
} 

}

DESService 클래스 서비스에 대한 실제 연결이 아직 사실 true를 반환 bindService() 방법에도 불구하고 설립되지 않은

10-05 18:29:13.893: D/AndroidRuntime(8026): Shutting down VM 
10-05 18:29:13.893: W/dalvikvm(8026): threadid=1: thread exiting with uncaught exception (group=0xa62c5288) 
10-05 18:29:13.897: E/AndroidRuntime(8026): FATAL EXCEPTION: main 
10-05 18:29:13.897: E/AndroidRuntime(8026): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.androiddes/com.example.androiddes.CrackingProcess}: java.lang.NullPointerException 
10-05 18:29:13.897: E/AndroidRuntime(8026):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059) 
10-05 18:29:13.897: E/AndroidRuntime(8026):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084) 
10-05 18:29:13.897: E/AndroidRuntime(8026):  at android.app.ActivityThread.access$600(ActivityThread.java:130) 
10-05 18:29:13.897: E/AndroidRuntime(8026):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195) 
10-05 18:29:13.897: E/AndroidRuntime(8026):  at android.os.Handler.dispatchMessage(Handler.java:99) 
10-05 18:29:13.897: E/AndroidRuntime(8026):  at android.os.Looper.loop(Looper.java:137) 
10-05 18:29:13.897: E/AndroidRuntime(8026):  at android.app.ActivityThread.main(ActivityThread.java:4745) 
10-05 18:29:13.897: E/AndroidRuntime(8026):  at java.lang.reflect.Method.invokeNative(Native Method) 
10-05 18:29:13.897: E/AndroidRuntime(8026):  at java.lang.reflect.Method.invoke(Method.java:511) 
10-05 18:29:13.897: E/AndroidRuntime(8026):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) 
10-05 18:29:13.897: E/AndroidRuntime(8026):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 
10-05 18:29:13.897: E/AndroidRuntime(8026):  at dalvik.system.NativeStart.main(Native Method) 
10-05 18:29:13.897: E/AndroidRuntime(8026): Caused by: java.lang.NullPointerException 
10-05 18:29:13.897: E/AndroidRuntime(8026):  at com.example.androiddes.CrackingProcess.onStart(CrackingProcess.java:63) 
10-05 18:29:13.897: E/AndroidRuntime(8026):  at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1163) 
10-05 18:29:13.897: E/AndroidRuntime(8026):  at android.app.Activity.performStart(Activity.java:5018) 
10-05 18:29:13.897: E/AndroidRuntime(8026):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2032) 
10-05 18:29:13.897: E/AndroidRuntime(8026):  ... 11 more 

Answer 1

긍정적 인 결과가 bindService() 일 경우 이이됩니다. 이미 발생했기 때문에, mService은 null이됩니다.

귀하의 전화 번호 plainText = mService.getPlainText(key, cipherText);은 onServiceConnected()-이전 또는 이후에만 사용할 수 있습니다.

Answer 2

public class DesService extends Service { 

private final IBinder mBinder = new LocalBinder(); 

@Override 
public IBinder onBind(Intent intent) { 
    return mBinder; 
} 

@Override 
public void onCreate() { 
    // TODO Auto-generated method stub 
    super.onCreate(); 
} 

@Override 
public int onStartCommand(Intent intent, int flags, int startId) { 
    // TODO Auto-generated method stub 
    return super.onStartCommand(intent, flags, startId); 
} 

public class LocalBinder extends Binder { 

    public DesService getService() { 
     return DesService.this; 
    } 

} 

public String getPlainText(String key, String cipherText) { 
    return "testing"; 
} 

} 

로그 캣.

다른 프로세스 (IPC)의 서비스에 바인딩하는 것은 비동기입니다. onServiceConnected()이 호출 될 때까지 서비스를 사용할 수 없습니다. onStart()은 그 과정에서 너무 일찍이므로 mService은 null입니다.

이렇게하면 단추를 클릭하는 수신기에 코드를 삽입하는 것이 왜 효과적인지 설명합니다. 버튼을 탭하면 연결이 설정됩니다.

Answer 3

getPlainText 메서드를 호출하면 null 포인터 예외가 발생하여 mService 개체가 초기화되지 않은 것처럼 보입니다.

이 OnServiceConnected으로 초기화 될 때까지 getPlainText으로 전화를 대기하십시오.