从活动通信到服务

Posted 2023-02-16

【中文标题】从活动通信到服务

【英文标题】：communicate to service from activity

【发布时间】：2013-05-30 17:35:49

【问题描述】：

我正在尝试与服务通信。我找到了这个android Guide。

我确实喜欢第一个示例，但我有一个错误：

"java.lang.RuntimeException: 无法绑定到服务 com.example.internetcall.MyService@41763970 与 Intent cmp=com.example.internetcall/.MyService ： java.lang.NullPointerException: println 需要一条消息”。

这是活动：

public class StartService extends Activity

String telephoneNumber;
TextView statusTextView, numberTextView;
MyService myService;
Boolean myBound;

ServiceConnection mConnection = new ServiceConnection() 

    @Override
    public void onServiceConnected(ComponentName arg0, IBinder arg1) 
        Log.i("bnf","qui");
        LocalBinder binder = (LocalBinder) arg1;
        myService = binder.getService();
        myBound = true;
    

    @Override
    public void onServiceDisconnected(ComponentName arg0) 
        myBound = false;
    
;

@Override
protected void onCreate(Bundle savedInstanceState) 
    super.onCreate(savedInstanceState);
    this.setContentView(R.layout.start_service_layout);

    statusTextView = (TextView) this.findViewById(R.id.statusTextView);
    numberTextView = (TextView) this.findViewById(R.id.numberTextView);

    Intent i = this.getIntent();
    telephoneNumber = i.getStringExtra("number");

    numberTextView.setText(telephoneNumber);

    if(isMyServiceRunning())
        statusTextView.setText("Online");
        statusTextView.setTextColor(Color.GREEN);
    else
        statusTextView.setText("Offline");
        statusTextView.setTextColor(Color.RED);
    

    Intent intent = new Intent(this, MyService.class);
    bindService(intent, mConnection, Context.BIND_AUTO_CREATE);

    //SupportClass.myService.setNumber(telephoneNumber);



private boolean isMyServiceRunning() 
    ActivityManager manager = (ActivityManager) getSystemService(ACTIVITY_SERVICE);
    for (RunningServiceInfo service : manager.getRunningServices(Integer.MAX_VALUE)) 
        if ("com.example.internetcall.MyService".equals(service.service.getClassName().toString())) 
             return true;
        
    
    return false;

这是我的服务：

public class MyService extends Service

MyWebSocket mws;
private final IBinder mBinder = new LocalBinder();
Boolean onCall;
String telephoneNumber;
String myTelephoneNumber = null;

@Override
public IBinder onBind(Intent arg0) 
    Log.i("bnf",arg0.getStringExtra("number"));
    return mBinder;


public class LocalBinder extends Binder 
    MyService getService() 
        Log.i("bnf","localbinder");
        // Return this instance of LocalService so clients can call public methods
        return MyService.this;
    

有人知道这个问题的解决方案吗？

如果我犯了一些语法错误，我很抱歉，但我不太懂英语。

【参考方案1】：

您的异常发生在Log.i("bnf",arg0.getStringExtra("number")); arg0.getStringExtra("number") 为空。您没有在绑定服务的意图中传递字符串“number”。