深入Android线程的相关问题解惑

public class ActivityDemo extends Activity {
    private static final String TAG = "ActivityDemo";
    private Handler mMainHandler = new Handler(new Handler.Callback() {
 public boolean handleMessage(Message msg) {
     dumpThreadInfo();
     return false;
 }
    });

    @Override
    protected void onCreate(Bundle savedInstanceState) {
 dumpThreadInfo();
 super.onCreate(savedInstanceState);

 // add four buttons
 LinearLayout layout = new LinearLayout(getApplication());
 layout.setOrientation(LinearLayout.VERTICAL);
 Button startService = new Button(getApplication());
 startService.setText("Start a Service");
 startService.setOnClickListener(new View.OnClickListener() {
     public void onClick(View v) {
  Intent i = new Intent(getApplication(), ServiceDemo.class);
  startService(i);
     }
 });
 layout.addView(startService);
 Button startAnother = new Button(getApplication());
 startAnother.setText("Start another Activity");
 startAnother.setOnClickListener(new View.OnClickListener() {
     public void onClick(View v) {
  Intent i = new Intent(getApplication(), AnotherActivity.class);
  startService(i);
     }
 });
 layout.addView(startAnother);
 Button startCOntentProvider= new Button(getApplication());
 startContentProvider.setText("Start a ContentProvider");
 startContentProvider.setOnClickListener(new View.OnClickListener() {
     public void onClick(View v) {
  getContentResolver().query(ContentProviderDemo.CONTENT_URI, null, null, null, null);
     }
 });
 layout.addView(startContentProvider);
 Button startReceiver = new Button(getApplication());
 startReceiver.setText("Start a BroadcastReceiver");
 startReceiver.setOnClickListener(new View.OnClickListener() {
     public void onClick(View v) {
  Intent i = new Intent("android.action.start_broadcastreceiver_demo");
  sendBroadcast(i);
     }
 });
 layout.addView(startReceiver);
 setContentView(layout);

 mMainHandler.sendEmptyMessageDelayed(0, 500);
    }

    public void dumpThreadInfo() {
 Thread.dumpStack();
 Log.e(TAG, Thread.currentThread().toString());
 Log.e(TAG, " " + getMainLooper());
    }
}

public class AnotherActivity extends Activity {
    private static final String TAG = "AnotherActivity";
    private Handler mMainHandler = new Handler(getMainLooper(), new Handler.Callback() {
        public boolean handleMessage(Message msg) {
            // this will cause ANR
            Log.e(TAG, "you know what this is very slow slow slow slow");
            SystemClock.sleep(20 * 1000);
            dumpThreadInfo();
            return false;
        }
    });
    @Override
    protected void onCreate(Bundle savedInstanceState) {
 dumpThreadInfo();
 super.onCreate(savedInstanceState);

 setTitle("this is another activity");
 mMainHandler.sendEmptyMessageDelayed(0, 500);
    }
    @Override
    protected void onDestroy() {
 dumpThreadInfo();
 super.onDestroy();
    }
    public void dumpThreadInfo() {
 Thread.dumpStack();
 Log.e(TAG, Thread.currentThread().toString());
 Log.e(TAG, " " + getMainLooper());
    }
}

public class ServiceDemo extends Service {
    private Handler mMainHandler = new Handler(new Handler.Callback() {
        public boolean handleMessage(Message msg) {
            // this will cause ANR, too
            Log.e(TAG, "this is very slow you know, slow slow");
            SystemClock.sleep(20 * 1000);
            dumpThreadInfo();
            return false;
        }
    });
    private static final String TAG = "ServiceDemo";
    @Override
    public IBinder onBind(Intent arg0) {
 dumpThreadInfo();
 return null;
    }
    @Override
    public void onCreate() {
 dumpThreadInfo();
 super.onCreate();
 mMainHandler.sendEmptyMessageDelayed(0, 500);
    }
    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
 dumpThreadInfo();
 return super.onStartCommand(intent, flags, startId);
    }

    public void dumpThreadInfo() {
 Thread.dumpStack();
 Log.e(TAG, Thread.currentThread().toString());
 Log.e(TAG, " " + getMainLooper());
    }
}

public class ContentProviderDemo extends ContentProvider {
    public static final Uri CONTENT_URI = Uri.parse("content://com.hilton.effectiveandroid.app/content");
    private static final String TAG = "ContentProviderDemo";
    @Override
    public int delete(Uri arg0, String arg1, String[] arg2) {
 dumpThreadInfo();
 return 0;
    }
    @Override
    public Uri insert(Uri uri, ContentValues values) {
 dumpThreadInfo();
 return null;
    }
    @Override
    public boolean onCreate() {
 dumpThreadInfo();
 return false;
    }
    @Override
    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
 dumpThreadInfo();
 // it will cause ANR of course
 Log.e(TAG, "this is very slow, you know that");
 SystemClock.sleep(20 * 1000);
 return null;
    }
    @Override
    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
 dumpThreadInfo();
 return 0;
    }

    public void dumpThreadInfo() {
 Thread.dumpStack();
 Log.e(TAG, Thread.currentThread().toString());
    }
    @Override
    public String getType(Uri arg0) {
 return null;
    }
}

public class BroadcastReceiverDemo extends BroadcastReceiver {
    private static final String TAG = "BroadcastReceiverDemo";
    @Override
    public void onReceive(Context context, Intent intent) {
 Log.e(TAG, "intent is " + intent);
 dumpThreadInfo();
    }

    public void dumpThreadInfo() {
 Thread.dumpStack();
 Log.e(TAG, Thread.currentThread().toString());
    }
}