SurfaceHolder.Callback 必须在 SurfaceView构造(实例化)的时候add给SurfaceView的SurfaceHolder

SurfaceHolder.Callback 必须在 SurfaceView构造(实例化)的时候add给SurfaceView的SurfaceHolder，如果推出到后面的调用中add，那么Surface就无法创建，导致一系列的错误，比如我的代码中，因为Surface没有成功实例化，导致手动调用surfaceCreated()，然后报错：

09-16 23:00:11.067: E/AndroidRuntime(10421): FATAL EXCEPTION: main
09-16 23:00:11.067: E/AndroidRuntime(10421): Process: com.levin.mobilemonitor, PID: 10421
09-16 23:00:11.067: E/AndroidRuntime(10421): java.lang.RuntimeException: Only one Looper may be created per thread
09-16 23:00:11.067: E/AndroidRuntime(10421): at android.os.Looper.prepare(Looper.java:77)
09-16 23:00:11.067: E/AndroidRuntime(10421): at android.os.Looper.prepare(Looper.java:72)
09-16 23:00:11.067: E/AndroidRuntime(10421): at org.webrtc.videoengine.VideoCaptureAndroid.setupCamera(VideoCaptureAndroid.java:1637)
09-16 23:00:11.067: E/AndroidRuntime(10421): at org.webrtc.videoengine.VideoCaptureAndroid.openCamera(VideoCaptureAndroid.java:1136)
09-16 23:00:11.067: E/AndroidRuntime(10421): at org.webrtc.videoengine.VideoCaptureAndroid.surfaceCreated(VideoCaptureAndroid.java:777)
09-16 23:00:11.067: E/AndroidRuntime(10421): at android.view.SurfaceView.updateWindow(SurfaceView.java:572)
09-16 23:00:11.067: E/AndroidRuntime(10421): at android.view.SurfaceView.access$000(SurfaceView.java:86)
09-16 23:00:11.067: E/AndroidRuntime(10421): at android.view.SurfaceView$3.onPreDraw(SurfaceView.java:175)
09-16 23:00:11.067: E/AndroidRuntime(10421): at android.view.ViewTreeObserver.dispatchOnPreDraw(ViewTreeObserver.java:847)
09-16 23:00:11.067: E/AndroidRuntime(10421): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1913)
09-16 23:00:11.067: E/AndroidRuntime(10421): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1042)
09-16 23:00:11.067: E/AndroidRuntime(10421): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5721)
09-16 23:00:11.067: E/AndroidRuntime(10421): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761)
09-16 23:00:11.067: E/AndroidRuntime(10421): at android.view.Choreographer.doCallbacks(Choreographer.java:574)
09-16 23:00:11.067: E/AndroidRuntime(10421): at android.view.Choreographer.doFrame(Choreographer.java:544)
09-16 23:00:11.067: E/AndroidRuntime(10421): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747)
09-16 23:00:11.067: E/AndroidRuntime(10421): at android.os.Handler.handleCallback(Handler.java:733)
09-16 23:00:11.067: E/AndroidRuntime(10421): at android.os.Handler.dispatchMessage(Handler.java:95)
09-16 23:00:11.067: E/AndroidRuntime(10421): at android.os.Looper.loop(Looper.java:136)
09-16 23:00:11.067: E/AndroidRuntime(10421): at android.app.ActivityThread.main(ActivityThread.java:5050)
09-16 23:00:11.067: E/AndroidRuntime(10421): at java.lang.reflect.Method.invokeNative(Native Method)
09-16 23:00:11.067: E/AndroidRuntime(10421): at java.lang.reflect.Method.invoke(Method.java:515)
09-16 23:00:11.067: E/AndroidRuntime(10421): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:805)
09-16 23:00:11.067: E/AndroidRuntime(10421): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:621)
09-16 23:00:11.067: E/AndroidRuntime(10421): at dalvik.system.NativeStart.main(Native Method)
09-16 23:00:11.137: I/Process(10421): Sending signal. PID: 10421 SIG: 9

1.如果SurfaceView定义在layout.xml中，在onCreate中，确切地说是在setContentView后面，调用holder.addCallback(callback);：

 */
public class CameraActivity extends Activity implements SurfaceHolder.Callback {
  
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    
    SurfaceView surface = (SurfaceView)findViewById(R.id.surfaceView);
    SurfaceHolder holder = surface.getHolder();
    holder.addCallback(this);

2.如果是自定义的SurfaceView，在构造函数中，确切地说是在super(context)后面，调用holder.addCallback(callback)  ：

    public VideoCaptureAndroid(Context context) {
        super(context);
        mContext = context;
        instance = this;
        
        //levin ---begin, 将mHolder.addCallback(this)initVideoCaptureAndroid移到这里
        //否则crash: Only one Looper may be created per thread
        // Install a SurfaceHolder.Callback so we get notified when the
        // underlying surface is created and destroyed.
        mHolder = getHolder();
        mHolder.addCallback(this);  
        // deprecated setting, but required on Android versions prior to 3.0
        mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); // deprecated
        //levin ---end
    }