Android Camera+SurfaceView

      SurfaceHolder holder = source.getHolder();
        holder.addCallback(new SurfaceHolder.Callback() {
            @Override
            public void surfaceCreated(final SurfaceHolder holder) {
                Camera camera = Camera.open(Camera.CameraInfo.CAMERA_FACING_FRONT);
                try {
                    camera.setPreviewDisplay(holder);
                } catch (IOException e) {
                    e.printStackTrace();
                }
                camera.setDisplayOrientation(90);
                Camera.Size previewSize = camera.getParameters().getPreviewSize();
                final int width = previewSize.width;
                final int height = previewSize.height;
                System.out.println(width + ":" + height);
                camera.setPreviewCallback(new Camera.PreviewCallback() {
                    @Override
                    public void onPreviewFrame(byte[] data, Camera camera) {
                      
                    }
                });
                camera.startPreview();
            }

            @Override
            public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
            }

            @Override
            public void surfaceDestroyed(SurfaceHolder holder) {

            }
        });
    }

其中source是SurfaceView。
主要步骤如下：

1. SurfaceHolder.addCallback。
2. 在android.view.SurfaceHolder.Callback#surfaceCreated方法中，初始化摄像头相关。
3. 通过android.hardware.Camera#setPreviewDisplay 来绑定SurfaceHolder。
4. 调用android.hardware.Camera#startPreview来开始摄像。

这种情况下，视频直接渲染到surfaceView上边。如果要进行特殊操作。

1. 通过android.hardware.Camera#setPreviewCallback监听每一帧的回调。
2. 在回调中调用方法直接绘制到surfaceView上。

        Canvas canvas = surfaceHolder.lockCanvas();
        canvas.drawColor(0, android.graphics.PorterDuff.Mode.CLEAR);
        Bitmap cacheBitmap = nv21ToBitmap(data, width, height);
        canvas.drawBitmap(cacheBitmap, 0, 0, null);
        surfaceHolder.unlockCanvasAndPost(canvas);

 private static Bitmap nv21ToBitmap(byte[] nv21, int width, int height) {
        Bitmap bitmap = null;
        try {
            YuvImage image = new YuvImage(nv21, ImageFormat.NV21, width, height, null);
            ByteArrayOutputStream stream = new ByteArrayOutputStream();
            image.compressToJpeg(new Rect(0, 0, width, height), 80, stream);
            bitmap = BitmapFactory.decodeByteArray(stream.toByteArray(), 0, stream.size());
            stream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return bitmap;
    }