1、相機預覽方向適配

 public static void setCameraDisplayOrientation(Activity activity,
         int cameraId, android.hardware.Camera camera) {
     android.hardware.Camera.CameraInfo info =
             new android.hardware.Camera.CameraInfo();
     android.hardware.Camera.getCameraInfo(cameraId, info);
     int rotation = activity.getWindowManager().getDefaultDisplay()
             .getRotation();
     int degrees = 0;
     switch (rotation) {
         case Surface.ROTATION_0: degrees = 0; break;
         case Surface.ROTATION_90: degrees = 90; break;
         case Surface.ROTATION_180: degrees = 180; break;
         case Surface.ROTATION_270: degrees = 270; break;
     }

     int result;
     if (info.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {
         result = (info.orientation + degrees) % 360;
         result = (360 - result) % 360;  // compensate the mirror
     } else {  // back-facing
         result = (info.orientation - degrees + 360) % 360;
     }
     camera.setDisplayOrientation(result);
 }
 

2、相機對焦時掛掉

相機在非活動時對焦失敗，要在mCamera.startPreview()候才可以呼叫對焦的方法，保險做法是設定一個boolean值isPreviewActive判斷是否活動。當mCamera.stopPreview()時isPreviewActive=false;當mCamera.startPreview()時isPreviewActive=true，對焦時先判斷這個標誌位。
08-08 16:54:59.357   723 25306 E Camera2Client: autoFocus: Camera 0: Call autoFocus when preview is inactive (state = 1).
08-08 16:54:59.358  5205  5205 W System.err: java.lang.RuntimeException: autoFocus failed
08-08 16:54:59.358  5205  5205 W System.err:     at android.hardware.Camera.native_autoFocus(Native Method)
08-08 16:54:59.358  5205  5205 W System.err:     at android.hardware.Camera.autoFocus(Camera.java:1402)

3、自動對焦方式

程式碼設定了Camera.Parameters.FOCUS_MODE_AUTO，自動對焦效果並不好（相機模糊後並不會自動再次對焦），可以使用

Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE或者Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO來進行自動連續對焦，使用自動連續對焦需要呼叫mCamera.cancelAutoFocus()停止手動對焦

4、快門聲音

 public final void takePicture(ShutterCallback shutter, PictureCallback raw,
            PictureCallback postview, PictureCallback jpeg) 
 

呼叫takePicture拍照時，第一個引數為null則拍照無聲音，否則有快門聲