使用OpenCv with Android Camera Surfaceview时OpenCVLoader失败问题

今天在使用OpenCV Library 2.4.10建立了我的第一个基于opencv的Android程序，先贴出我的代码：

package com.example.facedetector;import org.opencv.android.BaseLoaderCallback;import org.opencv.android.CameraBridgeViewBase;import org.opencv.android.CameraBridgeViewBase.CvCameraViewFrame;import org.opencv.android.CameraBridgeViewBase.CvCameraViewListener2;import org.opencv.android.LoaderCallbackInterface;import org.opencv.android.OpenCVLoader;import org.opencv.core.Core;import org.opencv.core.CvType;import org.opencv.core.Mat;import org.opencv.core.MatOfRect;import org.opencv.core.Point;import org.opencv.core.Rect;import org.opencv.core.Scalar;import org.opencv.highgui.Highgui;import org.opencv.imgproc.Imgproc;import org.opencv.objdetect.CascadeClassifier;import android.app.Activity;import android.os.Bundle;import android.view.Menu;import android.view.MenuItem;import android.view.SurfaceView;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;public class MainActivity extends Activity implements CvCameraViewListener2, OnClickListener {private Button btnStart;private CameraBridgeViewBase cameraPreview = null; private Mat mRgba; private boolean startProcess = false;protected BaseLoaderCallback  mLoaderCallback = new BaseLoaderCallback(this) {@Overridepublic void onManagerConnected(int status) {switch (status) {case LoaderCallbackInterface.SUCCESS:{cameraPreview.enableView();} break;default:{super.onManagerConnected(status);} break;}}};@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);cameraPreview = (CameraBridgeViewBase) findViewById(R.id.cameraView);cameraPreview.setVisibility(SurfaceView.VISIBLE);cameraPreview.setCvCameraViewListener(this);btnStart = (Button) findViewById(R.id.btnStart);btnStart.setOnClickListener(this);}@Overrideprotected void onResume() {super.onResume();<strong>OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_2_4_10, getApplicationContext(), mLoaderCallback );</strong>}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {// Inflate the menu; this adds items to the action bar if it is present.getMenuInflater().inflate(R.menu.main, menu);return true;}@Overridepublic boolean onOptionsItemSelected(MenuItem item) {// Handle action bar item clicks here. The action bar will// automatically handle clicks on the Home/Up button, so long// as you specify a parent activity in AndroidManifest.xml.int id = item.getItemId();if (id == R.id.action_settings) {return true;}return super.onOptionsItemSelected(item);}private void startFaceDetetion(Mat image){String xmlfilePath=getClass().getResource("lbpcascade_frontalface.xml").getPath().substring(1);  CascadeClassifier faceDetector = new CascadeClassifier(xmlfilePath);  // Detect faces in the image.  // MatOfRect is a special container class for Rect.  MatOfRect faceDetections = new MatOfRect();  faceDetector.detectMultiScale(image, faceDetections);  System.out.println(String.format("Detected %s faces", faceDetections.toArray().length));  // Draw a bounding box around each face.  for (Rect rect : faceDetections.toArray()) {  Scalar color = new Scalar(0, 255, 0);Core.rectangle(image, new Point(rect.x, rect.y), new Point(rect.x + rect.width, rect.y + rect.height), color);} }@Overrideprotected void onDestroy() {super.onDestroy();        if (cameraPreview != null) {        cameraPreview.disableView();        startProcess = false;        }}@Overrideprotected void onPause() {super.onPause();if(cameraPreview != null){cameraPreview.disableView();startProcess = false;}}@Overridepublic void onCameraViewStarted(int width, int height) {mRgba =  new Mat(height, width, CvType.CV_8UC4);}@Overridepublic void onCameraViewStopped() {mRgba.release();}@Overridepublic Mat onCameraFrame(CvCameraViewFrame inputFrame) {    if(startProcess == true){    mRgba = inputFrame.rgba();

                return mRgba    }    return null;}@Overridepublic void onClick(View v) {startProcess = !startProcess;}}

这段代码，按照Internet上各位前辈们的经验总结，是没有问题的，但是当我在真正run它的时候，还是出现了问题，logcat上出现了以下提示：

08-18 20:57:03.549: E/AndroidRuntime(3444): java.lang.RuntimeException: Unable to resume activity {com.example.facedetector/com.example.facedetector.MainActivity}: java.lang.IllegalArgumentException: Service Intent must be explicit: Intent { act=org.opencv.engine.BIND }

也就是说OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_2_4_10, getApplicationContext(), mLoaderCallback );无法运行成功。

网络上也有人遇到了同样的问题，给出的解决方案是：

Try using getApplicationContext() instead of this in OpenCVLoader.initAsync(..)

但是我在修改后，程序依然无法运行。

出现上述问题的原因主要是因为使用了Android 5.0作为targetsdk，专业的解释 in here。这里我就不多说，大家可以自行研究。简单解释是：

Android 5.0 service intents must be explicit intents and the OpenCV library uses implicit intents in the
AsyncServiceHelper.java ( new Intent("org.opencv.engine.BIND") ), so it doesn't work.

既然是因为SDK version 的问题，那么只需要改变version就可以了，因此这里我将我的targetsdk由API 21改为了API 19：

android:targetSdkVersion="21"  --------->  android:targetSdkVersion="19"

问题解决了，这时候就可以正常运行APP了。