android - 在 Android Studio 3.0.1 中使用 OpenCV

Question

我在带有 android studio3.0.1 的应用程序中使用 opencv 2.4.9 库使用 Nexus 4 API 27(Android 8.1.0 API 27) 虚拟设备运行我的应用程序我正在学习本教程: https://www.youtube.com/watch?v=Z2vrioEr9OI&t=1216s

在我的项目中链接 Android.mk 路径并运行应用程序后我得到了一个错误

E/AndroidRuntime: FATAL EXCEPTION: main
                      Process: com.example.carla.carla, PID: 20817
                      java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.carla.carla/com.example.carla.carla.MainActivity}: java.lang.ClassCastException: com.example.carla.carla.MainActivity cannot be cast to org.opencv.android.CameraBridgeViewBase$CvCameraViewListener
                          at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2778)
                          at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856)
                          at android.app.ActivityThread.-wrap11(Unknown Source:0)
                          at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589)
                          at android.os.Handler.dispatchMessage(Handler.java:106)
                          at android.os.Looper.loop(Looper.java:164)
                          at android.app.ActivityThread.main(ActivityThread.java:6494)
                          at java.lang.reflect.Method.invoke(Native Method)
                          at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
                          at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
                       Caused by: java.lang.ClassCastException: com.example.carla.carla.MainActivity cannot be cast to org.opencv.android.CameraBridgeViewBase$CvCameraViewListener
                          at com.example.carla.carla.MainActivity.onCreate(MainActivity.java:52)
                          at android.app.Activity.performCreate(Activity.java:7009)
                          at android.app.Activity.performCreate(Activity.java:7000)
                          at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1214)
                          at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2731)
                          at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856) 
                          at android.app.ActivityThread.-wrap11(Unknown Source:0) 
                          at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589) 
                          at android.os.Handler.dispatchMessage(Handler.java:106) 
                          at android.os.Looper.loop(Looper.java:164) 
                          at android.app.ActivityThread.main(ActivityThread.java:6494) 
                          at java.lang.reflect.Method.invoke(Native Method) 
                          at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438) 
                          at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807) 

当我清理并重建项目时，文件夹 ndk/debug/android.mk 消失了，我得到了这个错误

Error:A problem occurred configuring project ':app'.
Gradle project ndkBuild.path is C:\Users\Carla\AndroidStudioProjects\Carla\app\build\intermediates\ndk\debug\Android.mk

但是那个文件不存在

这是 MainActivity 类

 package com.example.carla.carla;

  import android.support.v7.app.AppCompatActivity;
  import android.os.Bundle;
  import android.util.Log;
  import android.view.SurfaceView;
  import org.opencv.android.BaseLoaderCallback;
  import org.opencv.android.CameraBridgeViewBase;
  import org.opencv.android.JavaCameraView;
  import org.opencv.android.OpenCVLoader;
  import org.opencv.android.LoaderCallbackInterface;
  import org.opencv.core.Mat;
  import org.opencv.core.CvType;


 public class MainActivity extends AppCompatActivity implements 
 CameraBridgeViewBase.CvCameraViewListener2 {
   private static final String TAG = "MainActivity";
JavaCameraView javaCameraView;
Mat mRGba;
  private BaseLoaderCallback mLoaderCallBack;

{
    mLoaderCallBack = new BaseLoaderCallback(this) {
        @Override
        public void onManagerConnected(int status) {
            switch (status) {
                case BaseLoaderCallback.SUCCESS: {
                    javaCameraView.enableView();
                    mRGba = new Mat();
                }
                break;

                default: {
                    super.onManagerConnected(status);

                }
                break;
            }

        }
    };
}


protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
javaCameraView= (JavaCameraView)findViewById(R.id.java_camera_view);
javaCameraView.setVisibility(SurfaceView.VISIBLE);



  javaCameraView.setCvCameraViewListener
   ((CameraBridgeViewBase.CvCameraViewListener) this);
       }
@Override
protected  void onPause(){
super.onPause();
if (javaCameraView!=null)
   javaCameraView.disableView();
}

 @Override
  protected void onDestroy(){
  super.onDestroy();
  if (javaCameraView!=null)
    javaCameraView.disableView();
   }

    @Override
    protected  void onResume(){
     super.onResume();

      if(!OpenCVLoader.initDebug()) {
      Log.d(TAG, "Opencv loaded");
      mLoaderCallBack.onManagerConnected(LoaderCallbackInterface.SUCCESS);
     } else {
        Log.d(TAG, " Opencv not loaded");
        OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_2_4_9, this, 
        mLoaderCallBack);
     }}

 @Override
  public void onCameraViewStarted(int width, int height) {
    mRGba = new Mat(height, width, CvType.CV_8UC4);

   }

 @Override
   public void onCameraViewStopped() {
     mRGba.release();
    }

@Override
public Mat onCameraFrame(CameraBridgeViewBase.CvCameraViewFrame inputFrame) 
  {
   mRGba = inputFrame.rgba();
   return mRGba;
}
 };

Answer 1

com.example.carla.carla.MainActivity cannot be cast to org.opencv.android.CameraBridgeViewBase$CvCameraViewListener

您需要在 MainActivity 中实现 CvCameraViewListener。

如果您复制了 CameraBridgeViewBase 并将其更改为您的 MainActivity，则您也需要更改引用。