java - 如何从 Android 服务实现 FileObserver

Question

你如何构建一个 Android 应用程序来启动一个 Service 以使用一个 FileObserver 以便当观察到的目录被修改(即用户拍照)时执行一些其他代码.调试时，永远不会触发 onEvent 方法。

这是我的服务中的 onStart 事件。 Toast 触发“My Service Started...”

public final String TAG = "DEBUG";
public static FileObserver observer;    

@Override
public void onStart(Intent intent, int startid) {       
        Log.d(TAG, "onStart");

        final String pathToWatch = android.os.Environment.getExternalStorageDirectory().toString() + "/DCIM/Camera/";       
        Toast.makeText(this, "My Service Started and trying to watch " + pathToWatch, Toast.LENGTH_LONG).show();

        observer = new FileObserver(pathToWatch) { // set up a file observer to watch this directory on sd card
            @Override
            public void onEvent(int event, String file) {
                //if(event == FileObserver.CREATE && !file.equals(".probe")){ // check if its a "create" and not equal to .probe because thats created every time camera is launched
                    Log.d(TAG, "File created [" + pathToWatch + file + "]");

                    Toast.makeText(getBaseContext(), file + " was saved!", Toast.LENGTH_LONG);                  
                //}
            }
        };
    }

但是在 Toast 之后，如果我拍照，onEvent 永远不会触发。这是由调试决定的。它永远不会达到那个断点，并且 Toast 永远不会触发。

浏览该目录时，新图像会保存在那里。

如何让 FileObserver 在 Service 中工作？

Answer 1

请see这个帖子。我认为您在设置观察者后错过了 observer.startWatching() 调用。

 observer = new FileObserver(pathToWatch) { // set up a file observer to watch this directory on sd card

     @Override
     public void onEvent(int event, String file) {
         //if(event == FileObserver.CREATE && !file.equals(".probe")){ // check if its a "create" and not equal to .probe because thats created every time camera is launched
         Log.d(TAG, "File created [" + pathToWatch + file + "]");

         Toast.makeText(getBaseContext(), file + " was saved!", Toast.LENGTH_LONG).show();
         //}
     }
 };
 observer.startWatching(); //START OBSERVING