当我的应用程序在前台时，是否可以拦截截屏事件

Question

当我的应用程序在前台时，是否可以拦截截屏事件（或为其创建监听器）？我想在音量下+电源键截屏时执行一些自己的代码。

Answer 1

不，抱歉，您无法控制屏幕截图。如果您的目标是阻止您的应用截取屏幕截图（例如，出于安全原因），请使用FLAG_SECURE：

public class FlagSecureTestActivity extends Activity {
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    getWindow().setFlags(LayoutParams.FLAG_SECURE,
                         LayoutParams.FLAG_SECURE);

    setContentView(R.layout.main);
  }
}

Answer 2

执行此任务的方法是在屏幕截图目录中添加一个文件观察器。在下面编写示例代码以观察文件路径 截图文件观察者 包 com.example.main;

import android.os.Environment;
import android.os.FileObserver;
import android.util.Log;

public class ScreenshotObserver extends FileObserver {
        private static final String PATH = Environment.getExternalStorageDirectory().toString() + "/Pictures/Screenshots";
        private static final String TAG = "ScreenshotObserver";

        private ScreenshotListener listener;
        private String mLastTakenPath;

        ScreenshotObserver(ScreenshotListener listener) {
            super(PATH);
            this.listener = listener;
            Log.d(TAG, PATH);
        }

        @Override
        public void onEvent(int event, String path) {
            Log.d(TAG, String.format("Detected new file added %s", path));
            if (path==null || event != FileObserver.CLOSE_WRITE)
                Log.d(TAG, "Don't care.");
            else if (mLastTakenPath!=null && path.equalsIgnoreCase(mLastTakenPath))
                Log.d(TAG, "This event has been observed before.");
            else {
                mLastTakenPath = path;
                listener.onScreenshotTaken(path);
                Log.d(TAG, "Send event to listener.");
            }
        }

        public void start() {
            super.startWatching();
            Log.d(TAG, "Start Watching.");
        }

        public void stop() {
            super.stopWatching();
            Log.d(TAG, "Stop Watching.");
        }
} 

实现文件观察器的活动

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;


public class MainActivity extends Activity implements ScreenshotListener{
    private ScreenshotObserver obs;

    @Override
    protected void onCreate( Bundle savedInstanceState ) {
        super.onCreate(savedInstanceState);

        obs = new ScreenshotObserver(this);
        obs.start();
        setContentView(R.layout.activity_main);
    }

    @Override
    public void onScreenshotTaken( String path ) {
        TextView t = (TextView)findViewById(R.id.monText);
        t.setText("Screenshot taken ! " + path);
    }
}