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android 截屏监听 详解Android截屏事件监听

王三的猫阿德 人气:5
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1. 前言

Android系统没有直接对截屏事件监听的接口,也没有广播,只能自己动手来丰衣足食,一般有三种方法。

由于厂商自定义Android系统的多样性,再加上快捷键的不同以及第三方应用,监听截屏快捷键这事基本不靠谱,可以直接忽略。

本文使用的测试手机,一加2(One Plus 2)。

2. FileObserver

添加权限:

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

代码示例:

public class ScreenshotActivity extends AppCompatActivity {

  private final String TAG = "Screenshot";

  private static final String PATH = Environment.getExternalStorageDirectory() + File.separator 
      + Environment.DIRECTORY_PICTURES + File.separator + "Screenshots" + File.separator;

  protected void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_screenshot);

    mFileObserver = new CustomFileObserver(PATH);
  }

  @Override
  protected void onResume() {
    super.onResume();
    mFileObserver.startWatching();
    Log.d(TAG, PATH);
  }

  @Override
  protected void onStop() {
    super.onStop();
    mFileObserver.stopWatching();
  }

  /**
   * 目录监听器
   */
  private class CustomFileObserver extends FileObserver {

    private String mPath;

    public CustomFileObserver(String path) {
      super(path);
      this.mPath = path;
    }

    public CustomFileObserver(String path, int mask) {
      super(path, mask);
      this.mPath = path;
    }

    @Override
    public void onEvent(int event, String path) {
      Log.d(TAG, path + " " + event);
      // 监听到事件,做一些过滤去重处理操作
    }
  }
}

打印的日志:

一加2

D/Screenshot: Screenshot_2016-12-16-17-49-18.png 256
D/Screenshot: Screenshot_2016-12-16-17-49-18.png 32
D/Screenshot: Screenshot_2016-12-16-17-49-18.png 2
D/Screenshot: Screenshot_2016-12-16-17-49-18.png 2
D/Screenshot: Screenshot_2016-12-16-17-49-18.png 2
D/Screenshot: Screenshot_2016-12-16-17-49-18.png 2
D/Screenshot: Screenshot_2016-12-16-17-49-18.png 2
D/Screenshot: Screenshot_2016-12-16-17-49-18.png 2
D/Screenshot: Screenshot_2016-12-16-17-49-18.png 2
D/Screenshot: Screenshot_2016-12-16-17-49-18.png 2
D/Screenshot: Screenshot_2016-12-16-17-49-18.png 2
D/Screenshot: Screenshot_2016-12-16-17-49-18.png 2
D/Screenshot: Screenshot_2016-12-16-17-49-18.png 2
D/Screenshot: Screenshot_2016-12-16-17-49-18.png 2
D/Screenshot: Screenshot_2016-12-16-17-49-18.png 2
D/Screenshot: Screenshot_2016-12-16-17-49-18.png 2
D/Screenshot: Screenshot_2016-12-16-17-49-18.png 2
D/Screenshot: Screenshot_2016-12-16-17-49-18.png 8

三星 S4

D/Screenshot: Screenshot_2016-12-16-19-01-08.png 256
D/Screenshot: Screenshot_2016-12-16-19-01-08.png 32
D/Screenshot: Screenshot_2016-12-16-19-01-08.png 2
D/Screenshot: Screenshot_2016-12-16-19-01-08.png 2
D/Screenshot: Screenshot_2016-12-16-19-01-08.png 2
D/Screenshot: Screenshot_2016-12-16-19-01-08.png 2
D/Screenshot: Screenshot_2016-12-16-19-01-08.png 2
D/Screenshot: Screenshot_2016-12-16-19-01-08.png 2
D/Screenshot: Screenshot_2016-12-16-19-01-08.png 2
D/Screenshot: Screenshot_2016-12-16-19-01-08.png 2
D/Screenshot: Screenshot_2016-12-16-19-01-08.png 2
D/Screenshot: Screenshot_2016-12-16-19-01-08.png 2
D/Screenshot: Screenshot_2016-12-16-19-01-08.png 2
D/Screenshot: Screenshot_2016-12-16-19-01-08.png 2
D/Screenshot: Screenshot_2016-12-16-19-01-08.png 2
D/Screenshot: Screenshot_2016-12-16-19-01-08.png 2
D/Screenshot: Screenshot_2016-12-16-19-01-08.png 2
D/Screenshot: Screenshot_2016-12-16-19-01-08.png 2
D/Screenshot: Screenshot_2016-12-16-19-01-08.png 2
D/Screenshot: Screenshot_2016-12-16-19-01-08.png 2
D/Screenshot: Screenshot_2016-12-16-19-01-08.png 2
D/Screenshot: Screenshot_2016-12-16-19-01-08.png 8
D/Screenshot: Screenshot_2016-12-16-19-01-08.png 32
D/Screenshot: Screenshot_2016-12-16-19-01-08.png 16

可以通过指定构造函数中的mask,监听某一个事件。

类型 int值 说明
FileObserver.ACCESS 1 读取某个文件
FileObserver.MODIFY 2 向某个文件写入数据
FileObserver.ATTRIB 4 文件的属性被修改(权限/日期/拥有者)
FileObserver.CLOSE_WRITE 8 写入数据后关闭
FileObserver.CLOSE_NOWRITE 16 只读模式打开文件后关闭
FileObserver.OPEN 32 打开某个文件
FileObserver.MOVED_FROM 64 有文件或者文件夹从被监听的文件夹中移走
FileObserver.MOVED_TO 128 有文件或者文件夹移动到被监听的文件夹
FileObserver.CREATE 256 文件或者文件夹被创建
FileObserver.DELETE 512 文件被删除
FileObserver.DELETE_SELF 1024 被监听的文件或者目录被删除
FileObserver.MOVE_SELF 2048 被监听的文件或者目录被移走

几点注意事项:

基于第三点和第四点,这种方法并不能适用于所有的机型。

注意:如果自己写Demo没有收到事件,检查一下权限和监听的目录

3. ContentObserver

ContentObserver用来监听指定uri的所有资源变化,我们可以用它来监听图片资源变化情况,然后做过滤。

添加权限

<uses-permission android:name="MediaStore.Images.Media.INTERNAL_CONTENT_URI"/>
<uses-permission android:name="MediaStore.Images.Media.EXTERNAL_CONTENT_URI"/>

代码示例:

public class ScreenshotActivity extends AppCompatActivity {
  private static final String[] KEYWORDS = {
      "screenshot", "screen_shot", "screen-shot", "screen shot",
      "screencapture", "screen_capture", "screen-capture", "screen capture",
      "screencap", "screen_cap", "screen-cap", "screen cap"
  };

  /** 读取媒体数据库时需要读取的列 */
  private static final String[] MEDIA_PROJECTIONS = {
      MediaStore.Images.ImageColumns.DATA,
      MediaStore.Images.ImageColumns.DATE_TAKEN,
  };

  /** 内部存储器内容观察者 */
  private ContentObserver mInternalObserver;

  /** 外部存储器内容观察者 */
  private ContentObserver mExternalObserver;

  private HandlerThread mHandlerThread;
  private Handler mHandler;

  protected void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_screenshot);

    mHandlerThread = new HandlerThread("Screenshot_Observer");
    mHandlerThread.start();
    mHandler = new Handler(mHandlerThread.getLooper());

    // 初始化
    mInternalObserver = new MediaContentObserver(MediaStore.Images.Media.INTERNAL_CONTENT_URI, mHandler);
    mExternalObserver = new MediaContentObserver(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, mHandler);

    // 添加监听
    this.getContentResolver().registerContentObserver(
      MediaStore.Images.Media.INTERNAL_CONTENT_URI,
      false,
      mInternalObserver
    );
    this.getContentResolver().registerContentObserver(
      MediaStore.Images.Media.EXTERNAL_CONTENT_URI,
      false,
      mExternalObserver
    );
  }

  protected void onDestroy() {
    super.onDestroy();
    // 注销监听
    this.getContentResolver().unregisterContentObserver(mInternalObserver);
    this.getContentResolver().unregisterContentObserver(mExternalObserver);
  }

  private void handleMediaContentChange(Uri contentUri) {
    Cursor cursor = null;
    try {
      // 数据改变时查询数据库中最后加入的一条数据
      cursor = this.getContentResolver().query(
          contentUri,
          MEDIA_PROJECTIONS,
          null,
          null,
          MediaStore.Images.ImageColumns.DATE_ADDED + " desc limit 1"
      );

      if (cursor == null) {
        return;
      }
      if (!cursor.moveToFirst()) {
        return;
      }

      // 获取各列的索引
      int dataIndex = cursor.getColumnIndex(MediaStore.Images.ImageColumns.DATA);
      int dateTakenIndex = cursor.getColumnIndex(MediaStore.Images.ImageColumns.DATE_TAKEN);

      // 获取行数据
      String data = cursor.getString(dataIndex);
      long dateTaken = cursor.getLong(dateTakenIndex);

      // 处理获取到的第一行数据
      handleMediaRowData(data, dateTaken);

    } catch (Exception e) {
      e.printStackTrace();

    } finally {
      if (cursor != null && !cursor.isClosed()) {
        cursor.close();
      }
    }
  }

  /**
   * 处理监听到的资源
   */
  private void handleMediaRowData(String data, long dateTaken) {
    if (checkScreenShot(data, dateTaken)) {
      Log.d(TAG, data + " " + dateTaken);
    } else {
      Log.d(TAG, "Not screenshot event");
    }
  }

  /**
   * 判断是否是截屏
   */
  private boolean checkScreenShot(String data, long dateTaken) {

    data = data.toLowerCase();
    // 判断图片路径是否含有指定的关键字之一, 如果有, 则认为当前截屏了
    for (String keyWork : KEYWORDS) {
      if (data.contains(keyWork)) {
        return true;
      }
    }
    return false;
  }

  /**
   * 媒体内容观察者(观察媒体数据库的改变)
   */
  private class MediaContentObserver extends ContentObserver {

    private Uri mContentUri;

    public MediaContentObserver(Uri contentUri, Handler handler) {
      super(handler);
      mContentUri = contentUri;
    }

    @Override
    public void onChange(boolean selfChange) {
      super.onChange(selfChange);
      Log.d(TAG, mContentUri.toString());
      handleMediaContentChange(mContentUri);
    }
  }
}

日志:

D/Screenshot: content://media/external/images/media
D/Screenshot: /storage/emulated/0/Pictures/Screenshots/Screenshot_2016-12-19-11-24-02.png 1482117842287

注意事项:

  1. ContentObserver会监听到所有图片资源的变化情况,要做好去重过滤工作
  2. 根据uri去读取ContentProvider内容时候,记得关闭cursor,防止内存泄漏
  3. 关键字可扩展,大大增加的监听的范围,比FileObserver好用多了,但是去重过滤会比FileObserver复杂一些。

4. 总结

目前这是在网上搜索到的关于截屏监听方法的总结,如果大家还有什么比较好的监听方法,欢迎分享。

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