Android 截屏事件监听

编程语言 12/26 阅读 370 views次 人气 0
摘要:

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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。

 

  • 利用FileObserver监听某个目录中资源变化情况

  • 利用ContentObserver监听全部资源的变化

  • 监听截屏快捷按键

 

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)。

 

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2. FileObserver

 

添加权限:

 

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

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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
        }
    }
}

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打印的日志:

 

一加2

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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

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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

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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:

 

  • 每一次截屏,有多个事件回调

  • 每一次截屏,不同的手机,事件回调可能有些不同,参考上述日志

  • 不同的手机,默认截屏图片储存的文件夹可能不同

  • FileObserver只能监听文件夹中子文件和子文件夹的变化情况,不能监听子文件夹内部的资源变化

  • 需要<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>权限,否则可能收不到事件

 

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

 

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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"/>

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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);
        }
    }
}

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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

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注意事项:

 

  • 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

  • 根据uri去读取ContentProvider内容时候,记得关闭cursor,防止内存泄漏

  • 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。

 

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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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