屏幕截图检测

使用Android的MediaProjection API获取屏幕内容并与系统截图进行比较

Android系统提供了MediaProjection API，可以获取屏幕内容并进行处理。我们可以利用这个API来实现屏幕截图检测。具体的解决方案如下：

1. 获取MediaProjection对象

在Activity中使用startActivityForResult()方法启动MediaProjectionManager，获得一个MediaProjection对象。

//声明全局变量
private MediaProjectionManager mediaProjectionManager;
private MediaProjection mediaProjection;
// 省略其他代码
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    // 获取MediaProjectionManager对象
    mediaProjectionManager = (MediaProjectionManager) getSystemService(Context.MEDIA_PROJECTION_SERVICE);
    // 启动获取屏幕的Activity，等待用户授权
    startActivityForResult(mediaProjectionManager.createScreenCaptureIntent(), REQUEST_CODE);
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (requestCode == REQUEST_CODE && resultCode == RESULT_OK) {
        // 获取MediaProjection对象
        mediaProjection = mediaProjectionManager.getMediaProjection(resultCode, data);
    }
}

2. 获取屏幕内容

使用MediaProjection对象构建VirtualDisplay对象，将屏幕内容输出到一个Surface中。然后使用MediaCodec将Surface中的帧数据解码为Bitmap对象。

private Bitmap captureScreen() {
    try {
        // 创建VirtualDisplay对象
        VirtualDisplay virtualDisplay = mediaProjection.createVirtualDisplay("ScreenCapture",
                screenWidth, screenHeight, screenDensity,
                DisplayManager.VIRTUAL_DISPLAY_FLAG_AUTO_MIRROR,
                surface, null, null);
        // 创建MediaCodec对象
        MediaCodec mediaCodec = MediaCodec.createDecoderByType(MediaFormat.MIMETYPE_VIDEO_AVC);
        mediaCodec.configure(format, surface, null, 0);
        // 解码器启动
        mediaCodec.start();
        // 获取解码出的帧数据
        ByteBuffer[] inputBuffers = mediaCodec.getInputBuffers();
        ByteBuffer[] outputBuffers = mediaCodec.getOutputBuffers();
        while (true) {
            MediaCodec.BufferInfo bufferInfo = new MediaCodec.BufferInfo();
            int inputBufferIndex = mediaCodec.dequeueInputBuffer(10000);
            if (inputBufferIndex >= 0) {
                // 获取Surface中的帧数据
                Bitmap bitmap = getBitmapFromSurface();
                // 将帧数据作为输入数据提供给解码器
                ByteBuffer inputBuffer = inputBuffers[inputBufferIndex];
                inputBuffer.clear();
                inputBuffer.put(getNV21(bitmap.getWidth(), bitmap.getHeight(), bitmap));
                mediaCodec.queueInputBuffer(inputBufferIndex, 0, inputBuffer.position(), 0, 0);
            }
            int outputBufferIndex = mediaCodec.dequeueOutputBuffer(bufferInfo, 10000);
            if (outputBufferIndex >= 0) {
                // 获取解码后的帧数据
                ByteBuffer outputBuffer = outputBuffers[outputBufferIndex];
                Bitmap bitmap = null;
                if (outputBuffer != null) {
                    int width = bufferInfo.width;
                    int height = bufferInfo.height;
                    int bufferSize = width * height * 3 / 2;
                    byte[] buffer = new byte[bufferSize];
                    outputBuffer.get(buffer);
                    outputBuffer.clear();
                    bitmap = BitmapFactory.decodeByteArray(buffer, 0, buffer.length);
                }
                mediaCodec.releaseOutputBuffer(outputBufferIndex, false);
                if (bitmap != null) {
                    return bitmap;
                }
            } 
        }
    } catch (Exception e) {
        e.printStackTrace();