android MediaCodec 录屏实时时长功能实现完整代码

以下是一个简单的 Android MediaCodec 录屏实时时长功能的实现示例代码：

private MediaRecorder mMediaRecorder;
private MediaProjection mMediaProjection;
private VirtualDisplay mVirtualDisplay;
private boolean mIsRecording = false;
private long mStartTime;
private long mEndTime;

private static final int REQUEST_CODE_SCREEN_CAPTURE = 1;

private void startScreenRecording() {
    if (mIsRecording) {
        return;
    }

    mStartTime = System.currentTimeMillis();

    mMediaRecorder = new MediaRecorder();
    mMediaProjection = ((MediaProjectionManager) getSystemService(Context.MEDIA_PROJECTION_SERVICE))
            .getMediaProjection(Activity.RESULT_OK, mMediaProjectionCallback);
    DisplayMetrics metrics = getResources().getDisplayMetrics();
    int screenWidth = metrics.widthPixels;
    int screenHeight = metrics.heightPixels;
    int screenDensity = metrics.densityDpi;
    mMediaRecorder.setVideoSource(MediaRecorder.VideoSource.SURFACE);
    mMediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
    mMediaRecorder.setOutputFile(Environment.getExternalStorageDirectory() + "/screen_capture.mp4");
    mMediaRecorder.setVideoSize(screenWidth, screenHeight);
    mMediaRecorder.setVideoEncoder(MediaRecorder.VideoEncoder.H264);
    mMediaRecorder.setVideoEncodingBitRate(512 * 1000);
    mMediaRecorder.setVideoFrameRate(30);
    mMediaRecorder.prepare();
    mVirtualDisplay = mMediaProjection.createVirtualDisplay("ScreenCapture",
            screenWidth, screenHeight, screenDensity,
            DisplayManager.VIRTUAL_DISPLAY_FLAG_AUTO_MIRROR,
            mMediaRecorder.getSurface(), null, null);
    mMediaRecorder.start();
    mIsRecording = true;
}

private void stopScreenRecording() {
    if (!mIsRecording) {
        return;
    }

    mEndTime = System.currentTimeMillis();

    mMediaRecorder.stop();
    mMediaRecorder.reset();
    mMediaRecorder.release();
    mMediaProjection.stop();
    mVirtualDisplay.release();
    mIsRecording = false;

    long duration = mEndTime - mStartTime;
    Toast.makeText(this, "Screen recording stopped. Duration: " + duration + "ms", Toast.LENGTH_SHORT).show();
}

private MediaProjection.Callback mMediaProjectionCallback = new MediaProjection.Callback() {
    @Override
    public void onStop() {
        stopScreenRecording();
    }
};

private void requestScreenCapture() {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
        startActivityForResult(((MediaProjectionManager) getSystemService(Context.MEDIA_PROJECTION_SERVICE))
                        .createScreenCaptureIntent(),
                REQUEST_CODE_SCREEN_CAPTURE);
    }
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);

    if (requestCode == REQUEST_CODE_SCREEN_CAPTURE) {
        if (resultCode == Activity.RESULT_OK) {
            mMediaProjection = ((MediaProjectionManager) getSystemService(Context.MEDIA_PROJECTION_SERVICE))
                    .getMediaProjection(resultCode, data);
            startScreenRecording();
        } else {
            Toast.makeText(this, "Screen capture permission denied.", Toast.LENGTH_SHORT).show();
        }
    }
}

在这个示例中，我们使用 MediaRecorder 和 MediaProjection API 实现了录屏功能。当 startScreenRecording() 方法被调用时，它会创建一个 MediaRecorder 对象，并调用 MediaProjection API 来获取一个 VirtualDisplay 对象。然后，它会将 MediaRecorder 的输出设置为 VirtualDisplay 的 Surface，从而将屏幕内容录制到视频文件中。最后，它会在屏幕录制结束时停止 MediaRecorder 和 MediaProjection，并计算录制时间。

请注意，为了使用 MediaProjection API，您需要在 AndroidManifest.xml 文件中添加以下权限：

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.MEDIA_CONTENT_CONTROL" />

您还需要在您的 Activity 中处理 onActivityResult() 方法，以获取 MediaProjection 对象。

此外，由于 Android MediaCodec 的工作方式比较复杂，如果您需要更高级的录屏功能，建议使用第三方库，如 FFmpeg 或 AndroidFFmpeg。