Android如何在前台服务中使用glsurfaceView编码录制视频？并且不会因为界面退到后台而停止录制，请给出实例代码

好的，下面是一个使用 GLSurfaceView 进行视频编码和录制的示例代码，可以在前台服务中运行，并且不会因为界面退到后台而停止录制。

首先，需要在前台服务中创建一个 GLSurfaceView，并设置 Renderer。在 Renderer 的 onDrawFrame() 方法中，将 Surface 和纹理传递给编码器进行编码。同时，在 SurfaceTexture 上设置 OnFrameAvailableListener，当有新的帧可用时，会回调这个监听器，将最新的帧传递给编码器进行编码。编码器的回调函数中，将编码后的数据写入 Muxer。

以下是示例代码：

public class VideoEncoderService extends Service implements GLSurfaceView.Renderer, SurfaceTexture.OnFrameAvailableListener, MediaEncoder.MediaEncoderListener {

    private static final String TAG = "VideoEncoderService";

    private static final int FRAME_RATE = 30;
    private static final int I_FRAME_INTERVAL = 1;
    private static final int VIDEO_BITRATE = 2000000;
    private static final int AUDIO_BITRATE = 128000;

    private GLSurfaceView mGLSurfaceView;
    private SurfaceTexture mSurfaceTexture;
    private MediaCodec mVideoEncoder;
    private MediaMuxer mMuxer;
    private int mVideoTrackIndex;
    private boolean mMuxerStarted;
    private MediaEncoder mAudioEncoder;
    private MediaEncoder mVideoEncoderWrapper;

    private final Object mSyncObject = new Object();
    private boolean mFrameAvailable;
    private boolean mIsRecording;

    @Override
    public void onCreate() {
        super.onCreate();

        mGLSurfaceView = new GLSurfaceView(this);
        mGLSurfaceView.setEGLContextClientVersion(2);
        mGLSurfaceView.setRenderer(this);
        mGLSurfaceView.setRenderMode(GLSurfaceView.RENDERMODE_WHEN_DIRTY);

        WindowManager.LayoutParams params = new WindowManager.LayoutParams(
                WindowManager.LayoutParams.MATCH_PARENT,
                WindowManager.LayoutParams.MATCH_PARENT,
                WindowManager.LayoutParams.TYPE_APPLICATION_OVERLAY,
                WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE |
                WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
                PixelFormat.TRANSLUCENT);
        WindowManager wm = (WindowManager) getSystemService(WINDOW_SERVICE);
        wm.addView(mGLSurfaceView, params);
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        startRecording();
        return START_STICKY;
    }

    @Override
    public void onDestroy() {
        stopRecording();
        super.onDestroy();
    }

    private void startRecording() {
        synchronized (mSyncObject) {
            if (mIsRecording) {
                return;
            }

            try {
                String outputFile = getExternalFilesDir(null).getAbsolutePath() + "/output.mp4";
                mMuxer = new MediaMuxer(outputFile, MediaMuxer.OutputFormat.MUXER_OUTPUT_MPEG_4);

                mVideoEncoder = MediaCodec.createEncoderByType(MediaFormat.MIMETYPE_VIDEO_AVC);
                MediaFormat videoFormat = MediaFormat.createVideoFormat(MediaFormat.MIMETYPE_VIDEO_AVC, 720, 1280);
                videoFormat.setInteger(MediaFormat.KEY_BIT_RATE, VIDEO_BITRATE);
                videoFormat.setInteger(MediaFormat.KEY_FRAME_RATE, FRAME_RATE);
                videoFormat.setInteger(MediaFormat.KEY_COLOR_FORMAT, MediaCodecInfo.CodecCapabilities.COLOR_FormatSurface);
                videoFormat.setInteger(MediaFormat.KEY_I_FRAME_INTERVAL, I_FRAME_INTERVAL);
                mVideoEncoder.configure(videoFormat, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);
                Surface surface = mVideoEncoder.createInputSurface();
                mVideoEncoder.start();

                mVideoEncoderWrapper = new MediaEncoder(mVideoEncoder, this);

                mAudioEncoder = new AudioEncoder(AUDIO_BITRATE);
                mAudioEncoder.setMediaEncoderListener(this);

                mSurfaceTexture = new SurfaceTexture(1);
                mSurfaceTexture.setOnFrameAvailableListener(this);
                mGLSurfaceView.queueEvent(new Runnable() {
                    @Override
                    public void run() {
                        mSurfaceTexture.attachToGLContext(TEXTURE_ID);
                    }
                });

                mIsRecording = true;
            } catch (IOException e) {
                Log.e(TAG, "Failed to start recording", e);
                stopRecording();
            }
        }
    }

    private void stopRecording() {
        synchronized (mSyncObject) {
            if (!mIsRecording) {
                return;
            }

            mIsRecording = false;

            mAudioEncoder.stop();
            mAudioEncoder = null;

            mGLSurfaceView.queueEvent(new Runnable() {
                @Override
                public void run() {
                    mSurfaceTexture.detachFromGLContext();
                    mSurfaceTexture.release();
                }
            });

            mVideoEncoderWrapper.stop();
            mVideoEncoderWrapper = null;

            mVideoEncoder.stop();
            mVideoEncoder.release();
            mVideoEncoder = null;

            if (mMuxerStarted) {
                mMuxer.stop();
                mMuxer.release();
                mMuxer = null;
            }

            WindowManager wm = (WindowManager) getSystemService(WINDOW_SERVICE);
            wm.removeView(mGLSurfaceView);
        }
    }

    @Override
    public void onSurfaceCreated(GL10 gl, EGLConfig config) {
        GLES20.glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
        GLES20.glDisable(GLES20.GL_DEPTH_TEST);
    }

    @Override
    public void onSurfaceChanged(GL10 gl, int width, int height) {
        GLES20.glViewport(0, 0, width, height);
    }

    @Override
    public void onDrawFrame(GL10 gl) {
        GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT | GLES20.GL_DEPTH_BUFFER_BIT);

        synchronized (mSyncObject) {
            if (mFrameAvailable) {
                mFrameAvailable = false;
                mSurfaceTexture.updateTexImage();

                float[] mSTMatrix = new float[16];
                mSurfaceTexture.getTransformMatrix(mSTMatrix);

                mVideoEncoderWrapper.frameAvailableSoon(mSTMatrix);
            }
        }
    }

    @Override
    public void onFrameAvailable(SurfaceTexture surfaceTexture) {
        synchronized (mSyncObject) {
            mFrameAvailable = true;
            mGLSurfaceView.requestRender();
        }
    }

    @Override
    public void onMediaEncoderInitialized(MediaEncoder encoder) {
        synchronized (mSyncObject) {
            if (encoder instanceof AudioEncoder) {
                mAudioEncoder.start();
            } else if (encoder instanceof VideoEncoder) {
                mVideoTrackIndex = mMuxer.addTrack(encoder.getMediaFormat());
                mMuxer.start();
                mMuxerStarted = true;
            }
        }
    }

    @Override
    public void onMediaEncoderFrameEncoded(byte[] data, boolean isKeyFrame, long presentationTimeUs) {
        synchronized (mSyncObject) {
            if (mMuxerStarted) {
                ByteBuffer buffer = ByteBuffer.wrap(data);
                MediaCodec.BufferInfo bufferInfo = new MediaCodec.BufferInfo();
                bufferInfo.size = data.length;
                bufferInfo.presentationTimeUs = presentationTimeUs;
                bufferInfo.flags = isKeyFrame ? MediaCodec.BUFFER_FLAG_KEY_FRAME : 0;
                mMuxer.writeSampleData(mVideoTrackIndex, buffer, bufferInfo);
            }
        }
    }

    @Override
    public void onMediaEncoderStopped(MediaEncoder encoder) {
        synchronized (mSyncObject) {
            if (encoder instanceof AudioEncoder) {
                mAudioEncoder = null;
            } else if (encoder instanceof VideoEncoder) {
                mVideoTrackIndex = -1;
                mMuxerStarted = false;
            }
        }
    }
}

上面的代码中，我们在 onCreate() 方法中创建 GLSurfaceView 并添加到 WindowManager 中，然后在 onStartCommand() 方法中调用 startRecording() 方法开始录制视频。在 startRecording() 方法中，我们创建了一个 MediaCodec 编码器和一个 MediaMuxer Muxer，并将其关联起来。同时，我们还创建了一个 AudioEncoder 对象用于编码音频数据。我们还创建了一个 SurfaceTexture，并将其与 GLSurfaceView 关联起来。然后，我们在 onDrawFrame() 方法中获取最新的帧，并将其传递给编码器进行编码。在编码器的回调函数中，我们将编码后的数据写入 Muxer。最后，在 stopRecording() 方法中释放所有资源。

需要注意的是，由于涉及到多个线程之间的同步和通信，因此需要仔细处理线程安全问题。同时，为了避免被系统杀死，需要将服务设置为前台服务，并在通知栏中显示一个通知。