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我需要用Camera2 API连续拍照。它适用于高端设备（例如Nexus 5X），但在较慢的设备（例如三星Galaxy A3）上，预览会冻结。Android Camera2，连续拍照
的代码是有点长，所以我张贴只有最相关的部分：
方法调用，开始我的预览：
private void startPreview() {
SurfaceTexture texture = mTextureView.getSurfaceTexture();
if(texture != null) {
try {
// We configure the size of default buffer to be the size of camera preview we want.
texture.setDefaultBufferSize(mPreviewSize.getWidth(), mPreviewSize.getHeight());
// This is the output Surface we need to start preview.
Surface surface = new Surface(texture);
// We set up a CaptureRequest.Builder with the output Surface.
mPreviewRequestBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
mPreviewRequestBuilder.addTarget(surface);
// Here, we create a CameraCaptureSession for camera preview.
mCameraDevice.createCaptureSession(Arrays.asList(surface, mImageReader.getSurface()), new CameraCaptureSession.StateCallback() {
@Override
public void onConfigured(@NonNull CameraCaptureSession cameraCaptureSession) {
// If the camera is already closed, return:
if (mCameraDevice == null) { return; }
// When the session is ready, we start displaying the preview.
mCaptureSession = cameraCaptureSession;
// Auto focus should be continuous for camera preview.
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
mPreviewRequest = mPreviewRequestBuilder.build();
// Start the preview
try { mCaptureSession.setRepeatingRequest(mPreviewRequest, null, mPreviewBackgroundHandler); }
catch (CameraAccessException e) { e.printStackTrace(); }
}
@Override
public void onConfigureFailed(@NonNull CameraCaptureSession cameraCaptureSession) {
Log.e(TAG, "Configure failed");
}
}, null
);
}
catch (CameraAccessException e) { e.printStackTrace(); }
}
}
方法调用，用于拍摄照片：
private void takePicture() {
try {
CaptureRequest.Builder captureBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
captureBuilder.addTarget(mImageReader.getSurface());
mCaptureSession.capture(captureBuilder.build(), null, mCaptureBackgroundHandler);
}
catch (CameraAccessException e) { e.printStackTrace(); }
}
这里是我的ImageReader：
private final ImageReader.OnImageAvailableListener mOnImageAvailableListener = new ImageReader.OnImageAvailableListener() {
@Override
public void onImageAvailable(final ImageReader reader) {
mSaveBackgroundHandler.post(new Runnable() {
@Override
public void run() {
// Set the destination file:
File destination = new File(getExternalFilesDir(null), "image_" + mNumberOfImages + ".jpg");
mNumberOfImages++;
// Acquire the latest image:
Image image = reader.acquireLatestImage();
// Save the image:
ByteBuffer buffer = image.getPlanes()[0].getBuffer();
byte[] bytes = new byte[buffer.remaining()];
buffer.get(bytes);
FileOutputStream output = null;
try {
output = new FileOutputStream(destination);
output.write(bytes);
}
catch (IOException e) { e.printStackTrace(); }
finally {
image.close();
if (null != output) {
try { output.close(); }
catch (IOException e) { e.printStackTrace(); }
}
}
// Take a new picture if needed:
if(mIsTakingPictures) {
takePicture();
}
}
});
}
};
我有一个按钮，切换mIsTakingPictures布尔值，并进行第一次takePicture调用。
总括来说，我使用3个线程：
- 一个用于预览
- 一个用于捕获
- 一个将图像保存
可能是什么原因这个冻结？