如何使用Android Camera2 API捕获单个图像？

我正在使用Android Camera2 API捕获和处理图像。图像处理是对成功捕获的响应。我遇到的问题是相机捕获了2张图像，我无法更改Camera2Basic示例中的代码以确保仅捕获单个图像。可以通过向该ImageSaver.run()方法中的方法添加日志记录代码来证明该问题。Camera2BasicFragment.java

public void run() {
    Log.d("Camera2", "Saving image");
    ByteBuffer buffer = mImage.getPlanes()[0].getBuffer();
    ...
}

编辑-经过进一步调查后，问题似乎出在该示例的实现中，而不是API的基本要求。在示例中，以下代码跟踪摄像机的状态变化，

 private void process(CaptureResult result) {
        switch (mState) {
            case STATE_PREVIEW: {
                // We have nothing to do when the camera preview is working normally.
                break;
            }
            case STATE_WAITING_LOCK: {
                int afState = result.get(CaptureResult.CONTROL_AF_STATE);
                if (CaptureResult.CONTROL_AF_STATE_FOCUSED_LOCKED == afState ||
                        CaptureResult.CONTROL_AF_STATE_NOT_FOCUSED_LOCKED == afState) {
                    // CONTROL_AE_STATE can be null on some devices
                    Integer aeState = result.get(CaptureResult.CONTROL_AE_STATE);
                    if (aeState == null ||
                            aeState == CaptureResult.CONTROL_AE_STATE_CONVERGED) {
                        mState = STATE_WAITING_NON_PRECAPTURE;
                        /** CAPTURE 1 */
                        captureStillPicture();
                    } else {
                        runPrecaptureSequence();
                    }
                }
                break;
            }
            case STATE_WAITING_PRECAPTURE: {
                ...
                break;
            }
            case STATE_WAITING_NON_PRECAPTURE: {
                // CONTROL_AE_STATE can be null on some devices
                Integer aeState = result.get(CaptureResult.CONTROL_AE_STATE);
                if (aeState == null || aeState != CaptureResult.CONTROL_AE_STATE_PRECAPTURE) {
                    mState = STATE_PICTURE_TAKEN;
                    /** CAPTURE 2 **/
                    captureStillPicture();
                }
                break;
            }
        }
    }

我已经验证了两次调用都会captureStillPicture导致生成图像并进行处理。我不太确定正确的状态转换应该是什么。

我正在使用Motorola Nexus 6