一、切换摄像头

在前后摄像头之间切换，首先需要关闭之前打开的摄像头，关闭preview，之后重新打开新的摄像头，重新打开preview。

public void switchCamera() {

if (mCameraId.equals(CAMERA_FRONT)) {

mCameraId = CAMERA_BACK;

closeCamera();

reopenCamera();

} else if (mCameraId.equals(CAMERA_BACK)) {

mCameraId = CAMERA_FRONT;

closeCamera();

reopenCamera();

}

}

关闭摄像头：

/**

* Closes the current {@link CameraDevice}.

*/

private void closeCamera() {

try {

mCameraOpenCloseLock.acquire();

synchronized (mCameraStateLock) {

// Reset state and clean up resources used by the camera.

// Note: After calling this, the ImageReaders will be closed after any background

// tasks saving Images from these readers have been completed.

mPendingUserCaptures = 0;

mState = STATE_CLOSED;

if (null != mCaptureSession) {

mCaptureSession.close();

mCaptureSession = null;

}

if (null != mCameraDevice) {

mCameraDevice.close();

mCameraDevice = null;

}

if (null != mJpegImageReader) {

mJpegImageReader.close();

mJpegImageReader = null;

}

if (null != mRawImageReader) {

mRawImageReader.close();

mRawImageReader = null;

}

}

} catch (InterruptedException e) {

throw new RuntimeException("Interrupted while trying to lock camera closing.", e);

} finally {

mCameraOpenCloseLock.release();

}

}

打开新的摄像头：

public void reopenCamera() {

if (mTextureView.isAvailable()) {

openCamera();

} else {

mTextureView.setSurfaceTextureListener(mSurfaceTextureListener);

}

}

如果TextureView是available的，那么直接调用openCamera()打开camera(openCamera()的代码参考之前的博客)；如果|TextureView是unavailable的，那么调用TextureView的setSurfaceTextureListener设置SurfaceTextureListener(参考上一篇博客)。

二、延时拍摄

要实现延时拍摄，核心是实现一个定时器。本例延时分为三种模式：3s延时，10s按时，无延时。可以在三种模式之中自有切换。

private void switchDelayState() {

switch (mDelayState) {

case 0:

mTimer.setImageResource(R.mipmap.ic_3s);

mDelayTime = 3 * 1000;

mDelayState = 1;

break;

case 1:

mTimer.setImageResource(R.mipmap.ic_10s);

mDelayTime = 10 * 1000;

mDelayState = 2;

break;

case 2:

mTimer.setImageResource(R.mipmap.timer);

mDelayTime = 0;

mDelayState = 0;

break;

default:

break;

}

}

变量mDelayTime和mDelaySate的定义：

/*

* Delay state, 0 represents no delay, 1 represents 3s delay, while 2 represents 10s delay

*/

private short mDelayState = 0; // Timer

private short mDelayTime;

当拍摄按钮被点击时：

@Override

public void onClick(View view) {

switch (view.getId()) {

case R.id.capture: {

if (mDelayState == 0) {

takePicture();

} else {

new CountDownTimer(mDelayTime, TIME_INTERVAL) {

@Override

public void onTick(long millisUntilFinished) {

mTimeText.setVisibility(View.VISIBLE);

mTimeText.setText("" + millisUntilFinished / TIME_INTERVAL);

}

@Override

public void onFinish() {

mTimeText.setVisibility(View.GONE);

takePicture();

}

}.start();

}

break;

}

但有3s或10s延时的时候，利用CountDownTimer实现倒计时并每隔一秒更新剩余时间提示，到时候执行拍照功能。

三、切换闪光模式

支持自动，强制，禁止闪光。与闪光模式有关的属性是CaptureRequest.CONTROL_AE_MODE和CaptureRequest.FLASH_MODE。 如果要使用FLASH_MODE属相，闪光灯必须可用，并且，CONTROL_AE_MODE必须设置为on或off，否则，自动曝光属性的ON_AUTO_FLASH,ON_ALWAYS_FLASH,

ON_AUTO_FLASH_REDEYE将会覆盖FLASH_MODE的设置。

private void switchFlashMode() {

switch (mFlashMode) {

case 0:

mFlashMode = 1;

mFlashBtn.setImageResource(R.mipmap.flash_auto);

mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH);

try {

mCaptureSession.setRepeatingRequest(

mPreviewRequestBuilder.build(),

mPreCaptureCallback, mBackgroundHandler);

} catch (CameraAccessException e) {

e.printStackTrace();

return;

}

break;

case 1:

mFlashMode = 2;

mFlashBtn.setImageResource(R.mipmap.flash_on);

mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON_ALWAYS_FLASH);

try {

mCaptureSession.setRepeatingRequest(

mPreviewRequestBuilder.build(),

mPreCaptureCallback, mBackgroundHandler);

} catch (CameraAccessException e) {

e.printStackTrace();

return;

}

break;

case 2:

mFlashMode = 0;

mFlashBtn.setImageResource(R.mipmap.flash_off);

mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON);

mPreviewRequestBuilder.set(CaptureRequest.FLASH_MODE, CaptureRequest.FLASH_MODE_OFF);

try {

mCaptureSession.setRepeatingRequest(

mPreviewRequestBuilder.build(),

mPreCaptureCallback, mBackgroundHandler);

} catch (CameraAccessException e) {

e.printStackTrace();

return;

}

break;

}

}

在takePicture()之前，需要再次设置：

private void setFlashMode() {

switch (mFlashMode) {

case 0:

mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON);

mPreviewRequestBuilder.set(CaptureRequest.FLASH_MODE, CaptureRequest.FLASH_MODE_OFF);

break;

case 1:

mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH);

break;

case 2:

mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON_ALWAYS_FLASH);

break;

}

}

代码参考：https://github.com/gengqifu/361Camera，欢迎fork/star。