1.Camera 2 的架构图：
camera2架构图
Camera2引用了管道的概念将安卓设备和摄像头之间联通起来，系统向摄像头发送Capture请求，而摄像头会返回CameraMetada。这一切都建立在CameraCaptureSession的会话中。
2.camera2拍照流程图：
camera2拍照流程图
3.具体实现步骤
3.1 申请权限 动态申请
Amdroidmanifest.xml文件中也需要输入以下代码
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>MainActivity.java 中
private static final String TAG = "预览";
private static final SparseIntArray ORIENTATION = new SparseIntArray();
static {
ORIENTATION.append(Surface.ROTATION_0,90);
ORIENTATION.append(Surface.ROTATION_90,0);
ORIENTATION.append(Surface.ROTATION_180,270);
ORIENTATION.append(Surface.ROTATION_270,180);
}
private String mCameraId; // 摄像头Id
private Size mPreviewSize; //获取分辨率
private ImageReader mImageReader; //图片阅读器
private CameraDevice mCameraDevice; //摄像头设备
private CameraCaptureSession mCaptureSession; //获取会话
private CaptureRequest mPreviewRequest; //获取请求
private CaptureRequest.Builder mPreviewRequestBuilder; //创建获取请求
private TextureView textureView; //预览视图
private Surface mPreviewSurface; //
private String[] permissions = {Manifest.permission.CAMERA,
Manifest.permission.READ_EXTERNAL_STORAGE,
Manifest.permission.WRITE_EXTERNAL_STORAGE };
private List<String> permissionList = new ArrayList();
// 第一步：获取权限
/**
* 获取拍照和读写权限
*/
private void getPermission() {
Log.i(TAG, " getPermission");
if (permissionList != null) {
permissionList.clear();
}
//版本判断 当手机系统大于23时,才有必要去判断权限是否获取
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
//权限是否已经 授权 GRANTED-授权 DINIED-拒绝
for (String permission : permissions) {
if (ContextCompat.checkSelfPermission(this, permission) != PackageManager.PERMISSION_GRANTED) {
permissionList.add(permission);
}
}
if (!permissionList.isEmpty()) {
ActivityCompat.requestPermissions(this, permissionList.toArray(new String[permissionList.size()]), 1000);
} else {
//表示全都授权了
textureView.setSurfaceTextureListener(textureListener);
}
}
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] mPermissions, @NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if (requestCode == 1000) {
//权限请求失败
if (grantResults.length > 0) {
//存放没授权的权限
List<String> deniedPermissions = new ArrayList<>();
for (int i = 0; i < grantResults.length; i++) {
int grantResult = grantResults[i];
String permission = permissions[i];
if (grantResult != PackageManager.PERMISSION_GRANTED) {
deniedPermissions.add(permission);
}
}
if (deniedPermissions.isEmpty()) {
//说明都授权了
openCamera();
} else {
getPermission();
}
}
}
}
3.2 在xml布局文件中
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextureView
android:id="@+id/textureView"
android:layout_width="match_parent"
android:layout_height="match_parent"
/>
<ImageButton
android:id="@+id/takePicture"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="@drawable/ic_baseline_camera_24"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginBottom="50dp"
/>
</RelativeLayout>3.3 写SurfaceView回调以及摄像头状态回调
// 1. SurfaceView状态回调
TextureView.SurfaceTextureListener textureListener = new TextureView.SurfaceTextureListener() {
@Override
public void onSurfaceTextureAvailable(@NonNull SurfaceTexture surfaceTexture, int width, int height) {
setupCamera(width,height);
configureTransform(width,height); //使配置改变
openCamera(); //打开相机
}
@Override
public void onSurfaceTextureSizeChanged(@NonNull SurfaceTexture surfaceTexture, int width, int height) {
configureTransform(width,height);
}
@Override
public boolean onSurfaceTextureDestroyed(@NonNull SurfaceTexture surfaceTexture) {
return false;
}
@Override
public void onSurfaceTextureUpdated(@NonNull SurfaceTexture surfaceTexture) {
}
};
// 2. 摄像头状态回调
private final CameraDevice.StateCallback stateCallback = new CameraDevice.StateCallback() {
//打开成功获取到camera设备
@Override
public void onOpened(@NonNull CameraDevice cameraDevice) {
mCameraDevice = cameraDevice;
//开启预览
startPreview();
}
//打开失败
@Override
public void onDisconnected(@NonNull CameraDevice cameraDevice) {
Toast.makeText(MainActivity.this, "摄像头设备连接失败", Toast.LENGTH_SHORT).show();
}
//打开错误
@Override
public void onError(@NonNull CameraDevice cameraDevice, int i) {
Toast.makeText(MainActivity.this, "摄像头设备连接出错", Toast.LENGTH_SHORT).show();
}
};3.4 设置相机
//设置摄像机
private void setupCamera(int width,int height){
//获取摄像头的管理者CameraManager
CameraManager manager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
try {
//遍历所有摄像头
for(String cameraId : manager.getCameraIdList()){
CameraCharacteristics characteristics = manager.getCameraCharacteristics(cameraId); //获取摄像机的特征
//默认打开后置 - 忽略前置 LENS（镜头）
if(characteristics.get(CameraCharacteristics.LENS_FACING) == CameraCharacteristics.LENS_FACING_FRONT) //如果是前置跳过
{
continue;
}
//获取StreamConfigurationMap,他是管理摄像头支持的所有输出格式
StreamConfigurationMap map = characteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
mPreviewSize = getOptimalSize(map.getOutputSizes(SurfaceTexture.class),width,height); //获取最佳的预览大小
int orientation = getResources().getConfiguration().orientation;
if(orientation== Configuration.ORIENTATION_LANDSCAPE){
textureView.setSurfaceTextureListener(textureListener);
}else {
textureView.setSurfaceTextureListener(textureListener);
}
mCameraId = cameraId;
break;
}
} catch (CameraAccessException e) {
e.printStackTrace();
}
}3.5 打开相机 关闭相机
private void openCamera(){
//获取摄像头的管理者 CameraManager
CameraManager manager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
//检查权限
try{
if(ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA)!= PackageManager.PERMISSION_GRANTED){
return;
}else{
manager.openCamera(mCameraId,stateCallback,null);
}
}catch (CameraAccessException e){
e.printStackTrace();
}
}
// 关闭相机
private void closeCamera(){
if(mCaptureSession != null){
mCaptureSession.close();
mCaptureSession = null;
}
if(mCameraDevice != null){
mCameraDevice.close();
mCameraDevice=null;
}
}
3.6 开启预览
private void startPreview(){
setupImageReader();
SurfaceTexture mSurfaceTexture = textureView.getSurfaceTexture();
//设置TextureView的缓冲区大小
mSurfaceTexture.setDefaultBufferSize(mPreviewSize.getWidth(),mPreviewSize.getHeight());
//获取Surface显示预览数据
mPreviewSurface = new Surface(mSurfaceTexture);
try {
getPreviewRequestBuilder();
//创建相机捕捉会话,第一个参数是捕获数据的输出Surface列表,第二个参数是CameraCaptureSession的状态回调接口,当他创建好后会回调onCconfigured方法
//第三个参数用来确定Callback在那个线程执行,null表示在当前线程执行
mCameraDevice.createCaptureSession(Arrays.asList(mPreviewSurface, mImageReader.getSurface()), new CameraCaptureSession.StateCallback() {
@Override
public void onConfigured(@NonNull CameraCaptureSession cameraCaptureSession) {
mCaptureSession = cameraCaptureSession;
repeatPreview();
}
@Override
public void onConfigureFailed(@NonNull CameraCaptureSession cameraCaptureSession) {
}
}, null);
}catch (CameraAccessException e){
e.printStackTrace();
}
}3.7 实现previewcallback
private CameraCaptureSession.CaptureCallback mPreviewCaptureCallback = new CameraCaptureSession.CaptureCallback() {
@Override
// 一旦捕获完成
public void onCaptureCompleted(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull TotalCaptureResult result) {
super.onCaptureCompleted(session, request, result);
}
};
private void repeatPreview(){
mPreviewRequestBuilder.setTag(TAG);
mPreviewRequest = mPreviewRequestBuilder.build();
//设置反复捕获数据的请求,这样预览界面就会一直有数据显示
try {
mCaptureSession.setRepeatingRequest(mPreviewRequest,mPreviewCaptureCallback,null);
}catch (CameraAccessException e)
{
e.printStackTrace();
}
}3.8 设置图片阅读器
private void setupImageReader(){
//前三个参数分别是需要的尺寸和格式,最后一个参数代表每次最多获取几帧数据
mImageReader = ImageReader.newInstance(mPreviewSize.getWidth(),mPreviewSize.getHeight(), ImageFormat.JPEG,1);
//监听ImageReader的事件,当有图像流数据可用时会回调onImageAvailable
mImageReader.setOnImageAvailableListener(new ImageReader.OnImageAvailableListener() {
@Override
public void onImageAvailable(ImageReader imageReader) {
Toast.makeText(MainActivity.this,"图片已保存",Toast.LENGTH_SHORT).show();
Image image = imageReader.acquireNextImage();
//开启线程一部保存图片
new Thread(new ImageSaver(image)).start();
}
},null);
}
//选择sizeMap中大于并且接近width和height的size
private Size getOptimalSize(Size[] sizeMap, int width,int height){
List<Size> sizeList = new ArrayList<>();
for(Size option:sizeMap){
if(width>height){
if(option.getWidth()>width && option.getHeight()>height){
sizeList.add(option);
}
}else {
if(option.getWidth()>height&&option.getHeight()>width){
sizeList.add(option);
}
}
}
if(sizeList.size()>0){
return Collections.min(sizeList, new Comparator<Size>() {
@Override
public int compare(Size size, Size t1) {
return Long.signum(size.getWidth()*size.getHeight()- t1.getWidth()*t1.getHeight());
}
});
}
return sizeMap[0];
}
//使配置转换
private void configureTransform(int viewWidth,int viewHeight){
if(textureView == null || mPreviewSize == null){
return;
}
int rotation = getWindowManager().getDefaultDisplay().getRotation();
Matrix matrix = new Matrix();
RectF viewRect = new RectF(0,0,viewWidth,viewHeight);
RectF bufferRect = new RectF(0,0,mPreviewSize.getHeight(),mPreviewSize.getWidth());
float centerX = viewRect.centerX();
float centerY = viewRect.centerY();
if(rotation == Surface.ROTATION_90 || rotation == Surface.ROTATION_90){
bufferRect.offset(centerX - bufferRect.centerX(),centerY - bufferRect.centerY());
matrix.setRectToRect(viewRect,bufferRect,Matrix.ScaleToFit.FILL);
float scale = Math.max((float) viewHeight/mPreviewSize.getHeight(),
(float) viewWidth/mPreviewSize.getWidth());
matrix.postScale(scale,scale,centerX,centerY);
matrix.postRotate(90*(rotation-2),centerX,centerY);
}else if(rotation == Surface.ROTATION_180){
matrix.postRotate(180,centerX,centerY);
}
textureView.setTransform(matrix);
}3.9 创建预览请求
//创建预览请求的Builder （TEMPLATE_PREVIEW表示预览请求）
private void getPreviewRequestBuilder(){
try {
mPreviewRequestBuilder =mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
}catch (CameraAccessException e){
e.printStackTrace();
}
//设置预览的显示图
mPreviewRequestBuilder.addTarget(mPreviewSurface);
MeteringRectangle[] meteringRectangles = mPreviewRequestBuilder.get(CaptureRequest.CONTROL_AE_REGIONS);
if(meteringRectangles != null && meteringRectangles.length > 0){
Toast.makeText(MainActivity.this,"PreviewRequestBuilder: AF_REGIONS=",Toast.LENGTH_SHORT).show();
}
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE,CaptureRequest.CONTROL_MODE_AUTO);
mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER,CaptureRequest.CONTROL_AF_TRIGGER_IDLE);
}3.10 拍照
// 拍照
private void takePhoto(){
try {
//首先创建拍照的请求 CaptureRequest
final CaptureRequest.Builder mCaptureBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
//获取屏幕方向
int rotation = getWindowManager().getDefaultDisplay().getRotation();
mCaptureBuilder.addTarget(mPreviewSurface);
mCaptureBuilder.addTarget(mImageReader.getSurface());
//设置拍照方向
mCaptureBuilder.set(CaptureRequest.JPEG_ORIENTATION,ORIENTATION.get(rotation));
//停止预览
mCaptureSession.stopRepeating();
//开始拍照,然后回调上面的接口重启预览,因为mCaptureBuilder设置ImageReader作为target,所以会自动回调ImageReader
// 的onImageAvailable()方法保存图片
CameraCaptureSession.CaptureCallback captureCallback = new CameraCaptureSession.CaptureCallback() {
@Override
public void onCaptureCompleted(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request,
@NonNull TotalCaptureResult result) {
super.onCaptureCompleted(session, request, result);
repeatPreview();
}
};
mCaptureSession.capture(mCaptureBuilder.build(),captureCallback,null);
}catch (CameraAccessException e){
e.printStackTrace();
}
}3.11 创建 子线程保存图片
// 第九步 创建子线程保存图片
public static class ImageSaver implements Runnable{
private Image mImage;
public ImageSaver(Image image) {
mImage = image;
}
@Override
public void run(){
ByteBuffer buffer = mImage.getPlanes()[0].getBuffer();
byte[] data =new byte[buffer.remaining()];
buffer.get(data);
File imageFile = new File(Environment.getExternalStorageDirectory()+"/DCIM/System.currentTimeMillis+myPicture.jpg");
FileOutputStream fos = null;
try {
fos = new FileOutputStream(imageFile);
fos.write(data,0, data.length);
}catch (IOException e){
e.printStackTrace();
}finally {
if(fos !=null){
try {
fos.close();
}catch (IOException e){
e.printStackTrace();
}
}
mImage.close(); // 必须关闭 不然拍第二章会报错
}
}
}3.12 活动的生命周期
//活动的创建
@Override
protected void onCreate(Bundle saveInstanceState){
super.onCreate(saveInstanceState);
setContentView(R.layout.activity_main);
textureView = findViewById(R.id.textureView);
textureView.setSurfaceTextureListener(textureListener);
getPermission();
findViewById(R.id.takePicture).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
takePhoto();
}
});
}
//onPause
@Override
protected void onPause(){
//closeCamera();
super.onPause();
}
protected void onResume(){
super.onResume();
// textureView.setSurfaceTextureListener(textureListener);
//openCamera();
}
protected void onDestroy(){
super.onDestroy();
closeCamera();
}这样就完成了 简单的预览拍照功能