<uses-permission android:name="android.permission.CAMERA" />

<?xml version="1.0" encoding="utf-8"?><FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/container" android:layout_width="match_parent" android:layout_height="match_parent" android:background="#000" tools:context=".MainActivity"></FrameLayout>•fragment_camera.xml<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".CameraFragment"> <com.lightweh.camera2preview.AutoFitTextureView android:id="@+id/textureView" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerVertical="true" android:layout_centerHorizontal="true" /></RelativeLayout>

public class AutoFitTextureView extends TextureView { private int mRatioWidth = 0; private int mRatioHeight = 0; public AutoFitTextureView(Context context) { this(context, null); } public AutoFitTextureView(Context context, AttributeSet attrs) { this(context, attrs, 0); } public AutoFitTextureView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); } public void setAspectRatio(int width, int height) { if (width < 0 || height < 0) { throw new IllegalArgumentException("Size cannot be negative."); } mRatioWidth = width; mRatioHeight = height; requestLayout(); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); int width = MeasureSpec.getSize(widthMeasureSpec); int height = MeasureSpec.getSize(heightMeasureSpec); if (0 == mRatioWidth || 0 == mRatioHeight) { setMeasuredDimension(width, height); } else { if (width < height * mRatioWidth / mRatioHeight) { setMeasuredDimension(width, width * mRatioHeight / mRatioWidth); } else { setMeasuredDimension(height * mRatioWidth / mRatioHeight, height); } } }}

public class MainActivity extends AppCompatActivity { private static final int REQUEST_PERMISSION = 1; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); if (hasPermission()) { if (null == savedInstanceState) { setFragment(); } } else { requestPermission(); } } @Override public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) { if (requestCode == REQUEST_PERMISSION) { if (grantResults.length == 1 && grantResults[0] == PackageManager.PERMISSION_GRANTED) { setFragment(); } else { requestPermission(); } } else { super.onRequestPermissionsResult(requestCode, permissions, grantResults); } } // 權(quán)限判斷，當(dāng)系統(tǒng)版本大于23時(shí)，才有必要判斷是否獲取權(quán)限 private boolean hasPermission() { if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) { return checkSelfPermission(Manifest.permission.CAMERA) == PackageManager.PERMISSION_GRANTED; } else { return true; } } // 請求相機(jī)權(quán)限 private void requestPermission() { if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) { if (shouldShowRequestPermissionRationale(Manifest.permission.CAMERA)) { Toast.makeText(MainActivity.this, "Camera permission are required for this demo", Toast.LENGTH_LONG).show(); } requestPermissions(new String[]{Manifest.permission.CAMERA}, REQUEST_PERMISSION); } } // 啟動(dòng)相機(jī)Fragment private void setFragment() { getSupportFragmentManager() .beginTransaction() .replace(R.id.container, CameraFragment.newInstance()) .commitNowAllowingStateLoss(); }}

@Overridepublic void onResume() { super.onResume(); startBackgroundThread(); // When the screen is turned off and turned back on, the SurfaceTexture is  // already available, and "onSurfaceTextureAvailable" will not be called. In  // that case, we can open a camera and start preview from here (otherwise, we  // wait until the surface is ready in the SurfaceTextureListener). if (mTextureView.isAvailable()) { openCamera(mTextureView.getWidth(), mTextureView.getHeight()); } else { mTextureView.setSurfaceTextureListener(mSurfaceTextureListener); }}private void startBackgroundThread() { mBackgroundThread = new HandlerThread("CameraBackground"); mBackgroundThread.start(); mBackgroundHandler = new Handler(mBackgroundThread.getLooper());}

private void openCamera(int width, int height) { if (ContextCompat.checkSelfPermission(getActivity(), Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) { return; } setUpCameraOutputs(width, height); configureTransform(width, height); Activity activity = getActivity(); CameraManager manager = (CameraManager) activity.getSystemService(Context.CAMERA_SERVICE); try { if (!mCameraOpenCloseLock.tryAcquire(2500, TimeUnit.MILLISECONDS)) { throw new RuntimeException("Time out waiting to lock camera opening."); } manager.openCamera(mCameraId, mStateCallback, mBackgroundHandler); } catch (CameraAccessException e) { e.printStackTrace(); } catch (InterruptedException e) { throw new RuntimeException("Interrupted while trying to lock camera opening.", e); }}

private final CameraDevice.StateCallback mStateCallback = new CameraDevice.StateCallback() { @Override public void onOpened(@NonNull CameraDevice cameraDevice) { mCameraOpenCloseLock.release(); mCameraDevice = cameraDevice; createCameraPreviewSession(); } @Override public void onDisconnected(@NonNull CameraDevice cameraDevice) { mCameraOpenCloseLock.release(); cameraDevice.close(); mCameraDevice = null; } @Override public void onError(@NonNull CameraDevice cameraDevice, int error) { mCameraOpenCloseLock.release(); cameraDevice.close(); mCameraDevice = null; Activity activity = getActivity(); if (null != activity) { activity.finish(); } }};

private void createCameraPreviewSession() { try { // 獲取 texture 實(shí)例 SurfaceTexture texture = mTextureView.getSurfaceTexture(); assert texture != null; // 設(shè)置 TextureView 緩沖區(qū)大小 texture.setDefaultBufferSize(mPreviewSize.getWidth(), mPreviewSize.getHeight()); // 獲取 Surface 顯示預(yù)覽數(shù)據(jù) Surface surface = new Surface(texture); // 構(gòu)建適合相機(jī)預(yù)覽的請求 mPreviewRequestBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW); // 設(shè)置 surface 作為預(yù)覽數(shù)據(jù)的顯示界面 mPreviewRequestBuilder.addTarget(surface); // 創(chuàng)建相機(jī)捕獲會(huì)話用于預(yù)覽 mCameraDevice.createCaptureSession(Arrays.asList(surface), new CameraCaptureSession.StateCallback() {  @Override  public void onConfigured(@NonNull CameraCaptureSession cameraCaptureSession) {  // 如果相機(jī)關(guān)閉則返回  if (null == mCameraDevice) {  return;  }  // 如果會(huì)話準(zhǔn)備好則開啟預(yù)覽  mCaptureSession = cameraCaptureSession;  try {  // 自動(dòng)對焦  mPreviewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE,   CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);  mPreviewRequest = mPreviewRequestBuilder.build();  // 設(shè)置反復(fù)捕獲數(shù)據(jù)的請求，預(yù)覽界面一直顯示畫面  mCaptureSession.setRepeatingRequest(mPreviewRequest,   null, mBackgroundHandler);  } catch (CameraAccessException e) {  e.printStackTrace();  }  }  @Override  public void onConfigureFailed(  @NonNull CameraCaptureSession cameraCaptureSession) {  showToast("Failed");  } }, null ); } catch (CameraAccessException e) { e.printStackTrace(); }}