Android studio Camera2实现的详细流程

前提

TextureView.SurfaceTextureListener是一个接口，用于监听TextureView中的SurfaceTexture的状态更改。在使用相机时，您可以使用TextureView来显示相机预览。通过实现SurfaceTextureListener接口，您可以在SurfaceTexture准备好时开始相机预览，并在SurfaceTexture销毁时停止预览。

注意: 必须是在 onSurfaceTextureAvailable 准备好后，才可开启相机

• 接口如下：
• （案例代码中是以implements TextureView.SurfaceTextureListener这种形式实现）

TextureView textureView = findViewById(R.id.texture_view);
textureView.setSurfaceTextureListener(new TextureView.SurfaceTextureListener() {
    @Override
    public void onSurfaceTextureAvailable(SurfaceTexture surfaceTexture, int width, int height) {
        // Open camera and start preview
    }

    @Override
    public void onSurfaceTextureSizeChanged(SurfaceTexture surfaceTexture, int width, int height) {
        // Handle texture size change if necessary
    }

    @Override
    public boolean onSurfaceTextureDestroyed(SurfaceTexture surfaceTexture) {
        // Stop camera preview and release camera
        return true;
    }

    @Override
    public void onSurfaceTextureUpdated(SurfaceTexture surfaceTexture) {
        // Handle surface texture update if necessary
    }
});

一、获取CameraManager实例

   CameraManager manager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);

二、获取可用的相机列表

   String[] cameraIds = manager.getCameraIdList();

三、选择一个相机并打开它

   String cameraId = cameraIds[0];
   manager.openCamera(cameraId, new CameraDevice.StateCallback() {
       @Override
       public void onOpened(CameraDevice camera) {
           // 相机已经打开，可以进行后续操作
       }

       @Override
       public void onDisconnected(CameraDevice camera) {
           // 相机断开连接，需要释放资源
           camera.close();
       }

       @Override
       public void onError(CameraDevice camera, int error) {
           // 相机打开出错，需要释放资源
           camera.close();
       }
   }, null);

四、创建一个CaptureRequest.Builder对象

   CaptureRequest.Builder builder = camera.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);

五、设置CaptureRequest.Builder对象的参数

   builder.set(CaptureRequest.CONTROL_MODE, CameraMetadata.CONTROL_MODE_AUTO);

六、创建一个CaptureSession对象

   camera.createCaptureSession(Arrays.asList(surface), new CameraCaptureSession.StateCallback() {
       @Override
       public void onConfigured(CameraCaptureSession session) {
           // CaptureSession已经创建，可以进行后续操作
       }

       @Override
       public void onConfigureFailed(CameraCaptureSession session) {
           // CaptureSession创建失败，需要释放资源
           camera.close();
       }
   }, null);

七、开始预览

   session.setRepeatingRequest(builder.build(), null, null);

代码示例

必须是动态获取权限后才能开启预览文章来源地址https://www.toymoban.com/news/detail-451299.html

• xml布局

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextureView
        android:id="@+id/texture_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
    
</RelativeLayout>

• 处理

public class MainActivity extends AppCompatActivity implements  TextureView.SurfaceTextureListener{

    private String[] cameraIds;
    private  String cameraId;
    private CameraManager cameraManager;//从系统服务中获取相机管理器
    private TextureView textureView;
    private CameraDevice mCameraDevice;
    private CameraCaptureSession cameraCaptureSession;
    private CaptureRequest.Builder builder = null;

    private static final int ACTION_REQUEST_PERMISSIONS = 0x001;
    /**
     * 所需的所有权限信息
     */
    private static final String[] NEEDED_PERMISSIONS = new String[]{
            Manifest.permission.CAMERA,//相机
    };


    @SuppressLint({"MissingPermission", "MissingInflatedId"})
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //权限检查
        if (!checkPermissions(NEEDED_PERMISSIONS)) {
            ActivityCompat.requestPermissions(this, NEEDED_PERMISSIONS,
                    ACTION_REQUEST_PERMISSIONS);
        }

        textureView=findViewById(R.id.texture_view);
        textureView.setSurfaceTextureListener(this);//设置布局
    }

    /**
     * 权限检查
     * @param neededPermissions 需要的权限
     * @return 是否全部被允许
     */
    protected boolean checkPermissions(String[] neededPermissions) {
        if (neededPermissions == null || neededPermissions.length == 0) {
            return true;
        }
        boolean allGranted = true;
        for (String neededPermission : neededPermissions) {
            allGranted &= ContextCompat.checkSelfPermission(this, neededPermission) == PackageManager.PERMISSION_GRANTED;
        }
        return allGranted;
    }


    @Override
    public void onSurfaceTextureAvailable(@NonNull SurfaceTexture surfaceTexture, int i, int i1) {
        //布局初始化完成,打开相机
       if (checkPermissions(NEEDED_PERMISSIONS)) {
            openCamera2();
        }
    }

    @SuppressLint("MissingPermission")
    private void openCamera2(){
        //一、获取cameraManager
        cameraManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
        try {
            cameraIds = cameraManager.getCameraIdList();//获取摄像机id的集合
            cameraId = cameraIds[0];
            cameraManager.openCamera(cameraId,callback,null);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    CameraDevice.StateCallback callback=new CameraDevice.StateCallback() {
        @Override
        public void onOpened(@NonNull CameraDevice cameraDevice) {
            mCameraDevice = cameraDevice;
            createCameraPreviewSession();
        }
        @Override
        public void onDisconnected(@NonNull CameraDevice cameraDevice) {

        }

        @Override
        public void onError(@NonNull CameraDevice cameraDevice, int i) {

        }
    };

    private void createCameraPreviewSession() {
        try {
            SurfaceTexture surfaceTexture = textureView.getSurfaceTexture();
//            surfaceTexture.setDefaultBufferSize(textureView.getWidth(), textureView.getHeight());
            surfaceTexture.setDefaultBufferSize(640, 480);
//            surfaceTexture.setDefaultBufferSize(480,640 );
            Surface previewSurface = new Surface(surfaceTexture);
            builder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
            builder.addTarget(previewSurface);
            mCameraDevice.createCaptureSession(Arrays.asList(previewSurface), new CameraCaptureSession.StateCallback() {
                @Override
                public void onConfigured(CameraCaptureSession session) {
                    cameraCaptureSession = session;
                    try {
                        cameraCaptureSession.setRepeatingRequest(builder.build(), null, null);
                    } catch (CameraAccessException e) {
                        e.printStackTrace();
                    }
                }
                @Override
                public void onConfigureFailed(CameraCaptureSession session) {
                    Toast.makeText(MainActivity.this, "Failed to create camera capture session", Toast.LENGTH_SHORT).show();
                }
            }, null);
        } catch (CameraAccessException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        switch (requestCode) {
            case ACTION_REQUEST_PERMISSIONS: {
                // 如果请求被取消，结果数组将为空
                if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    // 授权成功，执行相关操作
                    //打开相机
                    openCamera2();
                } else {
                    // 授权失败，禁用相关功能或显示提示信息

                }
                return;
            }
            // 处理其他权限请求
        }
    }

    @Override
    public void onSurfaceTextureSizeChanged(@NonNull SurfaceTexture surfaceTexture, int i, int i1) {

    }

    @Override
    public boolean onSurfaceTextureDestroyed(@NonNull SurfaceTexture  surfaceTexture) {
        return false;
    }

    @Override
    public void onSurfaceTextureUpdated(@NonNull SurfaceTexture surfaceTexture) {

    }
    @Override
    protected void onResume() {
        super.onResume();
    }

}

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