Question

以下是我在Android中启用Flashlight的代码。在Toast消息中，它返回以下参数：auto，on，off，torch。将参数设置为FLASH_MODE_TORCH后，火炬不能启用。我的清单权限是：

<uses-permission android:name="android.permission.CAMERA"></uses-permission>
    <permission android:name="android.permission.FLASHLIGHT"
       android:permissionGroup="android.permission-group.HARDWARE_CONTROLS"
       android:protectionLevel="normal"/>
    <uses-feature android:name="android.hardware.camera"></uses-feature>

我的代码：

 public class CameraFlashActivity extends Activity {
        /** Called when the activity is first created. */
        public Camera mCamera;
        Parameters cameraParameters;
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.main);
            boolean cameraPresnt = this.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA_FLASH);
           if( cameraPresnt == true)
           {
               Toast.makeText(getApplicationContext(),"Flash is there",10).show();
               if(mCamera==null)
               {

                 try {
                    mCamera = Camera.open();
                    mCamera.startPreview();
                 Toast.makeText(getApplicationContext(),"Camera is  present",10).show();
                  } catch (Exception e) {
                    Log.i("CameraFlashActivity", "Camera.open() failed: " + e.getMessage());
                  }
                   if(mCamera==null)
                   {
                       Toast.makeText(getApplicationContext(),"Camera object is null",10).show();
                   }
                   else
                   {
               cameraParameters = mCamera.getParameters();
               if(cameraParameters==null)
               {
                   Toast.makeText(getApplicationContext(),"No camera parameters",10).show();
               }
               else
               {
                   List<String> flashmodes = cameraParameters.getSupportedFlashModes();
                   String supportedFlashModes = cameraParameters.getFlashMode();
                   Toast.makeText(getApplicationContext(),flashmodes.toString(),10).show();
                   Toast.makeText(getApplicationContext(),supportedFlashModes,10).show();
                   cameraParameters.setFlashMode(Parameters.FLASH_MODE_ON);
                   mCamera.setParameters(cameraParameters);
                   String supportFlashModes = cameraParameters.getFlashMode();
                   Toast.makeText(getApplicationContext(),supportFlashModes,10).show();
                   Toast.makeText(getApplicationContext(),"Camera parameters are set on flash light",10).show();

               }
                   }
               }
               else
               {

               }
           }
           else
           {
               Toast.makeText(getApplicationContext(),"Flash is not  there",10).show();
           }
        }
        public void onDestroy() {
            super.onDestroy();
            if (mCamera != null) {
                cameraParameters.setFlashMode(Parameters.FLASH_MODE_TORCH);
                   mCamera.setParameters(cameraParameters);
                   mCamera.stopPreview();
              mCamera.release();
            }
            Log.i("cameraFlashLight", "onDestroy");
          }
    }

Answer 1

使用以下代码序列：

mCamera = Camera.open();
cameraParameters = mCamera.getParameters();
cameraParameters.setFlashMode(Parameters.FLASH_MODE_TORCH);
mCamera.setParameters(parameters);
mCamera.startPreview();

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