使用Camera API在Android上切換攝像頭

Question

Hello there我是Camera API的newbiew。我正在向我自己學習！我只是想切換我的相機後臺和前臺！ 我的設備有前後相機！ 我這樣做，如：

---

public class CameraFrag extends Fragment { 

//Variables 
private Camera mCamera; 
private CameraPreview mPreview; 
private ToggleButton flipCamera; 
//////////////////////////////////// 

public CameraFrag() { 
} 

@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
    //inflate the layout 
    View v = inflater.inflate(R.layout.frag, container, false); 

    flipCamera = (ToggleButton) v.findViewById(R.id.flipper); 

    // Create an instance of Camera 
    mCamera = getCameraInstance(); 

    // Create our Preview view and set it as the content of our activity. 
    mPreview = new CameraPreview(getContext(), mCamera); 
    FrameLayout preview = (FrameLayout) v.findViewById(R.id.camera_preview); 
    preview.addView(mPreview); 

    flipCamera.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() { 
     @Override 
     public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) { 
      // TODO Auto-generated method stub 
      try{ 
       mCamera.stopPreview(); 

       if(isChecked){ 
        mCamera=openFrontFacingCamera(); 
       } 
       else{ 
        mCamera=openBackFacingCamera(); 
       } 
       mCamera.startPreview(); 
      }catch(Exception exp){ 
       Log.i("#LOGTAG","EXCEPTION "+exp); 
      } 
     } 
    }); 

    return v; 
} 

private Camera openBackFacingCamera() { 
    int cameraCount = 0; 
    Camera cam = null; 
    Camera.CameraInfo cameraInfo = new Camera.CameraInfo(); 
    cameraCount = Camera.getNumberOfCameras(); 
    for (int camIdx = 0; camIdx < cameraCount; camIdx++) { 
     Camera.getCameraInfo(camIdx, cameraInfo); 
     if (cameraInfo.facing == Camera.CameraInfo.CAMERA_FACING_BACK) { 
      cam = Camera.open(camIdx); 
     } 
    } 

    return cam; 
} 

private Camera openFrontFacingCamera() { 
    int cameraCount = 0; 
    Camera cam = null; 
    Camera.CameraInfo cameraInfo = new Camera.CameraInfo(); 
    cameraCount = Camera.getNumberOfCameras(); 
    for (int camIdx = 0; camIdx < cameraCount; camIdx++) { 
     Camera.getCameraInfo(camIdx, cameraInfo); 
     if (cameraInfo.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) { 
      cam = Camera.open(camIdx); 
     } 
    } 

    return cam; 
} 

/** A safe way to get an instance of the Camera object. */ 
public static Camera getCameraInstance(){ 
    Camera c = null; 
    try { 
     c = Camera.open(); // attempt to get a Camera instance 
    } 
    catch (Exception e){ 
     // Camera is not available (in use or does not exist) 
    } 
    return c; // returns null if camera is unavailable 
} 

}

---

的問題是，它總是拋出異常如：

I /＃LOGTAG：EXCEPTION的Java。 lang.RuntimeException：無法連接到相機服務

---

，如果我用我的代碼爲：

   try{ 
       mCamera.stopPreview(); 
       mCamera.release(); 
       if(isChecked){ 
        mCamera=openFrontFacingCamera(); 
       } 
       else{ 
        mCamera=openBackFacingCamera(); 
       } 
       mCamera.startPreview(); 
      }catch(Exception exp){ 
       Log.i("#LOGTAG","EXCEPTION "+exp); 
      } 

我的預覽凍結，回來時，我點擊後退按鈕！

---

我在做什麼錯了？這是在相機之間切換的正確方法嗎？有人可以幫我嗎？

在此先感謝！

Answer 1

只需打開這樣所需的攝像機：

對於前置攝像頭：

c = Camera.open(Camera.CameraInfo.CAMERA_FACING_FRONT); 

對於相機背面：

c = Camera.open(Camera.CameraInfo.CAMERA_FACING_BACK); 

，並確保你總是釋放你的相機，當你完成或在您的片段的onPause方法使用以下代碼否則相機實例將永遠不會被釋放，甚至您的主相機應用程序將無法獲得它。

private void releaseCameraAndPreview() { 
    if (mCamera != null) { 
     mCamera.stopPreview(); 
     mCamera.release(); 
     mCamera = null; 
    } 
}