小编use*_*794的帖子

我正在开发一款需要打开Galaxy Nexus设备手电筒的应用程序.我在这里提到了这个帖子

Galaxy Nexus上的LED手电筒可通过什么API控制？

public class TestCamera extends Activity implements SurfaceHolder.Callback{
Camera mCamera;
public static SurfaceView preview;
public static SurfaceHolder mHolder;
public void onCreate(Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    preview = (SurfaceView) findViewById(R.id.camSurface);
    mHolder = preview.getHolder();
    mCamera = Camera.open();
    try {
        mCamera.setPreviewDisplay(mHolder);
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    Button onLEDbtn = (Button) findViewById(R.id.onLED_btn);
    onLEDbtn.setOnClickListener(new OnClickListener(){

        public void onClick(View v) {
            // TODO Auto-generated method stub
            Toast.makeText(getApplicationContext(), "test", Toast.LENGTH_SHORT).show();
            Parameters params = mCamera.getParameters();
            params.setFlashMode(Parameters.FLASH_MODE_TORCH);
            mCamera.setParameters(params);      
            mCamera.startPreview();
        } …

我必须遵循代码,我只是想在我的Galaxy Nexus(4.0.2)中打开手电筒,但它没有这样做.

public class welcome extends Activity {

//MediaPlayer player;
/** Called when the activity is first created. */
@Override

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.welcome);

    Camera cam = Camera.open();     
    Parameters p = cam.getParameters();
    p.setFlashMode(Parameters.FLASH_MODE_TORCH);
    cam.setParameters(p);
    cam.startPreview();



}
}

我的清单文件:

<uses-sdk android:minSdkVersion="12" />
       <uses-permission android:name="android.permission.CAMERA" />
 <uses-feature android:name="android.hardware.camera" />

我想问一下,这是我的编码错误还是android版本问题？谢谢