Android相机预览发生失败到相机服务错误

Question

我想点击开始按钮，显示相机预览。

但不行。

我使用setPreviewDisplay startPreview

发生RuntimeException: Fail to connect to camera service

public class AndroidCamera extends Activity implements SurfaceHolder.Callback {

    private static Camera camera = null;
    private Camera camera;
    private static Camera camera2 = null;

    SurfaceView surfaceView;
    SurfaceView surfaceView2;

    SurfaceHolder surfaceHolder;
    SurfaceHolder surfaceHolder2;

    Button buttonStartCameraPreview, buttonStopCameraPreview;
    boolean previewing = false;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        buttonStartCameraPreview = (Button) findViewById(R.id.startcamerapreview);
        buttonStopCameraPreview = (Button) findViewById(R.id.stopcamerapreview);

        surfaceView = (SurfaceView) findViewById(R.id.surfaceview);

        surfaceHolder = surfaceView.getHolder();
        surfaceHolder.addCallback(this);
        surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

        buttonStartCameraPreview.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {

                if (!previewing) {
                    camera = Camera.open(0);

                    if (camera != null) {
                        try {
                            camera.setPreviewDisplay(surfaceHolder);

                            camera.startPreview();   //occur exception 

                            previewing = true;
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                }

            }
        });

    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {


    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {

    }


    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {

    }
}

我使用清单权限

<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera2" />
<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.autofocus"/>

感谢 请给我建议