Android实现手机摄像头的自动对焦

public class MainActivity extends Activity { private SurfaceView surfaceView; private SurfaceHolder surfaceHolder; private boolean flag = false; private String fileUrl=""; Camera camera; Camera.Parameters parameters;  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);     setContentView(R.layout.activity_main);   surfaceView = (SurfaceView) findViewById(R.id.surfaceView1);   Button button=(Button) findViewById(R.id.takepicture);   surfaceHolder = surfaceView.getHolder();   surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);   surfaceHolder.setKeepScreenOn(true);   surfaceView.setFocusable(true);   surfaceView.setBackgroundColor(TRIM_MEMORY_BACKGROUND);   surfaceHolder.addCallback(new Callback() {   @Override public void surfaceDestroyed(SurfaceHolder holder) {  // TODO Auto-generated method stub  camera.stopPreview();  camera.release();  camera=null;   }   @Override public void surfaceCreated(SurfaceHolder holder) {  // TODO Auto-generated method stub  if(null==camera){   camera=Camera.open();      try {     camera.setPreviewDisplay(surfaceHolder);     initCamera();         camera.startPreview();  } catch (IOException e) {   // TODO Auto-generated catch block   e.printStackTrace();  }     }   }      @Override public void surfaceChanged(SurfaceHolder holder, int format, int width, int height){     //实现自动对焦      camera.autoFocus(new AutoFocusCallback() {        @Override  public void onAutoFocus(boolean success, Camera camera) {         if(success){         initCamera();//实现相机的参数初始化         camera.cancelAutoFocus();//只有加上了这一句，才会自动对焦。         }        }  });    } }); } //相机参数的初始化设置   private void initCamera() {    parameters=camera.getParameters();    parameters.setPictureFormat(PixelFormat.JPEG);    //parameters.setPictureSize(surfaceView.getWidth(), surfaceView.getHeight()); // 部分定制手机，无法正常识别该方法。  parameters.setFlashMode(Parameters.FLASH_MODE_TORCH);   parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);//1连续对焦  setDispaly(parameters,camera);  camera.setParameters(parameters);  camera.startPreview();  camera.cancelAutoFocus();// 2如果要实现连续的自动对焦，这一句必须加上   }    //控制图像的正确显示方向   private void setDispaly(Camera.Parameters parameters,Camera camera)   {   if (Integer.parseInt(Build.VERSION.SDK) >= 8){  setDisplayOrientation(camera,90);  } else{  parameters.setRotation(90);  }      }      //实现的图像的正确显示   private void setDisplayOrientation(Camera camera, int i) {   Method downPolymorphic; try{   downPolymorphic=camera.getClass().getMethod("setDisplayOrientation", new Class[]{int.class});     if(downPolymorphic!=null) {      downPolymorphic.invoke(camera, new Object[]{i});      }  }  catch(Exception e){  Log.e("Came_e", "图像出错");  }   }   @Override  public boolean onCreateOptionsMenu(Menu menu) {    // Inflate the menu; this adds items to the action bar if it is present.    getMenuInflater().inflate(R.menu.main, menu);        return true;  }    }