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;
  }
  
 
 
}