实现Android手机摄像头的自动对焦

如何实现Android相机的自动对焦，而且是连续自动对焦的。当然直接调用系统相机就不用说了，那个很简单的。下面我们主要来看看如如何自己实现一个相机，并且实现自动连续对焦。

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;
    }
   
 
 
}