實現Android手機攝像頭的自動對焦

如何實現Android相機的自動對焦，而且是連續自動對焦的。當然直接調用系統相機就不用說了，那個很簡單的。下面我們主要來看看如如何自己實現一個相機，并且實現自動連續對焦。

代碼如下：

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){
         //實現自動對焦
            camera.autoFocus(new AutoFocusCallback() {
                @Override
    public void onAutoFocus(boolean success, Camera camera) {
                 if(success){
                  initCamera();//實現相機的參數初始化
                 camera.cancelAutoFocus();//只有加上了這一句，才會自動對焦。
                 }
                }

   });
        }

 });
  }
  //相機參數的初始化設置
      private void initCamera()
  {
        parameters=camera.getParameters();
        parameters.setPictureFormat(PixelFormat.JPEG);
        //parameters.setPictureSize(surfaceView.getWidth(), surfaceView.getHeight());  // 部分定制手機，無法正常識別該方法。
   parameters.setFlashMode(Parameters.FLASH_MODE_TORCH); 
   parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);//1連續對焦
   setDispaly(parameters,camera);
   camera.setParameters(parameters);
   camera.startPreview();
   camera.cancelAutoFocus();// 2如果要實現連續的自動對焦，這一句必須加上

  }

      //控制圖像的正確顯示方向
      private void setDispaly(Camera.Parameters parameters,Camera camera)
      {
      if (Integer.parseInt(Build.VERSION.SDK) >= 8){
    setDisplayOrientation(camera,90);
   }
  else{
    parameters.setRotation(90);
   }

      }   

      //實現的圖像的正確顯示
      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", "圖像出錯");
   }
      }


    @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;
    }



}