实现Android手机摄像头的自动对焦详解手机开发

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。

代码如下：

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){ 
         //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; 
    } 
    
  
  
}