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;

}

}