Android中调用摄像头并自动对焦拍照

首先需要在Manifest文件中添加以下内容：

<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.autofocus" android:required="false" />

程序获取摄像头使用以及自动对焦功能的使用权限。

CameraTestActivity.java

import android.app.Activity;
import android.os.Bundle;
import android.view.Window;
import android.view.WindowManager;

 public class CameraTestActivity extends Activity {
    @Override
    publicvoid onCreate(Bundle bundle) {
        super.onCreate(bundle);
        getWindow().clearFlags(WindowManager.LayoutParams.FLAG_FORCE_NOT_FULLSCREEN);
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);
        requestWindowFeature(Window.FEATURE_NO_TITLE);// 设置横屏模式以及全屏模式
        setContentView(new CameraView(this));//设置View
   }
}

　　CameraView.java

import java.io.FileOutputStream;

 import android.content.Context;
import android.hardware.Camera;
import android.os.Environment;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

 public class CameraView extends SurfaceView implements SurfaceHolder.Callback, Camera.PictureCallback {
    private SurfaceHolder holder;
    private Camera camera;
    privateboolean af;

     public CameraView(Context context) {//构造函数
      super(context);

         holder= getHolder();//生成Surface Holder
        holder.addCallback(this);

         holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);//指定Push Buffer
  }

     publicvoid surfaceCreated(SurfaceHolder holder) {//Surface生成事件的处理
       try {
            camera= Camera.open();//摄像头的初始化
           camera.setPreviewDisplay(holder);
        }catch (Exception e) {
        }
    }

     @Override
    publicvoid surfaceChanged(SurfaceHolder holder,int format,int width,int height) {//Surface改变事件的处理
        Camera.Parameters parameters= camera.getParameters();
        parameters.setPreviewSize(width, height);
        camera.setParameters(parameters);//设置参数
        camera.startPreview();//开始预览
  }

     publicvoid surfaceDestroyed(SurfaceHolder holder) {//Surface销毁时的处理
        camera.setPreviewCallback(null);
        camera.stopPreview();
        camera.release();
        camera= null;
    }

     @Override
    publicboolean onTouchEvent(MotionEvent event) {//屏幕触摸事件
       if (event.getAction()== MotionEvent.ACTION_DOWN) {//按下时自动对焦
            camera.autoFocus(null);
            af= true;
        }
       if (event.getAction()== MotionEvent.ACTION_UP&amp;&amp; af== true) {//放开后拍照
            camera.takePicture(null,null,this);
            af= false;
        }
       return true;
    }

     publicvoid onPictureTaken(byte[] data, Camera camera) {//拍摄完成后保存照片
       try {
            String path= Environment.getExternalStorageDirectory()+ "/test.jpg";
            data2file(data, path);
        }catch (Exception e) {
        }
        camera.startPreview();
    }

     privatevoid data2file(byte[] w, String fileName) throws Exception {//将二进制数据转换为文件的函数
        FileOutputStream out= null;
       try {
            out= new FileOutputStream(fileName);
            out.write(w);
            out.close();
        }catch (Exception e) {
           if (out!= null)
                out.close();
           throw e;
        }
    }

 }

　　说明：这是一个简单的示例程序。功能是使用自动对焦功能拍摄一张照片保存于SD卡根目录下。本例中许多参数都没有设置，可以根据具体需要进行适当的修改以满足特定要求。