public class SecondActivity extends Activity implements SurfaceHolder.Callback,
        PreviewCallback
{
    // 定义对象
    private SurfaceView mSurfaceview = null; // SurfaceView对象：(视图组件)视频显示
    private SurfaceHolder mSurfaceHolder = null; // SurfaceHolder对象：(抽象接口)SurfaceView支持类
    private Camera mCamera = null; // Camera对象，相机预览
    private String TAG = "SnapCamera";
    private boolean bIfPreview = false;
    private int mPreviewWidth;
    private int mPreviewHeight;
    Bitmap mBitmap = null;
 
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initSurfaceView();
    }
 
    // InitSurfaceView
    private void initSurfaceView()
    {
        mSurfaceview = (SurfaceView) this.findViewById(R.id.CameraView);
        mSurfaceHolder = mSurfaceview.getHolder(); // 绑定SurfaceView，取得SurfaceHolder对象
        mSurfaceHolder.addCallback(SecondActivity.this); // SurfaceHolder加入回调接口
        // mSurfaceHolder.setFixedSize(176, 144); // 预览大小設置
        mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);// 设置显示器类型，setType必须设置
    }
 
    /* 【2】【相机预览】 */
    private void initCamera()// surfaceChanged中调用
    {
        Log.i(TAG, "going into initCamera");
        if (bIfPreview)
        {
            mCamera.stopPreview();// stopCamera();
        }
        if (null != mCamera)
        {
            try
            {
                /* Camera Service settings */
                Camera.Parameters parameters = mCamera.getParameters();
                // parameters.setFlashMode("off"); // 无闪光灯
                parameters.setPictureFormat(PixelFormat.JPEG); // Sets the image format for picture 设定相片格式为JPEG，默认为NV21
                parameters.setPreviewFormat(PixelFormat.YCbCr_420_SP); // Sets the image format for preview picture，默认为NV21
 
                /*
                 * 【ImageFormat】JPEG/NV16(YCrCb format，used for
                 * Video)/NV21(YCrCb format，used for Image)/RGB_565/YUY2/YU12
                 */
 
                // 【调试】获取camera支持的PictrueSize，看看能否设置
                List<Size> pictureSizes = mCamera.getParameters()
                        .getSupportedPictureSizes();
                List<Size> previewSizes = mCamera.getParameters()
                        .getSupportedPreviewSizes();
                List<Integer> previewFormats = mCamera.getParameters()
                        .getSupportedPreviewFormats();
                List<Integer> previewFrameRates = mCamera.getParameters()
                        .getSupportedPreviewFrameRates();
                Log.i(TAG + "initCamera", "  support parameters is ");
                Size psize = null;
                for (int i = 0; i < pictureSizes.size(); i++)
                {
                    psize = pictureSizes.get(i);
                    Log.i(TAG + "initCamera", "PictrueSize,width: "
                            + psize.width + " height:" + psize.height);
                }
                for (int i = 0; i < previewSizes.size(); i++)
                {
                    psize = previewSizes.get(i);
                    Log.i(TAG + "initCamera", "PreviewSize,width: "
                            + psize.width + " height:" + psize.height);
                }
                Integer pf = null;
                for (int i = 0; i < previewFormats.size(); i++)
                {
                    pf = previewFormats.get(i);
                    Log.i(TAG + "initCamera", "PreviewFormats:" + pf);
                }
                Iterator<Integer> it = previewFrameRates.iterator();
                while (it.hasNext())
                {
                    Log.i(TAG + "initCamera", "PreviewFrameRates:" + it.next());
                }
 
                // 设置拍照和预览图片大小
                parameters.setPictureSize(640, 480); // 指定拍照图片的大小
                parameters.setPreviewSize(mPreviewWidth, mPreviewHeight); // 指定preview的大小
                // 这两个属性 如果这两个属性设置的和真实手机的不一样时，就会报错
 
                // 横竖屏镜头自动调整
                if (this.getResources().getConfiguration().orientation != Configuration.ORIENTATION_LANDSCAPE)
                {
                    parameters.set("orientation", "portrait"); //
                    parameters.set("rotation", 90); // 镜头角度转90度（默认摄像头是横拍）
                    mCamera.setDisplayOrientation(90); // 在2.2以上可以使用
                } else
                // 如果是横屏
                {
                    parameters.set("orientation", "landscape"); //
                    mCamera.setDisplayOrientation(0); // 在2.2以上可以使用
                }
 
                /* 视频流编码处理 */
                // 添加对视频流处理函数
 
                // 设定配置参数并开启预览
                mCamera.setParameters(parameters); // 将Camera.Parameters设定予Camera
                mCamera.startPreview(); // 打开预览画面
                bIfPreview = true;
 
                // 【调试】设置后的图片大小和预览大小以及帧率
                Camera.Size csize = mCamera.getParameters().getPreviewSize();
                mPreviewHeight = csize.height;
                mPreviewWidth = csize.width;
                Log.i(TAG + "initCamera", "After setting, PreviewSize:width: "
                        + csize.width + " height: " + csize.height);
                csize = mCamera.getParameters().getPictureSize();
                Log.i(TAG + "initCamera", "After setting, PictrueSize:width: "
                        + csize.width + " height: " + csize.height);
                Log.i(TAG + "initCamera", "After setting, PreviewFormat is "
                        + mCamera.getParameters().getPreviewFormat());
                Log.i(TAG + "initCamera", "After setting, PreviewFrameRate is "
                        + mCamera.getParameters().getPreviewFrameRate());
            } catch (Exception e)
            {
                e.printStackTrace();
            }
        }
    }
 
    /* 【SurfaceHolder.Callback 回调函数】 */
    public void surfaceCreated(SurfaceHolder holder)
    // SurfaceView启动时/初次实例化，预览界面被创建时，该方法被调用。
    {
        // TODO Auto-generated method stub
        mCamera = Camera.open();// 开启摄像头（2.3版本后支持多摄像头,需传入参数）
        try
        {
            Log.i(TAG, "SurfaceHolder.Callback：surface Created");
            
            mCamera.setPreviewDisplay(mSurfaceHolder);// set the surface to be
            // used for live preview
            mCamera.setPreviewCallback(SecondActivity.this);
 
        } catch (Exception ex)
        {
            if (null != mCamera)
            {
                mCamera.release();
                mCamera = null;
            }
            Log.i(TAG + "initCamera", ex.getMessage());
        }
    }
 
    public void surfaceChanged(SurfaceHolder holder, int format, int width,
            int height)
    // 当SurfaceView/预览界面的格式和大小发生改变时，该方法被调用
    {
        // TODO Auto-generated method stub
        Log.i(TAG, "SurfaceHolder.Callback: Surface Changed");
        mPreviewHeight = height;
        mPreviewWidth = width;
        initCamera();
    }
 
    public void surfaceDestroyed(SurfaceHolder holder)
    // SurfaceView销毁时，该方法被调用
    {
        // TODO Auto-generated method stub
        Log.i(TAG, "SurfaceHolder.Callback：Surface Destroyed");
        if (null != mCamera)
        {
            mCamera.setPreviewCallback(null); // ！！这个必须在前，不然退出出错
            mCamera.stopPreview();
            bIfPreview = false;
            mCamera.release();
            mCamera = null;
        }
    }
 
    @Override
    public void onPreviewFrame(byte[] data, Camera camera)
    {
        // TODO Auto-generated method stub
        Camera.Parameters parameters = camera.getParameters();
        int format = parameters.getPreviewFormat();
 
        if (mBitmap != null)
        {
            mBitmap.recycle();
            mBitmap = null;
        }
        // YUV formats require more conversion
        if (format == PixelFormat.YCbCr_420_SP
                || format == PixelFormat.YCbCr_422_I)
        {
            int w = 100/* parameters.getPreviewSize().width */;
            int h = 100/* parameters.getPreviewSize().height */;
 
            // Get the YuV image 由于此方法适用于android 2.2版本，所以此处不能用。
            // YuvImage yuv_image = new YuvImage(data, format, w, h, null);
            // // Convert YuV to Jpeg
            // Rect rect = new Rect(0, 0, w, h);
            // ByteArrayOutputStream output_stream = new
            // ByteArrayOutputStream();
            // yuv_image.compressToJpeg(rect, 100, output_stream);
            // // Convert from Jpeg to Bitmap
            // bitmap2 = BitmapFactory.decodeByteArray(output_stream
            // .toByteArray(), 0, output_stream.size());
 
            int[] i = new int[data.length];
            decodeYUV420SP(i, data, w, h);
            mBitmap = Bitmap.createBitmap(i, w, h, Bitmap.Config.RGB_565);
            // mBitmap = renderCroppedGreyscaleBitmap(data, w, h);
            // Log.e(TAG, "Image format is YUV:" + format);
        }
        // Jpeg and RGB565 are supported by BitmapFactory.decodeByteArray
        else if (format == PixelFormat.JPEG || format == PixelFormat.RGB_565)
        {
            // Log.e(TAG, "Image format is JPEG/RGB:" + format);
            mBitmap = BitmapFactory.decodeByteArray(data, 0, data.length);
        }
        
    }
 
    private void decodeYUV420SP(int[] rgb, byte[] yuv420sp, int width,
            int height)
    {
        // TODO Auto-generated method stub
        final int frameSize = width * height;
        for (int j = 0, yp = 0; j < height; j++)
        {
            int uvp = frameSize + (j >> 1) * width, u = 0, v = 0;
            for (int i = 0; i < width; i++, yp++)
            {
                int y = (0xff & ((int) yuv420sp[yp])) - 16;
                if (y < 0)
                    y = 0;
                if ((i & 1) == 0)
                {
                    v = (0xff & yuv420sp[uvp++]) - 128;
                    u = (0xff & yuv420sp[uvp++]) - 128;
                }
                int y1192 = 1192 * y;
                int r = (y1192 + 1634 * v);
                int g = (y1192 - 833 * v - 400 * u);
                int b = (y1192 + 2066 * u);
                if (r < 0)
                    r = 0;
                else if (r > 262143)
                    r = 262143;
                if (g < 0)
                    g = 0;
                else if (g > 262143)
                    g = 262143;
                if (b < 0)
                    b = 0;
                else if (b > 262143)
                    b = 262143;
                rgb[yp] = 0xff000000 | ((r << 6) & 0xff0000)
                        | ((g >> 2) & 0xff00) | ((b >> 10) & 0xff);
            }
        }
    }
}

private void getBestPreviewSize(Camera camera, Parameters parameters, SurfaceView cameraView)
    {
        int bestWidth=0;
        int bestHeight=0;
        List<Size> previewSizes=parameters.getSupportedPreviewSizes();
        if(previewSizes.size()>1)
        {
            Iterator<Size> cei=previewSizes.iterator();
            while(cei.hasNext())
            {
                Size aSize=cei.next();
                Log.v("snap shot","Checking "+aSize.width+"*"+aSize.height);
                if(aSize.width>bestWidth && aSize.width<=LARGETST_WIDTH 
                        && aSize.height >bestHeight
                        && aSize.height<=LARGETST_HEIGHT)
                {
                    bestWidth=aSize.width;
                    bestHeight=aSize.height;
                }
            }
            if(bestHeight!=0 && bestWidth!=0)
            {
                Log.v("snap shot","Using "+bestWidth+"*"+ bestHeight);
                parameters.setPreviewSize(bestWidth,bestHeight);
                cameraView.setLayoutParams(new LinearLayout.LayoutParams(bestWidth,bestHeight));
            }
        }
        camera.setParameters(parameters);
    }