本文来自http://blog.csdn.net/hellogv/ ，引用必须注明出处！

越来越多的手机具备自动对焦的拍摄功能，这也意味着这些手机可以具备条码扫描的功能…….手机具备条码扫描的功能，可以优化购物流程，快速存储电子名片(二维码)等。

本文使用ZXing 1.6实现条码/二维码识别。ZXing是个很经典的条码/二维码识别的开源类库，long long ago，就有开发者在J2ME上使用ZXing了，不过要支持JSR-234规范(自动对焦)的手机才能发挥其威力，而目前已经有不少Android手机具备自动对焦的功能。

本文代码运行的结果如下，使用91手机助手截图时，无法截取SurfaceView的实时图像：

本文使用了ZXing1.6的core，即把/zxing-1.6/core/下的src复制覆盖工程的src；另外还要使用到/zxing-1.6/android/下的PlanarYUVLuminanceSource.java。

PS：/zxing-1.6/android/ 是BarcodeScanner的源码，本文程序相当于BarcodeScanner的精简版，只保留最基本的识别功能。

本文源码工程的下载地址如下：http://www.pudn.com/downloads349/sourcecode/comm/android/detail1521939.html

源码目录结果如下图，ChecksumException.java下面还有很多源文件，截图尚未列出：

本文例子必须要开摄像头和自动对焦的权限，不然启动时会报异常，所用的权限如下：

<uses-permission android:name=”android.permission.CAMERA”></uses-permission>
<uses-permission android:name=”android.permission.WRITE_EXTERNAL_STORAGE”></uses-permission>
<uses-feature android:name=”android.hardware.camera” />
<uses-feature android:name=”android.hardware.camera.autofocus” />

main.xml源码如下，main.xml必须要用到FrameLayout才能重叠控件实现“范围框”的效果：

<?xml version=”1.0″ encoding=”utf-8″?>
<FrameLayout android:id=”@+id/FrameLayout01″
android:layout_width=”fill_parent” android:layout_height=”fill_parent”
xmlns:android=”http://schemas.android.com/apk/res/android”>
<SurfaceView android:layout_height=”fill_parent”
android:id=”@+id/sfvCamera” android:layout_width=”fill_parent”></SurfaceView>
<RelativeLayout android:id=”@+id/RelativeLayout01″
android:layout_height=”fill_parent” android:layout_width=”fill_parent”>
<ImageView android:id=”@+id/ImageView01″
android:layout_height=”100dip” android:layout_width=”160dip”></ImageView>
<View android:layout_centerVertical=”true”
android:layout_centerHorizontal=”true” android:layout_width=”300dip”
android:background=”#55FF6666″ android:id=”@+id/centerView”
android:layout_height=”180dip”></View>
<TextView android:layout_centerHorizontal=”true”
android:layout_width=”wrap_content” android:layout_below=”@+id/centerView”
android:layout_height=”wrap_content” android:text=”Scanning…”
android:id=”@+id/txtScanResult” android:textColor=”#FF000000″></TextView>
</RelativeLayout>
</FrameLayout>

testCamera.java是主类，负责控制Camera和对图像做解码，源码如下：

package com.testCamera;
import java.util.Timer;
import java.util.TimerTask;
import com.google.zxing.BinaryBitmap;
import com.google.zxing.MultiFormatReader;
import com.google.zxing.Result;
import com.google.zxing.Android.PlanarYUVLuminanceSource;
import com.google.zxing.common.HybridBinarizer;
import android.app.Activity;
import android.graphics.Bitmap;
import android.hardware.Camera;
import android.os.Bundle;
import android.view.SurfaceView;
import android.view.View;
import android.widget.ImageView;
import android.widget.TextView;
public class testCamera extends Activity {
/** Called when the activity is first created. */
private SurfaceView sfvCamera;
private SFHCamera sfhCamera;
private ImageView imgView;
private View centerView;
private TextView txtScanResult;
private Timer mTimer;
private MyTimerTask mTimerTask;
// 按照标准HVGA
final static int width = 480;
final static int height = 320;
int dstLeft, dstTop, dstWidth, dstHeight;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
this.setTitle(“Android条码/二维码识别Demo—–hellogv”);
imgView = (ImageView) this.findViewById(R.id.ImageView01);
centerView = (View) this.findViewById(R.id.centerView);
sfvCamera = (SurfaceView) this.findViewById(R.id.sfvCamera);
sfhCamera = new SFHCamera(sfvCamera.getHolder(), width, height,
previewCallback);
txtScanResult=(TextView)this.findViewById(R.id.txtScanResult);
// 初始化定时器
mTimer = new Timer();
mTimerTask = new MyTimerTask();
mTimer.schedule(mTimerTask, 0, 80);
}

class MyTimerTask extends TimerTask {
@Override
public void run() {
if (dstLeft == 0) {//只赋值一次
dstLeft = centerView.getLeft() * width
/ getWindowManager().getDefaultDisplay().getWidth();
dstTop = centerView.getTop() * height
/ getWindowManager().getDefaultDisplay().getHeight();
dstWidth = (centerView.getRight() – centerView.getLeft())* width
/ getWindowManager().getDefaultDisplay().getWidth();
dstHeight = (centerView.getBottom() – centerView.getTop())* height
/ getWindowManager().getDefaultDisplay().getHeight();
}
sfhCamera.AutoFocusAndPreviewCallback();
}
}
/**
*  自动对焦后输出图片
*/
private Camera.PreviewCallback previewCallback = new Camera.PreviewCallback() {
@Override
public void onPreviewFrame(byte[] data, Camera arg1) {
//取得指定范围的帧的数据
PlanarYUVLuminanceSource source = new PlanarYUVLuminanceSource(
data, width, height, dstLeft, dstTop, dstWidth, dstHeight);
//取得灰度图
Bitmap mBitmap = source.renderCroppedGreyscaleBitmap();
//显示灰度图
imgView.setImageBitmap(mBitmap);
BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(source));
MultiFormatReader reader = new MultiFormatReader();
try {
Result result = reader.decode(bitmap);
String strResult = “BarcodeFormat:”
+ result.getBarcodeFormat().toString() + ”  text:”
+ result.getText();
txtScanResult.setText(strResult);
} catch (Exception e) {
txtScanResult.setText(“Scanning”);
}
}
};
}

SFHCamera.java是Camera控制类，源码如下：

package com.testCamera;
import java.io.IOException;
import android.graphics.PixelFormat;
import android.hardware.Camera;
import android.util.Log;
import android.view.SurfaceHolder;
public class SFHCamera implements SurfaceHolder.Callback{
private SurfaceHolder holder = null;
private Camera mCamera;
private int width,height;
private Camera.PreviewCallback previewCallback;

public SFHCamera(SurfaceHolder holder,int w,int h,Camera.PreviewCallback previewCallback) {
this.holder = holder;
this.holder.addCallback(this);
this.holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
width=w;
height=h;
this.previewCallback=previewCallback;
}

@Override
public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3) {
Camera.Parameters parameters = mCamera.getParameters();
parameters.setPreviewSize(width, height);//设置尺寸
parameters.setPictureFormat(PixelFormat.JPEG);
mCamera.setParameters(parameters);
mCamera.startPreview();//开始预览
Log.e(“Camera”,”surfaceChanged”);
}
@Override
public void surfaceCreated(SurfaceHolder arg0) {
mCamera = Camera.open();//启动服务
try {
mCamera.setPreviewDisplay(holder);//设置预览
Log.e(“Camera”,”surfaceCreated”);
} catch (IOException e) {
mCamera.release();//释放
mCamera = null;
}

}
@Override
public void surfaceDestroyed(SurfaceHolder arg0) {
mCamera.setPreviewCallback(null);
mCamera.stopPreview();//停止预览
mCamera = null;
Log.e(“Camera”,”surfaceDestroyed”);
}
/**
* 自动对焦并回调Camera.PreviewCallback
*/
public void AutoFocusAndPreviewCallback()
{
if(mCamera!=null)
mCamera.autoFocus(mAutoFocusCallBack);
}

/**
* 自动对焦
*/
private Camera.AutoFocusCallback mAutoFocusCallBack = new Camera.AutoFocusCallback() {

@Override
public void onAutoFocus(boolean success, Camera camera) {
if (success) {  //对焦成功，回调Camera.PreviewCallback
mCamera.setOneShotPreviewCallback(previewCallback);
}
}
};

}

其中testCamera.java的Camera.PreviewCallback previewCallback 是整个程序的逻辑核心，作为回调函数给SFHCamera.java的内部Camera类调用。