在Android上使用ZXing识别条形码/二维码

本文来自http://blog.youkuaiyun.com/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。