Android 二维码识别

导读：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。

        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：

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1<uses-permission android:name="android.permission.CAMERA"></uses-permission>

2<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE">

3</uses-permission>

4<uses-feature android:name="android.hardware.camera"/>

5<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：

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01 

02<?xml version="1.0"encoding="utf-8"?>

03<FrameLayout

04android:id="@+id/FrameLayout01"

05android:layout_width="fill_parent"

06android:layout_height="fill_parent"

07xmlns:android="http://schemas.android.com/apk/res/android">

08

09<SurfaceView

10android:layout_height="fill_parent"

11android:id="@+id/sfvCamera"

12android:layout_width="fill_parent">

13</SurfaceView>

14<RelativeLayout

15android:id="@+id/RelativeLayout01"

16android:layout_height="fill_parent"

17android:layout_width="fill_parent">

18<ImageView

19android:id="@+id/ImageView01"

20android:layout_height="100dip"

21android:layout_width="160dip">

22</ImageView>

23<View

24android:layout_centerVertical="true"

25android:layout_centerHorizontal="true"

26android:layout_width="300dip"

27android:background="#55FF6666"

28android:id="@+id/centerView"

29android:layout_height="180dip">

30</View>

31<TextView

32android:layout_centerHorizontal="true"

33android:layout_width="wrap_content"

34android:layout_below="@+id/centerView"

35android:layout_height="wrap_content"

36android:text="Scanning..."

37android:id="@+id/txtScanResult"

38android:textColor="#FF000000">

39</TextView>

40</RelativeLayout>

41</FrameLayout>

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

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01 

02package eoe.demo;

03

04import java.util.Timer;

05import java.util.TimerTask;

06import com.google.zxing.BinaryBitmap;

07import com.google.zxing.MultiFormatReader;

08import com.google.zxing.Result;

09import com.google.zxing.Android.PlanarYUVLuminanceSource;

10import com.google.zxing.common.HybridBinarizer;

11import android.app.Activity;

12import android.graphics.Bitmap;

13import android.hardware.Camera;

14import android.os.Bundle;

15import android.view.SurfaceView;

16import android.view.View;

17import android.widget.ImageView;

18import android.widget.TextView;

19

20public class testCamera extendsActivity {

21/** Called when the activity is first created. */

22private SurfaceView sfvCamera;

23private SFHCamera sfhCamera;

24private ImageView imgView;

25private View centerView;

26private TextView txtScanResult;

27private Timer mTimer;

28private MyTimerTask mTimerTask;

29// 按照标准HVGA

30final static int width =480;

31final static int height =320;

32int dstLeft, dstTop, dstWidth, dstHeight;

33@Override

34public void onCreate(Bundle savedInstanceState) {

35super.onCreate(savedInstanceState);

36setContentView(R.layout.main);

37this.setTitle("Android条码/二维码识别Demo-----hellogv");

38imgView = (ImageView) this.findViewById(R.id.ImageView01);

39centerView = (View) this.findViewById(R.id.centerView);

40sfvCamera = (SurfaceView) this.findViewById(R.id.sfvCamera);

41sfhCamera = newSFHCamera(sfvCamera.getHolder(), width, height,

42previewCallback);

43txtScanResult=(TextView)this.findViewById(R.id.txtScanResult);

44// 初始化定时器

45mTimer = newTimer();

46mTimerTask = newMyTimerTask();

47mTimer.schedule(mTimerTask, 0,80);

48}

49class MyTimerTask extends TimerTask {

50@Override

51public void run() {

52if (dstLeft == 0) {//只赋值一次

53dstLeft = centerView.getLeft() * width

54/ getWindowManager().getDefaultDisplay().getWidth();

55dstTop = centerView.getTop() * height

56/ getWindowManager().getDefaultDisplay().getHeight();

57dstWidth = (centerView.getRight() - centerView.getLeft())* width

58/ getWindowManager().getDefaultDisplay().getWidth();

59dstHeight = (centerView.getBottom() - centerView.getTop())* height

60/ getWindowManager().getDefaultDisplay().getHeight();

61}

62sfhCamera.AutoFocusAndPreviewCallback();

63}

64}

65/**

66* 自动对焦后输出图片

67*/

68private Camera.PreviewCallback previewCallback = newCamera.PreviewCallback() {

69@Override

70public void onPreviewFrame(byte[] data, Camera arg1) {

71//取得指定范围的帧的数据

72PlanarYUVLuminanceSource source = new PlanarYUVLuminanceSource(

73data, width, height, dstLeft, dstTop, dstWidth, dstHeight);

74//取得灰度图

75Bitmap mBitmap = source.renderCroppedGreyscaleBitmap();

76//显示灰度图

77imgView.setImageBitmap(mBitmap);

78BinaryBitmap bitmap = newBinaryBitmap(newHybridBinarizer(source));

79MultiFormatReader reader = newMultiFormatReader();

80try {

81Result result = reader.decode(bitmap);

82String strResult = "BarcodeFormat:"+ result.getBarcodeFormat().toString() + " text:"

83+ result.getText();

84txtScanResult.setText(strResult);

85} catch(Exception e) {

86txtScanResult.setText("Scanning");

87}

88}

89};

90}

        SFHCamera.java是Camera控制类，源码如下：

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01 

02package eoe.demo;

03

04import java.io.IOException;

05import android.graphics.PixelFormat;

06import android.hardware.Camera;

07import android.util.Log;

08import android.view.SurfaceHolder;

09

10public class SFHCamera implementsSurfaceHolder.Callback{

11private SurfaceHolder holder = null;

12private Camera mCamera;

13private int width,height;

14private Camera.PreviewCallback previewCallback;

15public SFHCamera(SurfaceHolder holder,int w,int h,Camera.PreviewCallback previewCallback) {

16this.holder = holder;

17this.holder.addCallback(this);

18this.holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

19width=w;

20height=h;

21this.previewCallback=previewCallback;

22}

23@Override

24public void surfaceChanged(SurfaceHolder arg0, intarg1, int arg2, int arg3) {

25Camera.Parameters parameters = mCamera.getParameters();

26parameters.setPreviewSize(width, height);//设置尺寸

27parameters.setPictureFormat(PixelFormat.JPEG);

28mCamera.setParameters(parameters);

29mCamera.startPreview();//开始预览

30Log.e("Camera","surfaceChanged");

31}

32@Override

33public void surfaceCreated(SurfaceHolder arg0) {

34mCamera = Camera.open();//启动服务

35try {

36mCamera.setPreviewDisplay(holder);//设置预览

37Log.e("Camera","surfaceCreated");

38} catch(IOException e) {

39mCamera.release();//释放

40mCamera = null;

41}

42}

43@Override

44public void surfaceDestroyed(SurfaceHolder arg0) {

45mCamera.setPreviewCallback(null);

46mCamera.stopPreview();//停止预览

47mCamera = null;

48Log.e("Camera","surfaceDestroyed");

49}

50/**

51* 自动对焦并回调Camera.PreviewCallback

52*/

53public void AutoFocusAndPreviewCallback()

54{

55if(mCamera!=null)

56mCamera.autoFocus(mAutoFocusCallBack);

57}

58/**

59* 自动对焦

60*/

61private Camera.AutoFocusCallback mAutoFocusCallBack = newCamera.AutoFocusCallback() {

62@Override

63public void onAutoFocus(booleansuccess, Camera camera) {

64if (success) { //对焦成功，回调Camera.PreviewCallback

65mCamera.setOneShotPreviewCallback(previewCallback);

66}

67}

68};

69}

        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。