在Android上使用ZXing识别条形码/二维码

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。