在Android上使用ZXing识别条形码/二维码

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。