Android 如何快速掃描條碼以及產生QR Code？

開發Android時常會需要應用到條碼讀取或是產生的功能，如果是自己寫一支條碼讀取和產生的功能的話會牽扯到許多相機應用、影像辨識以及條碼結構的問題需要去了解，費時費力，也不見得能做得出來。因此本篇文章將提供一個比較快速的方式，在Android App中實作出條碼掃描和產生的功能。

CodeScanner

CodeScanner是一個Java類別(Class)，可以快速地使用簡易條碼掃描器來協助App掃描或是讀取條碼。

程式如下：

package org.magiclen.code;

import java.util.List;
import java.util.Locale;

import android.app.Activity;
import android.app.AlertDialog;
import android.app.Fragment;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.content.pm.ResolveInfo;
import android.net.Uri;

/**
 * 條碼掃描
 * 
 * @author magiclen
 *
 */
public class CodeScanner {

	// -----類別常數-----
	private static final String SCAN_MODES = "SCAN_MODE";
	private static final String USE_CROP = "USE_CROP";
	private static final String SCAN_PREFIX = "SCAN_PREFIX";

	private static final String[] STRING_INSTALL_TITLE = new String[] { "Install Barcode Scanner", "安裝條碼掃描器" };
	private static final String[] STRING_INSTALL_CLOSE = new String[] { "Close", "關閉" };
	private static final String[] STRING_INSTALL_INSTALL = new String[] { "Install", "安裝" };
	private static final String[] STRING_INSTALL_MESSAGE = new String[] { "In order to scan barcode, you neet to install Easy Barcode Scanner first.", "為了能夠掃描條碼，您需要一個簡易條碼掃描器。" };
	private static final String[] STRING_URL_EASY_BARCODE_SCANNER = new String[] { "https://play.google.com/store/apps/details?id=org.magiclen.barcodescanner" };

	// -----類別列舉-----
	public static enum Mode {
		PRODUCT_MODE, SCAN_MODE, ONE_D_MODE, TWO_D_MODE, QR_CODE_MODE, DATA_MATRIX_MODE;
	}

	// -----類別介面-----
	public static interface CodeReaderListener {
		public void codeReadResult(final String type, final String data);
	}

	// -----類別變數-----
	private static boolean chinese = isChinese();

	// -----類別方法-----
	private static boolean isChinese() {
		final Locale locale = Locale.getDefault();
		return locale.equals(Locale.CHINESE) || locale.equals(Locale.SIMPLIFIED_CHINESE) || locale.equals(Locale.TRADITIONAL_CHINESE);
	}

	private static String getString(final String[] string) {
		int index = chinese ? 1 : 0;
		if (index >= string.length) {
			index = 0;
		}
		return string[index];
	}

	private static int ACTIVITY_SCANNER = 9974;

	// -----物件變數-----
	private Activity activity;
	private Fragment fragment;
	private CodeReaderListener codeReaderListener;
	private Mode mode = Mode.SCAN_MODE;
	private boolean crop = false;
	private String scanPrefix = null;

	// -----建構子-----
	public CodeScanner(final Activity activity, final CodeReaderListener codeReaderListener) {
		this.activity = activity;
		this.codeReaderListener = codeReaderListener;
	}

	public CodeScanner(final Fragment fragment, final CodeReaderListener codeReaderListener) {
		this(fragment.getActivity(), codeReaderListener);
		this.fragment = fragment;
	}

	// -----物件方法-----
	public Activity getActivity() {
		if (activity != null) {
			return activity;
		} else {
			return null;
		}
	}

	public CodeReaderListener getCodeReaderListener() {
		return codeReaderListener;
	}

	public void setCrop(final boolean crop) {
		this.crop = crop;
	}

	public boolean getCrop() {
		return crop;
	}

	public void setMode(final Mode mode) {
		if (mode != null) {
			this.mode = mode;
		} else {
			this.mode = Mode.SCAN_MODE;
		}
	}

	public Mode getMode() {
		return mode;
	}

	public void setScanPrefix(final String scanPrefix) {
		this.scanPrefix = scanPrefix;
	}

	public String getScanPrefix() {
		return scanPrefix;
	}

	public boolean scan() {
		final PackageManager packageManager = activity.getPackageManager();
		final Intent easyBarcodeScanner = new Intent("org.magiclen.barcodescanner.SCAN");
		easyBarcodeScanner.setPackage("org.magiclen.barcodescanner");
		final List<ResolveInfo> list = packageManager.queryIntentActivities(easyBarcodeScanner, PackageManager.MATCH_DEFAULT_ONLY);
		if (list.size() > 0) {
			easyBarcodeScanner.putExtra(SCAN_MODES, mode.toString());
			easyBarcodeScanner.putExtra(USE_CROP, crop);
			easyBarcodeScanner.putExtra(SCAN_PREFIX, scanPrefix);
			if (fragment != null) {
				fragment.startActivityForResult(easyBarcodeScanner, ACTIVITY_SCANNER);
			} else {
				activity.startActivityForResult(easyBarcodeScanner, ACTIVITY_SCANNER);
			}
			return true;
		} else {
			new AlertDialog.Builder(activity).setTitle(getString(STRING_INSTALL_TITLE)).setMessage(getString(STRING_INSTALL_MESSAGE)).setPositiveButton(getString(STRING_INSTALL_INSTALL), new DialogInterface.OnClickListener() {

				@Override
				public void onClick(final DialogInterface dialog, final int which) {
					final String url = getString(STRING_URL_EASY_BARCODE_SCANNER);
					final Intent openURLIntent = new Intent(Intent.ACTION_VIEW);
					openURLIntent.setData(Uri.parse(url));
					final List<ResolveInfo> list = packageManager.queryIntentActivities(openURLIntent, PackageManager.MATCH_DEFAULT_ONLY);
					if (list.size() > 0) {
						final Intent destIntent = Intent.createChooser(openURLIntent, null);
						activity.startActivity(destIntent);
					}
				}

			}).setNegativeButton(getString(STRING_INSTALL_CLOSE), null).show();
			return false;
		}
	}

	public void onActivityResult(final int requestCode, final int resultCode, final Intent data) {
		if (requestCode == ACTIVITY_SCANNER && codeReaderListener != null) {
			if (resultCode == Activity.RESULT_OK) {
				final String resultType = data.getStringExtra("code_type");
				final String resultData = data.getStringExtra("code_data");
				codeReaderListener.codeReadResult(resultType, resultData);
			} else {
				codeReaderListener.codeReadResult(null, null);
			}
		}
	}
}

CodeScanner使用方式十分簡單，一開始要先傳入Activity或是Fragment以及CodeReaderListener將其實體化(new)出來，如下：

CodeReaderListener codeReaderListener = new CodeReaderListener(){
	@Override
	public void codeReadResult(final String type, final String data) {
		// type就是條碼的類型，EAN、ISBN、QRCode...等等
		// data就是條碼的內容，為任意字串
		// 若掃描未完成，type和data的值將為null
	}
}
...
CodeScanner cs = new CodeScanner(activity, codeReaderListener);

接著可以對CodeScanner進行一些設定，像是要掃描的條碼類型(一維條碼、二維條碼、QR Code等)、要接受的條碼內容(條碼內容的開頭必須符合設定才會完成掃描)、是否直接使用小範圍掃描(增大掃描成功率)。如下：

cs.setMode(Mode.QR_CODE_MODE);
cs.setScanPrefix(QR_KEY);
cs.setCrop(true);

再來覆寫(Override)Activity或是Fragment的onActivityResult方法，將CodeScanner的onActivityResult方法加進去。如下：

@Override
protected void onActivityResult(final int requestCode, final int resultCode, final Intent data) {
	cs.onActivityResult(requestCode, resultCode, data);
	super.onActivityResult(requestCode, resultCode, data);
}

之後就可以在任何想要開啟掃描的地方呼叫CodeScanner物件的scan方法，就可以開始進行條碼掃描了。如下：

cs.scan();

不管掃描有沒有結束，當掃描器被關閉的時候，都會呼叫CodeReaderListener的codeReadResult方法，可處理後續的動作。

QRCodeEncoder

QRCodeEncoder是一個Java類別(Class)，可以快速地使用簡易條碼掃描器來協助App產生QR Code。

程式如下：

package org.magiclen.code;

import java.util.List;
import java.util.Locale;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.content.pm.ResolveInfo;
import android.net.Uri;

/**
 * QR Code產生
 * 
 * @author magiclen
 *
 */
public class QRCodeEncoder {

	// -----類別常數-----
	private static final String ENCODE_DATA = "ENCODE_DATA";

	private static final String[] STRING_INSTALL_TITLE = new String[] { "Install Barcode Scanner", "安裝條碼掃描器" };
	private static final String[] STRING_INSTALL_CLOSE = new String[] { "Close", "關閉" };
	private static final String[] STRING_INSTALL_INSTALL = new String[] { "Install", "安裝" };
	private static final String[] STRING_INSTALL_MESSAGE = new String[] { "In order to see the QR code, you neet to install Easy Barcode Scanner first.", "為了能夠看到QR Code，您需要安裝簡易條碼掃描器。" };
	private static final String[] STRING_URL_EASY_BARCODE_SCANNER = new String[] { "https://play.google.com/store/apps/details?id=org.magiclen.barcodescanner" };

	// -----類別變數-----
	private static boolean chinese = isChinese();

	// -----類別方法-----
	private static boolean isChinese() {
		final Locale locale = Locale.getDefault();
		return locale.equals(Locale.CHINESE) || locale.equals(Locale.SIMPLIFIED_CHINESE) || locale.equals(Locale.TRADITIONAL_CHINESE);
	}

	private static String getString(final String[] string) {
		int index = chinese ? 1 : 0;
		if (index >= string.length) {
			index = 0;
		}
		return string[index];
	}

	public static boolean encode(final Activity activity, final String text) {
		final PackageManager packageManager = activity.getPackageManager();
		final Intent easyBarcodeScanner = new Intent("org.magiclen.barcodescanner.ENCODE");
		easyBarcodeScanner.setPackage("org.magiclen.barcodescanner");
		final List<ResolveInfo> list = packageManager.queryIntentActivities(easyBarcodeScanner, PackageManager.MATCH_DEFAULT_ONLY);
		if (list.size() > 0) {
			easyBarcodeScanner.putExtra(ENCODE_DATA, text);
			activity.startActivity(easyBarcodeScanner);
			return true;
		} else {
			new AlertDialog.Builder(activity).setTitle(getString(STRING_INSTALL_TITLE)).setMessage(getString(STRING_INSTALL_MESSAGE)).setPositiveButton(getString(STRING_INSTALL_INSTALL), new DialogInterface.OnClickListener() {

				@Override
				public void onClick(final DialogInterface dialog, final int which) {
					final String url = getString(STRING_URL_EASY_BARCODE_SCANNER);
					final Intent openURLIntent = new Intent(Intent.ACTION_VIEW);
					openURLIntent.setData(Uri.parse(url));
					final List<ResolveInfo> list = packageManager.queryIntentActivities(openURLIntent, PackageManager.MATCH_DEFAULT_ONLY);
					if (list.size() > 0) {
						final Intent destIntent = Intent.createChooser(openURLIntent, null);
						activity.startActivity(destIntent);
					}
				}

			}).setNegativeButton(getString(STRING_INSTALL_CLOSE), null).show();
			return false;
		}
	}

}

QRCodeEncoder不需要實體化即可使用，只要呼叫encode方法並傳入activity和要產生的條碼內容，就可以產生QR Code出來。如下：

QRCodeEncoder.encode(activity, text);