net.glxn.qrgen.core.scheme.ExtendableQRCodeSchemeParser Maven / Gradle / Ivy

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package net.glxn.qrgen.core.scheme;

import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.net.URL;
import java.util.Collections;
import java.util.Enumeration;
import java.util.LinkedHashSet;
import java.util.Properties;
import java.util.Set;

/**
 * An implementation of {@link QRCodeSchemeParser} which supports the types
 * {@link Wifi}, {@link VCard}, {@link Girocode} and {@link URL}, and may be
 * extended by additional parsers for custom types. 

 * 

 * In order to add a parser, you have to put a properties file named
 * qrcode.meta into your META-INF folder, containing a
 * comma-separated list of your parser class names assigned to the key
 * net.glxn.qrgen.core.scheme.QRCodeSchemeParser. Let's say you
 * have additional parsers with the full qualified names
 * org.me.FooSchemeParser and org.me.BarSchemeParser,
 * your qrcode.meta must have the following entry.

 * 

 * 
 * META-INF/qrcode.meta:
 * 
 *  * net.glxn.qrgen.core.scheme.QRCodeSchemeParser=\
 * org.me.FooSchemeParser,\
 * org.me.BarSchemeParser
 * 
 * 
 * TODO: does this parser stuff make sense at all?
 */
public class ExtendableQRCodeSchemeParser implements QRCodeSchemeParser {

	private Set parser;

	@Override
	public Set> getSupportedSchemes() {
		Set> supportedSchemes = new LinkedHashSet>();
		for (QRCodeSchemeParser parser : getParser()) {
			supportedSchemes.addAll(parser.getSupportedSchemes());
		}
		return supportedSchemes;
	}

	public Object parse(final String qrCodeText) throws UnsupportedEncodingException {
		for (QRCodeSchemeParser parser : getParser()) {
			try {
				return parser.parse(qrCodeText);
			} catch (UnsupportedEncodingException e) {
				// go on
			}
		}
		throw new UnsupportedEncodingException("unkonwn QR code scheme: " + qrCodeText);
	}

	protected Set getParser() {
		if (parser == null) {
			parser = loadParser();
		}
		return parser;
	}

	protected Set loadParser() {
		Set result = new LinkedHashSet();
		try {
			Enumeration resources = this.getClass().getClassLoader().getResources("META-INF/qrcode.meta");
			for (URL url : Collections.list(resources)) {
				Properties properties = new Properties();
				try (InputStream is = url.openStream()) {
					properties.load(is);
					String prop = properties.getProperty(QRCodeSchemeParser.class.getName());
					String[] parserNames = prop.split(",");
					for (String className : parserNames) {
						result.add(createParserInstance(className));
					}
				}
			}
		} catch (Exception e) {
			throw new RuntimeException("failed to load schemes", e);
		}
		result.add(new QRCodeSchemeParserImpl());
		return result;
	}

	protected QRCodeSchemeParser createParserInstance(String className)
			throws InstantiationException, IllegalAccessException, ClassNotFoundException {
		Class clazz = Class.forName(className.trim());
		return (QRCodeSchemeParser) clazz.newInstance();
	}

	static class QRCodeSchemeParserImpl implements QRCodeSchemeParser {

		@Override
		public Object parse(String qrCodeText) throws UnsupportedEncodingException {
			for (Class type : getSupportedSchemes()) {
				Object instance = createInstance(qrCodeText, type);
				if (instance != null) {
					return instance;
				}
			}
			throw new UnsupportedEncodingException("unkonwn QR code scheme: " + qrCodeText);
		}

		protected Object createInstance(final String qrCodeText, final Class type) {
			try {
				return type.getConstructor(null).newInstance(null).parseSchema(qrCodeText);
			} catch (Exception e) {
				return null;
			}
		}

		@Override
		public Set> getSupportedSchemes() {
			Set> supportedSchemes = new LinkedHashSet>();
			supportedSchemes.add(Girocode.class);
			supportedSchemes.add(VCard.class);
			supportedSchemes.add(Wifi.class);
			supportedSchemes.add(BizCard.class);
			supportedSchemes.add(EMail.class);
			supportedSchemes.add(EnterpriseWifi.class);
			supportedSchemes.add(GeoInfo.class);
			supportedSchemes.add(GooglePlay.class);
			supportedSchemes.add(ICal.class);
			supportedSchemes.add(KddiAu.class);
			supportedSchemes.add(MeCard.class);
			supportedSchemes.add(MMS.class);
			supportedSchemes.add(SMS.class);
			supportedSchemes.add(Telephone.class);
			supportedSchemes.add(Url.class);
			return supportedSchemes;
		}

	}

}