com.github.jy2.commandline.picocli.ManifestVersionProvider Maven / Gradle / Ivy

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package com.github.jy2.commandline.picocli;

import java.io.IOException;
import java.net.URL;
import java.util.Enumeration;
import java.util.jar.Attributes;
import java.util.jar.Manifest;

import picocli.CommandLine;
import picocli.CommandLine.IVersionProvider;

class ManifestVersionProvider implements IVersionProvider {
	public String[] getVersion() throws Exception {
		Enumeration resources = CommandLine.class.getClassLoader().getResources("META-INF/MANIFEST.MF");
		while (resources.hasMoreElements()) {
			URL url = resources.nextElement();
			try {
				Manifest manifest = new Manifest(url.openStream());
				if (isApplicableManifest(manifest)) {
					Attributes attr = manifest.getMainAttributes();
					return new String[] { get(attr, "Implementation-Title") + " version \""
							+ get(attr, "Implementation-Version") + "\"" };
				}
			} catch (IOException ex) {
				return new String[] { "Unable to read from " + url + ": " + ex };
			}
		}
		return new String[0];
	}

	private boolean isApplicableManifest(Manifest manifest) {
		Attributes attributes = manifest.getMainAttributes();
		return "picocli".equals(get(attributes, "Implementation-Title"));
	}

	private static Object get(Attributes attributes, String key) {
		return attributes.get(new Attributes.Name(key));
	}
}