Get library versions from loaded war file

Main.java

package com.mycompany;

public class Main {
  public static void main(String[] args){
    Map<String,Object> versions = ResourceGrabber.grabLibraryVersions();
    System.out.println("joda-time: " + versions.get("joda-time").toString());
  }
}

ResourceGrabber.java

package com.mycompany;

import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URISyntaxException;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import javax.servlet.ServletContext;

import com.mycompany.utils.SpringUtil;

public class ResourceGrabber {
	
	private static ResourceGrabber singleton = new ResourceGrabber();
	private ServletContext servletContext;
	
	public ResourceGrabber() {
		servletContext = (ServletContext)SpringUtil.getBean("servletContext");
	}
	
	public static String grabResourceJndi(String resource) {
		URL r;
		try {
			r = singleton.servletContext.getResource(resource);
		} catch(MalformedURLException ex) {
			return "Malformed URL";
		}
		try {
			return r.toURI().toASCIIString();
		} catch (URISyntaxException e) {
			return "Bad URI Syntax: " + r.toString();
		} catch(NullPointerException ex) {
			return null;
		}
	}
	
	public static Map<String,String> grabResource(String resource){
		Map<String,String> data = new HashMap<String,String>();
		data.put("jndi",grabResourceJndi(resource));
		data.put("data",grabResourceData(resource));
		return data;
	}
	
	public static String grabResourceData(String resource) {
		InputStream is = singleton.servletContext.getResourceAsStream(resource);
		if(is == null) {
			return null;
		}
		StringBuilder sb = new StringBuilder(1024);
		try {
		  byte[] readBytes = new byte[1024];
		  while(is.available() > 0) {
			sb.append(new String(readBytes,0,is.read(readBytes)));
		  }
		}catch(IOException ex) {}
		return sb.toString();
	}
	
	public static Map<String,Object> grabManifest() {
		String manifest = grabResourceData("/META-INF/MANIFEST.MF");
		if(manifest == null) {
			return null;
		}
		manifest = manifest.replaceAll("[\\r\\n]{1,2} ","");
		Map<String,Object> ret = new HashMap<String,Object>();
		for(String s : manifest.split("[\\r\\n]+")) {
			String[] spl = s.split(": ");
			String left = spl[0];
			if(spl.length > 1) {
				if(spl[1].contains(",")) {
					ret.put(left,spl[1].split(","));
				} else {
					ret.put(left,spl[1]);
				}
			}
		}
		return ret;
	}
	
	public static Map<String,String> grabLibraryVersions() {
		Map<String,String> ret = new HashMap<String,String>();
		Map<String,Object> manifest = grabManifest();
		if(manifest == null) {
			return null;
		}
		Pattern p = Pattern.compile("^WEB-INF/lib/([^\\.]+)-(.+?)\\.jar$");
		for(String s : (String[])manifest.get("Bundle-ClassPath")) {
			Matcher m = p.matcher(s);
			if(m.matches()) {
				ret.put(m.group(1),m.group(2));
			}
		}
		return ret;
	}
	
	public static Set<String> grabResourcePaths(String resource) {
		return singleton.servletContext.getResourcePaths(resource);
	}

}

SpringUtil.java

package com.mycompany.utils;

import org.springframework.context.ApplicationContext;
import org.codehaus.groovy.grails.web.context.ServletContextHolder;
import org.codehaus.groovy.grails.web.servlet.GrailsApplicationAttributes;

public class SpringUtil {

  public static ApplicationContext getCtx() {
    return getApplicationContext();
  }

  public static ApplicationContext getApplicationContext() {
    return (ApplicationContext) ServletContextHolder.getServletContext().getAttribute(GrailsApplicationAttributes.APPLICATION_CONTEXT);
  }

  @SuppressWarnings("unchecked")
  public static <T> T getBean(String beanName) {
    return (T) getApplicationContext().getBean(beanName);
  }

}