Struts example source code file (ClassPathFinder.java)

This example Struts source code file (ClassPathFinder.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Struts tags/keywords

classloader, file, file, hashmap, io, net, network, patternmatcher, string, string, uri, url, urlclassloader, urlclassloader, util, vector, vector, wildcardhelper

The Struts ClassPathFinder.java source code

/*
 * $Id: ClassPathFinder.java 894087 2009-12-27 18:00:13Z martinc $
 *
 * Copyright 2003-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.opensymphony.xwork2.util;

import com.opensymphony.xwork2.XWorkException;

import java.io.File;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.HashMap;
import java.util.Vector;

/**
 * This class is an utility class that will search through the classpath
 * for files whose names match the given pattern. The filename is tested
 * using the given implementation of {@link com.opensymphony.xwork2.util.PatternMatcher} by default it 
 * uses {@link com.opensymphony.xwork2.util.WildcardHelper}
 *
 * @version $Rev: 894087 $ $Date: 2009-12-27 19:00:13 +0100 (Sun, 27 Dec 2009) $
 */
public class ClassPathFinder {
	
	/**
     * The String pattern to test against.
     */
	private String pattern ;
	
	private int[] compiledPattern ;
	
	/**
     * The PatternMatcher implementation to use
     */
	private PatternMatcher<int[]> patternMatcher = new WildcardHelper();
	
	private Vector<String> compared = new Vector();
	
	/**
	 * retrieves the pattern in use
	 */
	public String getPattern() {
		return pattern;
	}

	/**
	 * sets the String pattern for comparing filenames
	 * @param pattern
	 */
	public void setPattern(String pattern) {
		this.pattern = pattern;
	}

	/**
     * Builds a {@link java.util.Vector} containing Strings which each name a file
     * who's name matches the pattern set by setPattern(String). The classpath is 
     * searched recursively, so use with caution.
     *
     * @return Vector<String> containing matching filenames
     */
	public Vector<String> findMatches() {
		Vector<String> matches = new Vector();
		URLClassLoader cl = getURLClassLoader();
		if (cl == null ) {
			throw new XWorkException("unable to attain an URLClassLoader") ;
		}
		URL[] parentUrls = cl.getURLs();
		compiledPattern = (int[]) patternMatcher.compilePattern(pattern);
		for (URL url : parentUrls) {
			if (!"file".equals(url.getProtocol())) {
				continue ;
			}
			URI entryURI ;
			try {
				entryURI = url.toURI();
			} catch (URISyntaxException e) {
				continue;
			}
			File entry = new File(entryURI) ;
			Vector<String> results = checkEntries(entry.list(), entry, "");
			if (results != null ) {
				matches.addAll(results);
			}
		}
		return matches;
	}
	
	private Vector<String> checkEntries(String[] entries, File parent, String prefix) {
		
		if (entries == null ) {
			return null;
		}
		
		Vector<String> matches = new Vector();
		for (String listEntry : entries) {
			File tempFile ;
			if (!"".equals(prefix) ) {
				tempFile = new File(parent, prefix + "/" + listEntry);
			}
			else {
				tempFile = new File(parent, listEntry);
			}
			if (tempFile.isDirectory() && 
					!(".".equals(listEntry) || "..".equals(listEntry)) ) {
				if	(!"".equals(prefix) ) {
					matches.addAll(checkEntries(tempFile.list(), parent, prefix + "/" + listEntry));
				}
				else {
					matches.addAll(checkEntries(tempFile.list(), parent, listEntry));
				}
			}
			else {
				
				String entryToCheck ;
				if ("".equals(prefix)) {
					entryToCheck = listEntry ;
				}
				else {
					entryToCheck = prefix + "/" + listEntry ;
				}
				
				if (compared.contains(entryToCheck) ) {
					continue;
				}
				else {
					compared.add(entryToCheck) ;
				}
				
				boolean doesMatch = patternMatcher.match(new HashMap<String,String>(), entryToCheck, compiledPattern);
				if (doesMatch) {
					matches.add(entryToCheck);
				}
			}
		}
		return matches ;
	}

	/**
	 * sets the PatternMatcher implementation to use when comparing filenames
	 * @param patternMatcher
	 */
	public void setPatternMatcher(PatternMatcher<int[]> patternMatcher) {
		this.patternMatcher = patternMatcher;
	}

	private URLClassLoader getURLClassLoader() {
		URLClassLoader ucl = null;
		ClassLoader loader = Thread.currentThread().getContextClassLoader();
		
		if(! (loader instanceof URLClassLoader)) {
			loader = ClassPathFinder.class.getClassLoader();
			if (loader instanceof URLClassLoader) {
				ucl = (URLClassLoader) loader ;
			}
		}
		else {
			ucl = (URLClassLoader) loader;
		}
		
		return ucl ;
	}
}