/* $Id: ImportClassLoader.java 18069 2010-03-06 17:10:42Z linus $
*****************************************************************************
* Copyright (c) 2009-2010 Contributors - see below
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Thomas N.
* tfmorris
*****************************************************************************
*
* Some portions of this file was previously release using the BSD License:
*/
// Copyright (c) 1996-2008 The Regents of the University of California. All
// Rights Reserved. Permission to use, copy, modify, and distribute this
// software and its documentation without fee, and without a written
// agreement is hereby granted, provided that the above copyright notice
// and this paragraph appear in all copies. This software program and
// documentation are copyrighted by The Regents of the University of
// California. The software program and documentation are supplied "AS
// IS", without any accompanying services from The Regents. The Regents
// does not warrant that the operation of the program will be
// uninterrupted or error-free. The end-user understands that the program
// was developed for research purposes and is advised not to rely
// exclusively on the program for any reason. IN NO EVENT SHALL THE
// UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT,
// SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS,
// ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
// THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF
// SUCH DAMAGE. THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY
// WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE
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package org.argouml.uml.reveng;
import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;
import java.net.URLClassLoader;
import java.net.URL;
import java.net.MalformedURLException;
import java.io.File;
import org.apache.log4j.Logger;
import org.argouml.application.api.Argo;
import org.argouml.configuration.Configuration;
/**
* Class to help users reverse engineer class information from arbitrary
* .jar/.class file resources, like an import classpath.<p>
*
* can be used as follows:
*
* <pre>
* <code>
* try {
* ImportClassLoader loader = ImportClassLoader.getInstance();
* // add paths...
* loader.addFile(new File("/opt/lib/myjar.jar"));
*
* Class clazz = loader.loadClass("org.xyz.MyException");
* Object ex = clazz.newInstance();
* cat.info("loaded class ok");
* } catch(Exception e) {
* cat.warn("error loading class: "+e.toString());
* }
* </code>
* </pre>
*
* It supports adding and removing Files from the import classpath.
* And saving and loading the path to/from the users properties file.<p>
*
* It should be possible to make this the system class loader, but
* I haven't got this to work yet:
*
* <pre>
* <code>
* final URLClassLoader urlClassLoader = new URLClassLoader(urls, cl);
* //create a new custom class with the default classloader as its parent
* try {
* EventQueue eq = Toolkit.getDefaultToolkit().getSystemEventQueue();
* eq.invokeAndWait(new Runnable() {
* public void run() {
* Thread.currentThread().setContextClassLoader(urlClassLoader);
* // this will replace the default system class loader with
* // the new custom classloader, so that the jvm will use
* // the new custom classloader to lookup a class
* }
* });
* //...
* </code>
* </pre>
*
* @author alexb
*/
public final class ImportClassLoader extends URLClassLoader {
/**
* Logger.
*/
private static final Logger LOG = Logger.getLogger(ImportClassLoader.class);
private static ImportClassLoader instance;
/**
* The constructor.
*
* @param urls An array of urls.
*/
private ImportClassLoader(URL[] urls) {
super(urls);
}
/**
* Try and return the existing instance if one exists.
*
* @return the instance
* @throws MalformedURLException when the url is bad
*/
public static ImportClassLoader getInstance()
throws MalformedURLException {
if (instance == null) {
String path =
Configuration.getString(Argo.KEY_USER_IMPORT_CLASSPATH,
System.getProperty("user.dir"));
return getInstance(getURLs(path));
} else {
return instance;
}
}
/**
* There is no default constructor for URLClassloader, so we should provide
* urls when creating the instance.
* We create a new instance in this method.
*
* @param urls the URLs
* @return the instance of this class
* @throws MalformedURLException when the URL is bad
*/
public static ImportClassLoader getInstance(URL[] urls)
throws MalformedURLException {
instance = new ImportClassLoader(urls);
return instance;
}
/**
* @param f the file to be added
* @throws MalformedURLException when the URL is bad
*/
public void addFile(File f) throws MalformedURLException {
addURL(f.toURI().toURL());
}
/**
* Remove the given file.
* But we can't remove the last file.
*
* @param f the file to be removed
*/
public void removeFile(File f) {
URL url = null;
try {
url = f.toURI().toURL();
} catch (MalformedURLException e) {
LOG.warn("could not remove file ", e);
return;
}
List<URL> urls = new ArrayList<URL>();
for (URL u : getURLs()) {
if (!url.equals(u)) {
urls.add(u);
}
}
// can't remove the last file
if (urls.size() == 0) {
return;
}
// can't remove from existing one so create new one.
URL[] urlArray = new URL[urls.size()];
urlArray = urls.toArray(urlArray);
instance = new ImportClassLoader(urlArray);
}
/**
* Add the file for which a path is given.
*
* @param path the path in String format
*/
public void setPath(String path) {
StringTokenizer st = new StringTokenizer(path, ";");
st.countTokens();
while (st.hasMoreTokens()) {
String token = st.nextToken();
try {
this.addFile(new File(token));
} catch (MalformedURLException e) {
LOG.warn("could not set path ", e);
}
}
}
/**
* Add the files for which the paths are given, and return in URL format.
* @param path the paths in String format
* @return the URLs
*/
public static URL[] getURLs(String path) {
java.util.List<URL> urlList = new ArrayList<URL>();
StringTokenizer st = new StringTokenizer(path, ";");
while (st.hasMoreTokens()) {
String token = st.nextToken();
try {
urlList.add(new File(token).toURI().toURL());
} catch (MalformedURLException e) {
LOG.error(e);
}
}
URL[] urls = new URL[urlList.size()];
for (int i = 0; i < urls.length; i++) {
urls[i] = urlList.get(i);
}
return urls;
}
/**
* @param paths the paths to the files to be added
*/
public void setPath(Object[] paths) {
for (int i = 0; i < paths.length; i++) {
try {
this.addFile(new File(paths[i].toString()));
} catch (Exception e) {
LOG.warn("could not set path ", e);
}
}
}
/**
* Get the user-configured path.
*/
public void loadUserPath() {
setPath(Configuration.getString(Argo.KEY_USER_IMPORT_CLASSPATH, ""));
}
/**
* Store the user-configured path.
*/
public void saveUserPath() {
Configuration.setString(Argo.KEY_USER_IMPORT_CLASSPATH,
this.toString());
}
@Override
public String toString() {
URL[] urls = this.getURLs();
StringBuilder path = new StringBuilder();
for (int i = 0; i < urls.length; i++) {
path.append(urls[i].getFile());
if (i < urls.length - 1) {
path.append(";");
}
}
return path.toString();
}
}