Search over classpath retrieving classes that implement a certain interface
/*
* The contents of this file are subject to the Sapient Public License
* Version 1.0 (the "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
* http://carbon.sf.net/License.html.
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for
* the specific language governing rights and limitations under the License.
*
* The Original Code is The Carbon Component Framework.
*
* The Initial Developer of the Original Code is Sapient Corporation
*
* Copyright (C) 2003 Sapient Corporation. All Rights Reserved.
*/
import java.io.File;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
import java.util.StringTokenizer;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;
/**
* <p>This class implements the capability to search over the current classpath
* retrieving classes that implement a certain interface.</p>
*
* Copyright 2001 Sapient
* @since carbon 1.0
* @author Greg Hinkle, June 2001
* @version $Revision: 1.10 $($Author: dvoet $ / $Date: 2003/05/05 21:21:23 $)
*/
public class ClassFinder {
/**
* Tracks the count of classes found that match the
* provided criteria.
*/
protected long foundClasses = 0;
/**
* The super class criteria
*/
protected Class superClass = null;
/**
* The required substring path criteria for this searcher
*/
protected String requiredPathSubstring = null;
/**
* The set of classes found matching the provided criteria.
*/
protected Set classes = new HashSet(2000);
/**
* <p>Instantiates the type of MBeanHarvester that will return all classes
* in the entire classpath.</p>
*/
public ClassFinder() {
}
/**
* <p>Instantiates the type of MBeanHarvester that will return all classes
* that are assignable to the supplied class. This would include all
* implementations of it, if it is an interface or it and all subclasses
* of it if it's a class.</p>
*
* @param superClass the Class that should be searched for along with
* implementations and subclasses
*/
public ClassFinder(Class superClass) {
this.superClass = superClass;
}
/**
* <p>Instantiates the type of MBeanHarvester that will return all classes
* that are assignable to the supplied class and are part of the supplied
* package. This would include all implementations of it, if it is an
* interface or it and all subclasses of it if it's a class. The
* supplied <code>requiredPathSubstring must be part of the fully
* qualified classname.</p>
*
* @param superClass the Class that should be searched for along with
* implementations and subclasses
* @param requiredPathSubstring the String part that must be found in the
* classes FQN
*/
public ClassFinder(Class superClass, String requiredPathSubstring) {
this.superClass = superClass;
this.requiredPathSubstring = requiredPathSubstring;
}
/**
* <p>Adds a class name to the list of found classes if and only if it meets
* the configured requirements.</p>
*
* @param className the FQN String name of the class to add
*/
protected void addClassName(String className) {
// Only add this class if we're not checking for a particular
// substring of the FQN or we find that substring
if ((this.requiredPathSubstring == null) ||
(className.indexOf(this.requiredPathSubstring) >= 0)) {
if (this.superClass == null) {
this.classes.add(className);
} else {
try {
// TODO: GH - add a way to search other classpaths and the
// system classpath.
Class theClass =
Class.forName(
className,
false,
this.getClass().getClassLoader());
if (this.superClass.isAssignableFrom(theClass)) {
this.classes.add(className);
}
} catch (ClassNotFoundException cnfe) {
// Used to catch mis-parsed classnames
} catch (Throwable t) {
// Used to catch JVM security and linkage errors
}
}
}
}
/**
* <p>Used to retrieve the results <code>Set</code> from this harvester's
* search.</p>
*
* @return Set the set of classes that meet this harvester's requirements
*/
public Set getClasses() {
// 1) tokenize classpath
String classpath = System.getProperty("java.class.path");
String pathSeparator = System.getProperty("path.separator");
StringTokenizer st = new StringTokenizer(classpath,pathSeparator);
// 2) for each element in the classpath
while (st.hasMoreTokens()) {
File currentDirectory = new File(st.nextToken());
processFile(currentDirectory.getAbsolutePath(),"");
}
return this.classes;
}
/**
* Recursively search through Directories with special checks to recognize
* zip and jar files. (Zip and Jar files return true from
* <File>.isDirectory())
* @param base the base file path to search
* @param current the current recursively searched file path being searched
*/
private void processFile(String base, String current) {
File currentDirectory = new File(base + File.separatorChar + current);
// Handle special for archives
if (isArchive(currentDirectory.getName())) {
try {
processZip(new ZipFile(currentDirectory));
} catch (Exception e) {
// The directory was not found so the classpath was probably in
// error or we don't have rights to it
}
return;
} else {
Set directories = new HashSet();
File[] children = currentDirectory.listFiles();
// if no children, return
if (children == null || children.length == 0) {
return;
}
// check for classfiles
for (int i = 0; i < children.length; i++) {
File child = children[i];
if (child.isDirectory()) {
directories.add(children[i]);
} else {
if (child.getName().endsWith(".class")) {
String className =
getClassName(
current +
((current == "") ? "" : File.separator) +
child.getName());
addClassName(className);
this.foundClasses++;
}
}
}
//call process file on each directory. This is an iterative call!!
for (Iterator i = directories.iterator(); i.hasNext(); ) {
processFile(base, current + ((current=="")?"":File.separator) +
((File)i.next()).getName());
}
}
}
/**
* <p>Looks at the name of a file to determine if it is an archive</p>
* @param name the name of a file
* @return true if a file in the classpath is an archive
* such as a Jar or Zip file
*/
protected boolean isArchive(String name) {
if ((name.endsWith(".jar") ||
(name.endsWith(".zip")))) {
return true;
} else {
return false;
}
}
/**
* <p>Returns the Fully Qualified Class name of a class from it's path
* @param fileName the full path to a class
* @return the FQN of a class
*/
protected String getClassName(String fileName) {
String newName = fileName.replace(File.separatorChar,'.');
// Because zipfiles don't have platform specific seperators
newName = newName.replace('/','.');
return newName.substring(0, fileName.length() - 6);
}
/**
* <P>Iterates through the files in a zip looking for files that may be
* classes. This is not recursive as zip's in zip's are not searched by the
* classloader either.</p>
*
* @param file The ZipFile to be searched
*/
protected void processZip(ZipFile file) {
Enumeration files = file.entries();
while (files.hasMoreElements()) {
Object tfile = files.nextElement();
ZipEntry child = (ZipEntry) tfile;
if (child.getName().endsWith(".class")) {
addClassName(getClassName(child.getName()));
this.foundClasses++;
}
}
}
}
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