URLClassPathRepository.java

/*
 * FindBugs - Find bugs in Java programs
 * Copyright (C) 2004, University of Maryland
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

/*
 * Created on Sep 20, 2004
 */
package edu.umd.cs.findbugs.ba;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

import org.apache.bcel.classfile.JavaClass;
import org.apache.bcel.util.ClassPath;
import org.apache.bcel.util.Repository;

import edu.umd.cs.findbugs.SystemProperties;

/**
 * BCEL Repository implementation that uses an URLClassPath to find classes.
 * This class has two specific improvements over BCEL's SyntheticRepository
 * class:
 * <ol>
 * <li>Classpath elements may be added at any time, not just when the object is
 * created.
 * <li>Classpath elements can be URLs. This allows repository lookups to find
 * classes via http URLs, jar URLs, etc.
 * </ol>
 * FindBugs requires and uses both of these capabilities.
 *
 * @author David Hovemeyer
 */
public class URLClassPathRepository implements Repository {
    public static final boolean DEBUG = SystemProperties.getBoolean("findbugs.classpath.debug");

    private static final long serialVersionUID = 1L;

    private Map<String, JavaClass> nameToClassMap;

    private URLClassPath urlClassPath;

    public URLClassPathRepository() {
        this.nameToClassMap = new HashMap<String, JavaClass>();
        this.urlClassPath = new URLClassPath();
    }

    /**
     * Clear the repository and close all underlying resources.
     */
    public void destroy() {
        nameToClassMap.clear();
        urlClassPath.close();
        if (DEBUG) {
            System.out.println("Destroying Repository");
        }
    }

    /**
     * Add a filename or URL to the classpath.
     *
     * @param fileName
     *            filename or URL of classpath entry to add
     * @throws IOException
     */
    public void addURL(String fileName) throws IOException {
        urlClassPath.addURL(fileName);
    }

    /*
     * (non-Javadoc)
     *
     * @see
     * org.apache.bcel.util.Repository#storeClass(org.apache.bcel.classfile.
     * JavaClass)
     */
    public void storeClass(JavaClass javaClass) {
        if (DEBUG)
            System.out.println("Storing class " + javaClass.getClassName() + " in repository");
        JavaClass previous = nameToClassMap.put(javaClass.getClassName(), javaClass);
        if (DEBUG && previous != null) {
            System.out.println("\t==> A previous class was evicted!");
            dumpStack();
        }
        Repository tmp = org.apache.bcel.Repository.getRepository();
        if (tmp != null && tmp != this)
            throw new IllegalStateException("Wrong/multiple BCEL repository");
        if (tmp == null)
            org.apache.bcel.Repository.setRepository(this);
    }

    /*
     * (non-Javadoc)
     *
     * @see
     * org.apache.bcel.util.Repository#removeClass(org.apache.bcel.classfile
     * .JavaClass)
     */
    public void removeClass(JavaClass javaClass) {
        nameToClassMap.remove(javaClass.getClassName());
        if (DEBUG) {
            System.out.println("Removing class " + javaClass.getClassName() + " from Repository");
            dumpStack();
        }
    }

    private void dumpStack() {
        new Throwable().printStackTrace(System.out);
    }

    /*
     * (non-Javadoc)
     *
     * @see org.apache.bcel.util.Repository#findClass(java.lang.String)
     */
    public JavaClass findClass(/*@Nonnull*/ String className) {
        // Make sure we handle class names with slashes.
        // If we don't, we can get into serious trouble: a previously
        // loaded class will appear to be missing (because we're using the
        // wrong name to look it up) and be evicted by some other random
        // version of the class loaded from the classpath.
        String dottedClassName = className.replace('/', '.');

        return nameToClassMap.get(dottedClassName);
    }

    /*
     * (non-Javadoc)
     *
     * @see org.apache.bcel.util.Repository#loadClass(java.lang.String)
     */
    public JavaClass loadClass(/*@Nonnull*/ String className) throws ClassNotFoundException {
        if (className == null)
            throw new IllegalArgumentException("className is null");
        // if (className.indexOf('/') >= 0) throw new IllegalStateException();
        JavaClass javaClass = findClass(className);
        if (javaClass == null) {
            if (DEBUG) {
                System.out.println("Looking up " + className + " on classpath");
                dumpStack();
            }
            javaClass = urlClassPath.lookupClass(className);
            storeClass(javaClass);
        }
        return javaClass;
    }

    /*
     * (non-Javadoc)
     *
     * @see org.apache.bcel.util.Repository#loadClass(java.lang.Class)
     */
    public JavaClass loadClass(Class clazz) throws ClassNotFoundException {
        return loadClass(clazz.getName());
    }

    /*
     * (non-Javadoc)
     *
     * @see org.apache.bcel.util.Repository#clear()
     */
    public void clear() {
        if (DEBUG) {
            System.out.println("Clearing Repository!");
            dumpStack();
        }
        nameToClassMap.clear();
    }

    /*
     * (non-Javadoc)
     *
     * @see org.apache.bcel.util.Repository#getClassPath()
     */
    public ClassPath getClassPath() {
        return new ClassPath(urlClassPath.getClassPath());
    }
}

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