Classpath.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.felix.ipojo.manipulator.util;

import java.io.File;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.*;

/**
 * An ordered list of classpath elements with set behaviour. A Classpath is immutable and thread safe.
 * This class let retrieve an isolated classloader to load classes from a set of jars.
 */
public class Classpath implements Iterable<String> {

    private final List<String> unmodifiableElements;

    public static Classpath join(Classpath firstClasspath, Classpath secondClasspath) {
        LinkedHashSet<String> accumulated = new LinkedHashSet<String>();
        if (firstClasspath != null) firstClasspath.addTo(accumulated);
        if (secondClasspath != null) secondClasspath.addTo(accumulated);
        return new Classpath(accumulated);
    }


    private void addTo(Collection<String> c) {
        c.addAll(unmodifiableElements);
    }

    private Classpath() {
        this.unmodifiableElements = Collections.emptyList();
    }


    public Classpath(Classpath other, String additionalElement) {
        ArrayList<String> elems = new ArrayList<String>(other.unmodifiableElements);
        elems.add(additionalElement);
        this.unmodifiableElements = Collections.unmodifiableList(elems);
    }

    public Classpath(Iterable<String> paths) {
        List<String> newCp = new ArrayList<String>();
        for (String element : paths) {
            newCp.add(element);
        }
        this.unmodifiableElements = Collections.unmodifiableList(newCp);
    }

    public static Classpath emptyClasspath() {
        return new Classpath();
    }

    public Classpath addClassPathElementUrl(String path) {
        if (path == null) {
            throw new IllegalArgumentException("Null is not a valid class path element url.");
        }
        return !unmodifiableElements.contains(path) ? new Classpath(this, path) : this;
    }

    public List<String> getClassPath() {
        return unmodifiableElements;
    }

    public List<URL> getAsUrlList()
            throws MalformedURLException {
        List<URL> urls = new ArrayList<URL>();
        for (String path : unmodifiableElements) {
            File f = new File(path);
            urls.add(f.toURI().toURL());
        }
        return urls;
    }

    public void writeToSystemProperty(String propertyName) {
        StringBuilder sb = new StringBuilder();
        for (String element : unmodifiableElements) {
            sb.append(element).append(File.pathSeparatorChar);
        }
        System.setProperty(propertyName, sb.toString());
    }

    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }

        Classpath classpath = (Classpath) o;

        return !(unmodifiableElements
                != null ? !unmodifiableElements.equals(classpath.unmodifiableElements) : classpath.unmodifiableElements != null);

    }

    public ClassLoader createClassLoader(ClassLoader parent, boolean childDelegation)
            throws RuntimeException {
        try {
            List urls = getAsUrlList();
            IsolatedClassLoader classLoader = new IsolatedClassLoader(parent, childDelegation);
            for (Object url1 : urls) {
                URL url = (URL) url1;
                classLoader.addURL(url);
            }
            return classLoader;
        } catch (MalformedURLException e) {
            throw new RuntimeException("When creating classloader", e);
        }
    }

    public ClassLoader createClassLoader()
            throws RuntimeException {
        try {
            List urls = getAsUrlList();
            IsolatedClassLoader classLoader = new IsolatedClassLoader();
            for (Object url1 : urls) {
                URL url = (URL) url1;
                classLoader.addURL(url);
            }
            return classLoader;
        } catch (MalformedURLException e) {
            throw new RuntimeException("When creating classloader", e);
        }
    }


    public int hashCode() {
        return unmodifiableElements != null ? unmodifiableElements.hashCode() : 0;
    }

    public String getLogMessage(String descriptor) {
        StringBuilder result = new StringBuilder();
        result.append(descriptor).append(" classpath:");
        for (String element : unmodifiableElements) {
            result.append("  ").append(element);
        }
        return result.toString();
    }

    public String getCompactLogMessage(String descriptor) {
        StringBuilder result = new StringBuilder();
        result.append(descriptor).append(" classpath:");
        for (String element : unmodifiableElements) {
            result.append("  ");
            if (element != null) {
                int pos = element.lastIndexOf(File.separatorChar);
                if (pos >= 0) {
                    result.append(element.substring(pos + 1));
                } else {
                    result.append(element);
                }

            } else {
                result.append(element);
            }
        }
        return result.toString();
    }

    public Iterator<String> iterator() {
        return unmodifiableElements.iterator();
    }
}