com.davidbracewell.io.JarUtils.java Source code

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Here is the source code for com.davidbracewell.io.JarUtils.java

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/*
 * (c) 2005 David B. Bracewell
 *
 * 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 com.davidbracewell.io;

import com.davidbracewell.SystemInfo;
import com.davidbracewell.io.resource.ClasspathResource;
import com.davidbracewell.io.resource.FileResource;
import com.davidbracewell.io.resource.Resource;
import com.google.common.base.Preconditions;
import com.google.common.base.Predicate;
import com.google.common.base.Predicates;
import com.google.common.base.Throwables;

import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;
import java.util.List;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;

/**
 * @author David B. Bracewell
 */
public class JarUtils {

    private static final List<Resource> classpathResources = new ArrayList<>();

    /**
     * Gets the jar file that a class is stored in.
     *
     * @param clazz The class whose associated jar file is descried.
     * @return The Resource (jar file) for the class
     */
    public static Resource getJar(Class<?> clazz) {
        URL fileURL = Preconditions.checkNotNull(clazz).getProtectionDomain().getCodeSource().getLocation();
        return new FileResource(fileURL.getFile());
    }

    /**
     * <p> Traverse a jar file and get the package names in it </p>
     *
     * @param resource The jar file to traverse
     * @return A Set of package names
     */
    public static List<Resource> getJarContents(Resource resource) {
        return getResourcesFromJar(resource, Predicates.alwaysTrue());
    }

    private static List<Resource> getResourcesFromDirectory(Resource resource,
            Predicate<? super String> stringMatcher) {
        Preconditions.checkNotNull(resource);
        Preconditions.checkNotNull(stringMatcher);
        Preconditions.checkArgument(resource.asFile().isDirectory());

        List<Resource> children = new ArrayList<>();
        for (Resource child : resource.getChildren()) {
            children.add(child);
            if (child.asFile().isDirectory()) {
                children.addAll(getResourcesFromDirectory(child, stringMatcher));
            }
        }

        return children;
    }

    private static List<Resource> getResourcesFromJar(Resource resource, Predicate<? super String> stringMatcher) {
        JarFile jf = null;
        List<Resource> resources = new ArrayList<>();
        try {
            jf = new JarFile(resource.asFile());
            Enumeration<JarEntry> e = jf.entries();
            while (e.hasMoreElements()) {
                String name = e.nextElement().getName();
                if (stringMatcher.apply(name)) {
                    resources.add(new ClasspathResource(name));
                }
            }
        } catch (IOException e) {
            throw Throwables.propagate(e);
        } finally {
            QuietIO.closeQuietly(jf);
        }
        return resources;
    }

    private static List<Resource> getJarContents(Resource resource, Predicate<? super String> stringMatcher) {
        Preconditions.checkNotNull(resource);
        Preconditions.checkNotNull(stringMatcher);
        if (resource.asFile().isDirectory()) {
            return getResourcesFromDirectory(resource, stringMatcher);
        } else {
            return getResourcesFromJar(resource, stringMatcher);
        }

    }

    /**
     * @return A list of all resources on the classpath
     */
    public static List<Resource> getClasspathResources() {
        synchronized (classpathResources) {
            if (classpathResources.isEmpty()) {
                for (String jar : SystemInfo.JAVA_CLASS_PATH.split(SystemInfo.PATH_SEPARATOR)) {
                    File file = new File(jar);
                    if (file.isDirectory()) {
                        classpathResources.addAll(new FileResource(file).getChildren(true));
                    } else {
                        classpathResources.addAll(getJarContents(Resources.fromFile(jar), Predicates.alwaysTrue()));
                    }
                }
            }
            return Collections.unmodifiableList(classpathResources);
        }
    }

}//END OF JarUtils