com.davidbracewell.io.JarUtils Maven / Gradle / Ivy

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A set of utilities and tools to speed up and ease programming in Java.
There is a newer version: 0.5
/*
 * (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 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());
  }

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

  private static List getResourcesFromDirectory(Resource resource, Predicate stringMatcher) {
    Preconditions.checkNotNull(resource);
    Preconditions.checkNotNull(stringMatcher);
    Preconditions.checkArgument(resource.isDirectory());

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

    return children;
  }

  private static List getResourcesFromJar(Resource resource, Predicate stringMatcher) {
    JarFile jf = null;
    List resources = new ArrayList<>();
    try {
      jf = new JarFile(resource.asFile().get());
      Enumeration 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 getJarContents(Resource resource, Predicate stringMatcher) {
    Preconditions.checkNotNull(resource);
    Preconditions.checkNotNull(stringMatcher);
    if (resource.isDirectory()) {
      return getResourcesFromDirectory(resource, stringMatcher);
    } else {
      return getResourcesFromJar(resource, stringMatcher);
    }

  }

  /**
   * @return A list of all resources on the classpath
   */
  public static List 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