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Java example source code file (Repository.java)

This example Java source code file (Repository.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

javaclass, repository, string

The Repository.java Java example source code

/*
 * reserved comment block
 * DO NOT REMOVE OR ALTER!
 */
package com.sun.org.apache.bcel.internal;

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" and
 *    "Apache BCEL" must not be used to endorse or promote products
 *    derived from this software without prior written permission. For
 *    written permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    "Apache BCEL", nor may "Apache" appear in their name, without
 *    prior written permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

import com.sun.org.apache.bcel.internal.classfile.JavaClass;
import com.sun.org.apache.bcel.internal.util.*;
import java.io.*;

/**
 * The repository maintains informations about class interdependencies, e.g.,
 * whether a class is a sub-class of another. Delegates actual class loading
 * to SyntheticRepository with current class path by default.
 *
 * @see com.sun.org.apache.bcel.internal.util.Repository
 * @see com.sun.org.apache.bcel.internal.util.SyntheticRepository
 *
 * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm
 */
public abstract class Repository {
  private static com.sun.org.apache.bcel.internal.util.Repository _repository =
    SyntheticRepository.getInstance();

  /** @return currently used repository instance
   */
  public static com.sun.org.apache.bcel.internal.util.Repository getRepository() {
    return _repository;
  }

  /** Set repository instance to be used for class loading
   */
  public static void setRepository(com.sun.org.apache.bcel.internal.util.Repository rep) {
    _repository = rep;
  }

  /** Lookup class somewhere found on your CLASSPATH, or whereever the
   * repository instance looks for it.
   *
   * @return class object for given fully qualified class name, or null
   * if the class could not be found or parsed correctly
   */
  public static JavaClass lookupClass(String class_name) {
    try {
      JavaClass clazz = _repository.findClass(class_name);

      if(clazz == null) {
        return _repository.loadClass(class_name);
      } else {
        return clazz;
      }
    } catch(ClassNotFoundException ex) { return null; }
  }

  /**
   * Try to find class source via getResourceAsStream().
   * @see Class
   * @return JavaClass object for given runtime class
   */
  public static JavaClass lookupClass(Class clazz) {
    try {
      return _repository.loadClass(clazz);
    } catch(ClassNotFoundException ex) { return null; }
  }

  /** @return class file object for given Java class.
   */
  public static ClassPath.ClassFile lookupClassFile(String class_name) {
    try {
      return ClassPath.SYSTEM_CLASS_PATH.getClassFile(class_name);
    } catch(IOException e) { return null; }
  }

  /** Clear the repository.
   */
  public static void clearCache() {
    _repository.clear();
  }

  /**
   * Add clazz to repository if there isn't an equally named class already in there.
   *
   * @return old entry in repository
   */
  public static JavaClass addClass(JavaClass clazz) {
    JavaClass old = _repository.findClass(clazz.getClassName());
    _repository.storeClass(clazz);
    return old;
  }

  /**
   * Remove class with given (fully qualified) name from repository.
   */
  public static void removeClass(String clazz) {
    _repository.removeClass(_repository.findClass(clazz));
  }

  /**
   * Remove given class from repository.
   */
  public static void removeClass(JavaClass clazz) {
    _repository.removeClass(clazz);
  }

  /**
   * @return list of super classes of clazz in ascending order, i.e.,
   * Object is always the last element
   */
  public static JavaClass[] getSuperClasses(JavaClass clazz) {
    return clazz.getSuperClasses();
  }

  /**
   * @return list of super classes of clazz in ascending order, i.e.,
   * Object is always the last element. return "null", if class
   * cannot be found.
   */
  public static JavaClass[] getSuperClasses(String class_name) {
    JavaClass jc = lookupClass(class_name);
    return (jc == null? null : getSuperClasses(jc));
  }

  /**
   * @return all interfaces implemented by class and its super
   * classes and the interfaces that those interfaces extend, and so on.
   * (Some people call this a transitive hull).
   */
  public static JavaClass[] getInterfaces(JavaClass clazz) {
    return clazz.getAllInterfaces();
  }

  /**
   * @return all interfaces implemented by class and its super
   * classes and the interfaces that extend those interfaces, and so on
   */
  public static JavaClass[] getInterfaces(String class_name) {
    return getInterfaces(lookupClass(class_name));
  }

  /**
   * Equivalent to runtime "instanceof" operator.
   * @return true, if clazz is an instance of super_class
   */
  public static boolean instanceOf(JavaClass clazz, JavaClass super_class) {
    return clazz.instanceOf(super_class);
  }

  /**
   * @return true, if clazz is an instance of super_class
   */
  public static boolean instanceOf(String clazz, String super_class) {
    return instanceOf(lookupClass(clazz), lookupClass(super_class));
  }

  /**
   * @return true, if clazz is an instance of super_class
   */
  public static boolean instanceOf(JavaClass clazz, String super_class) {
    return instanceOf(clazz, lookupClass(super_class));
  }

  /**
   * @return true, if clazz is an instance of super_class
   */
  public static boolean instanceOf(String clazz, JavaClass super_class) {
    return instanceOf(lookupClass(clazz), super_class);
  }

  /**
   * @return true, if clazz is an implementation of interface inter
   */
  public static boolean implementationOf(JavaClass clazz, JavaClass inter) {
    return clazz.implementationOf(inter);
  }

  /**
   * @return true, if clazz is an implementation of interface inter
   */
  public static boolean implementationOf(String clazz, String inter) {
    return implementationOf(lookupClass(clazz), lookupClass(inter));
  }

  /**
   * @return true, if clazz is an implementation of interface inter
   */
  public static boolean implementationOf(JavaClass clazz, String inter) {
    return implementationOf(clazz, lookupClass(inter));
  }

  /**
   * @return true, if clazz is an implementation of interface inter
   */
  public static boolean implementationOf(String clazz, JavaClass inter) {
    return implementationOf(lookupClass(clazz), inter);
  }
}

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