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Java example source code file (ClassPath.java)

This example Java source code file (ClassPath.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

arraylist, classfile, classpath, couldn\'t, datainputstream, dir, inputstream, ioexception, pathentry, serializable, string, stringbuffer, stringtokenizer, util, zip, zipfile

The ClassPath.java Java example source code

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

/* ====================================================================
 * 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 java.util.*;
import java.util.zip.*;
import java.io.*;

/**
 * Responsible for loading (class) files from the CLASSPATH. Inspired by
 * sun.tools.ClassPath.
 *
 * @version $Id: ClassPath.java,v 1.4 2007-07-19 04:34:52 ofung Exp $
 * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm
 */
public class ClassPath implements Serializable {
  public static final ClassPath SYSTEM_CLASS_PATH = new ClassPath();

  private PathEntry[] paths;
  private String      class_path;

  /**
   * Search for classes in given path.
   */
  public ClassPath(String class_path) {
    this.class_path = class_path;

    ArrayList vec = new ArrayList();

    for(StringTokenizer tok=new StringTokenizer(class_path,
                            SecuritySupport.getSystemProperty("path.separator"));
        tok.hasMoreTokens();)
    {
      String path = tok.nextToken();

      if(!path.equals("")) {
        File file = new File(path);

        try {
          if(SecuritySupport.getFileExists(file)) {
            if(file.isDirectory())
              vec.add(new Dir(path));
            else
              vec.add(new Zip(new ZipFile(file)));
          }
        } catch(IOException e) {
          System.err.println("CLASSPATH component " + file + ": " + e);
        }
      }
    }

    paths = new PathEntry[vec.size()];
    vec.toArray(paths);
  }

  /**
   * Search for classes in CLASSPATH.
   * @deprecated Use SYSTEM_CLASS_PATH constant
   */
  public ClassPath() {
    // this(getClassPath());
    this("");
  }

  /** @return used class path string
   */
  public String toString() {
    return class_path;
  }

  public int hashCode() {
    return class_path.hashCode();
  }

  public boolean equals(Object o) {
    if(o instanceof ClassPath) {
      return class_path.equals(((ClassPath)o).class_path);
    }

    return false;
  }

  private static final void getPathComponents(String path, ArrayList list) {
    if(path != null) {
      StringTokenizer tok = new StringTokenizer(path, File.pathSeparator);

      while(tok.hasMoreTokens()) {
        String name = tok.nextToken();
        File   file = new File(name);

        if(SecuritySupport.getFileExists(file)) {
          list.add(name);
        }
      }
    }
  }

  /** Checks for class path components in the following properties:
   * "java.class.path", "sun.boot.class.path", "java.ext.dirs"
   *
   * @return class path as used by default by BCEL
   */
  public static final String getClassPath() {

    String class_path, boot_path, ext_path;

    try {
      class_path = SecuritySupport.getSystemProperty("java.class.path");
      boot_path  = SecuritySupport.getSystemProperty("sun.boot.class.path");
      ext_path   = SecuritySupport.getSystemProperty("java.ext.dirs");
    }
    catch (SecurityException e) {
        return "";
    }

    ArrayList list = new ArrayList();

    getPathComponents(class_path, list);
    getPathComponents(boot_path, list);

    ArrayList dirs = new ArrayList();
    getPathComponents(ext_path, dirs);

    for(Iterator e = dirs.iterator(); e.hasNext(); ) {
      File ext_dir = new File((String)e.next());
      String[] extensions = SecuritySupport.getFileList(ext_dir, new FilenameFilter() {
        public boolean accept(File dir, String name) {
          name = name.toLowerCase();
          return name.endsWith(".zip") || name.endsWith(".jar");
        }
      });

      if(extensions != null)
        for(int i=0; i < extensions.length; i++)
          list.add(ext_path + File.separatorChar + extensions[i]);
    }

    StringBuffer buf = new StringBuffer();

    for(Iterator e = list.iterator(); e.hasNext(); ) {
      buf.append((String)e.next());

      if(e.hasNext())
        buf.append(File.pathSeparatorChar);
    }

    return buf.toString().intern();
  }

  /**
   * @param name fully qualified class name, e.g. java.lang.String
   * @return input stream for class
   */
  public InputStream getInputStream(String name) throws IOException {
    return getInputStream(name, ".class");
  }

  /**
   * Return stream for class or resource on CLASSPATH.
   *
   * @param name fully qualified file name, e.g. java/lang/String
   * @param suffix file name ends with suff, e.g. .java
   * @return input stream for file on class path
   */
  public InputStream getInputStream(String name, String suffix) throws IOException {
    InputStream is = null;

    try {
      is = getClass().getClassLoader().getResourceAsStream(name + suffix);
    } catch(Exception e) { }

    if(is != null)
      return is;

    return getClassFile(name, suffix).getInputStream();
  }

  /**
   * @param name fully qualified file name, e.g. java/lang/String
   * @param suffix file name ends with suff, e.g. .java
   * @return class file for the java class
   */
  public ClassFile getClassFile(String name, String suffix) throws IOException {
    for(int i=0; i < paths.length; i++) {
      ClassFile cf;

      if((cf = paths[i].getClassFile(name, suffix)) != null)
        return cf;
    }

    throw new IOException("Couldn't find: " + name + suffix);
  }

  /**
   * @param name fully qualified class name, e.g. java.lang.String
   * @return input stream for class
   */
  public ClassFile getClassFile(String name) throws IOException {
    return getClassFile(name, ".class");
  }

  /**
   * @param name fully qualified file name, e.g. java/lang/String
   * @param suffix file name ends with suffix, e.g. .java
   * @return byte array for file on class path
   */
  public byte[] getBytes(String name, String suffix) throws IOException {
    InputStream is = getInputStream(name, suffix);

    if(is == null)
      throw new IOException("Couldn't find: " + name + suffix);

    DataInputStream dis   = new DataInputStream(is);
    byte[]          bytes = new byte[is.available()];
    dis.readFully(bytes);
    dis.close(); is.close();

    return bytes;
  }

  /**
   * @return byte array for class
   */
  public byte[] getBytes(String name) throws IOException {
    return getBytes(name, ".class");
  }

  /**
   * @param name name of file to search for, e.g. java/lang/String.java
   * @return full (canonical) path for file
   */
  public String getPath(String name) throws IOException {
    int    index  = name.lastIndexOf('.');
    String suffix = "";

    if(index > 0) {
      suffix = name.substring(index);
      name   = name.substring(0, index);
    }

    return getPath(name, suffix);
  }

  /**
   * @param name name of file to search for, e.g. java/lang/String
   * @param suffix file name suffix, e.g. .java
   * @return full (canonical) path for file, if it exists
   */
  public String getPath(String name, String suffix) throws IOException {
    return getClassFile(name, suffix).getPath();
  }

  private static abstract class PathEntry implements Serializable {
    abstract ClassFile getClassFile(String name, String suffix) throws IOException;
  }

  /** Contains information about file/ZIP entry of the Java class.
   */
  public interface ClassFile {
    /** @return input stream for class file.
     */
    public abstract InputStream getInputStream() throws IOException;

    /** @return canonical path to class file.
     */
    public abstract String getPath();

    /** @return base path of found class, i.e. class is contained relative
     * to that path, which may either denote a directory, or zip file
     */
    public abstract String getBase();

    /** @return modification time of class file.
     */
    public abstract long getTime();

    /** @return size of class file.
     */
    public abstract long getSize();
  }

  private static class Dir extends PathEntry {
    private String dir;

    Dir(String d) { dir = d; }

    ClassFile getClassFile(String name, String suffix) throws IOException {
      final File file = new File(dir + File.separatorChar +
                                 name.replace('.', File.separatorChar) + suffix);

      return SecuritySupport.getFileExists(file)? new ClassFile() {
        public InputStream getInputStream() throws IOException { return new FileInputStream(file); }

        public String      getPath()        { try {
          return file.getCanonicalPath();
        } catch(IOException e) { return null; }

        }
        public long        getTime()        { return file.lastModified(); }
        public long        getSize()        { return file.length(); }
        public String getBase() {  return dir;  }

      } : null;
    }

    public String toString() { return dir; }
  }

  private static class Zip extends PathEntry {
    private ZipFile zip;

    Zip(ZipFile z) { zip = z; }

    ClassFile getClassFile(String name, String suffix) throws IOException {
      final ZipEntry entry = zip.getEntry(name.replace('.', '/') + suffix);

      return (entry != null)? new ClassFile() {
        public InputStream getInputStream() throws IOException { return zip.getInputStream(entry); }
        public String      getPath()        { return entry.toString(); }
        public long        getTime()        { return entry.getTime(); }
        public long        getSize()       { return entry.getSize(); }
        public String getBase() {
          return zip.getName();
        }
      } : null;
    }
  }
}

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