JarResources.java

/*
 * This file is part of JGAP.
 *
 * JGAP offers a dual license model containing the LGPL as well as the MPL.
 *
 * For licensing information please see the file license.txt included with JGAP
 * or have a look at the top of class org.jgap.Chromosome which representatively
 * includes the JGAP license policy applicable for any file delivered with JGAP.
 */
package org.jgap.util;

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

/**
 * JarResources maps all resources included in a zip or jar file.
 * Additionaly, it provides a method to extract one as a blob.
 *
 * @author unknown
 * @author Klaus Meffert (integrated into JGAP)
 * @since 3.2
 */
public final class JarResources {
  /** String containing the CVS revision. Read out via reflection!*/
  private final static String CVS_REVISION = "$Revision: 1.3 $";

  // external debug flag
  public boolean debugOn = false;

  // jar resource mapping tables
  private Hashtable htSizes = new Hashtable();

  private Hashtable htJarContents = new Hashtable();

  // a jar file
  private String jarFileName;

  /**
   * creates a JarResources. It extracts all resources from a Jar
   * into an internal hashtable, keyed by resource names.
   * @param jarFileName a jar or zip file
   */
  public JarResources(String jarFileName) {
    this.jarFileName = jarFileName;
    init();
  }

  /**
   * Extracts a jar resource as a blob.
   *
   * @param name a resource name
   * @return extracted blob
   */
  public byte[] getResource(String name) {
    return (byte[]) htJarContents.get(name);
  }

  /**
   * initializes internal hash tables with Jar file resources.
   */
  private void init() {
    try {
      // extracts just sizes only.
      ZipFile zf = new ZipFile(jarFileName);
      Enumeration e = zf.entries();
      while (e.hasMoreElements()) {
        ZipEntry ze = (ZipEntry) e.nextElement();
        if (debugOn) {
          System.out.println(dumpZipEntry(ze));
        }
        htSizes.put(ze.getName(), new Integer( (int) ze.getSize()));
      }
      zf.close();
      // extract resources and put them into the hashtable.
      FileInputStream fis = new FileInputStream(jarFileName);
      BufferedInputStream bis = new BufferedInputStream(fis);
      ZipInputStream zis = new ZipInputStream(bis);
      ZipEntry ze = null;
      while ( (ze = zis.getNextEntry()) != null) {
        if (ze.isDirectory()) {
          continue;
        }
        if (debugOn) {
          System.out.println(
              "ze.getName()=" + ze.getName() + "," + "getSize()=" + ze.getSize()
              );
        }
        int size = (int) ze.getSize();
        // -1 means unknown size.
        if (size == -1) {
          size = ( (Integer) htSizes.get(ze.getName())).intValue();
        }
        byte[] b = new byte[ (int) size];
        int rb = 0;
        int chunk = 0;
        while ( ( (int) size - rb) > 0) {
          chunk = zis.read(b, rb, (int) size - rb);
          if (chunk == -1) {
            break;
          }
          rb += chunk;
        }
        // add to internal resource hashtable
        htJarContents.put(ze.getName(), b);
        if (debugOn) {
          System.out.println(
              ze.getName() + "  rb=" + rb +
              ",size=" + size +
              ",csize=" + ze.getCompressedSize()
              );
        }
      }
    } catch (NullPointerException e) {
      System.out.println("done.");
    } catch (FileNotFoundException e) {
      e.printStackTrace();
    } catch (IOException e) {
      e.printStackTrace();
    }
  }

  /**
   * Dumps a zip entry into a string.
   *
   * @param a_ze a ZipEntry
   * @return info about the zip entry
   */
  private String dumpZipEntry(ZipEntry a_ze) {
    StringBuffer sb = new StringBuffer();
    if (a_ze.isDirectory()) {
      sb.append("d ");
    }
    else {
      sb.append("f ");
    }
    if (a_ze.getMethod() == ZipEntry.STORED) {
      sb.append("stored   ");
    }
    else {
      sb.append("defalted ");
    }
    sb.append(a_ze.getName());
    sb.append("\t");
    sb.append("" + a_ze.getSize());
    if (a_ze.getMethod() == ZipEntry.DEFLATED) {
      sb.append("/" + a_ze.getCompressedSize());
    }
    return (sb.toString());
  }

  /**
   * Is a test driver. Given a jar file and a resource name, it trys to
   * extract the resource and then tells us whether it could or not.
   *
   * <strong>Example</strong>
   * Let's say you have a JAR file which jarred up a bunch of gif image
   * files. Now, by using JarResources, you could extract, create, and display
   * those images on-the-fly.
   * <pre>
   *     ...
   *     JarResources JR=new JarResources("GifBundle.jar");
   *     Image image=Toolkit.createImage(JR.getResource("logo.gif");
   *     Image logo=Toolkit.getDefaultToolkit().createImage(
   *                   JR.getResources("logo.gif")
   *                   );
   *     ...
   * </pre>
   *
   * @param args arguments
   * @throws IOException
   */
  public static void main(String[] args)
      throws IOException {
    if (args.length != 2) {
      System.err.println(
          "usage: java JarResources <jar file name> <resource name>"
          );
      System.exit(1);
    }
    JarResources jr = new JarResources(args[0]);
    byte[] buff = jr.getResource(args[1]);
    if (buff == null) {
      System.out.println("Could not find " + args[1] + ".");
    }
    else {
      System.out.println("Found " + args[1] + " (length=" + buff.length + ").");
    }
  }
}