programming-examples/java/XML/JarInfo.java

JarInfo
  
 

package com.ack.tools.jarinfo;

// zip imports

import java.io.IOException;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.zip.ZipEntry;
import java.util.zip.ZipException;
import java.util.zip.ZipFile;

/**
 * Reads the header part of a zip/jar file and creates
 * an array of ZipEntry objects.  JarInfo also allows to
 * apply a filter to get the zip entries of their choice
 *
 * @see com.ack.tools.jarinfo.ZipEntryFilter
 */

public class JarInfo {
  private Hashtable fEntries;
  private String fZipFileName;

  /**
   * Use the JarInfoEntryFilter to selectively determine which
   * ZipEntries a JarInfo object should be comprised of.
   * @param the jar/zip file to interrogate
   * @exception is thrown if any errors occur trying read the
   *            the jar/zip file
   * @see com.ack.tools.jarinfo.ZipEntryFilter#accept
   */
  public JarInfo( String fileName, ZipEntryFilter filter ) throws JarInfoException {
    if( ( fZipFileName = fileName ) == null )
      throw new JarInfoException( "supplied filename to JarInfo was null" );

    if( filter == null )
      throw new JarInfoException( "supplied filter to JarInfo was null for archive ->"
                                  + fZipFileName );

    fEntries = new Hashtable();
    ZipFile zipFile = null;

    try {
      // create a ZipFile for the supplied 'fileName'
      zipFile = new ZipFile( fZipFileName );

      // cycle through the header information with the zipFile
      Enumeration e = zipFile.entries();
      while( e.hasMoreElements() ) {
        ZipEntry ze = (ZipEntry) e.nextElement();

        // if we have a filter for JarInfo, apply it
        if( filter.accept( ze ) == true )
          fEntries.put( ze.getName(), ze );
      }
    }
    catch( ZipException zipe ) {
      throw new JarInfoException( "Zip format problems reading " + fZipFileName + "\n"
                                  + zipe.getMessage() );
    }
    catch( IOException ioe ) {
      throw new JarInfoException( ioe.getMessage() );
    }
    catch( SecurityException se ) {
      throw new JarInfoException( "Security problems reading " + fZipFileName + "\n"
                                  + se.getMessage() );
    }
    finally {
      if( zipFile != null )
        try {
          zipFile.close();
        }
        catch( IOException ioe ) {
        }
    }
  }

  /**
   * accessor method to get the name of the jar
   * @return the jar/zip filename
   */
  public String zipFileName() {
    return fZipFileName;
  }

  /**
   * accessor method to get a handle on the ZipEntries for JarInfo
   * @return an Enumeration of the ZipEntries
   */
  public Enumeration zipEntries() {
    return fEntries.elements();
  }

  /**
   * accessor method to get a handle on the zip entries name for JarInfo
   * @return an Enumeration of the zip entries names
   */
  public Enumeration zipEntryNames() {
    return fEntries.keys();
  }

  /**
   * accessor method to get a handle on the zip entry hashtable
   * @return hashtable of zipEntryNames keys against zipEntry objects
   */
  public Hashtable zipEntryTable() {
    return fEntries;
  }

  /**
   * method to determine whether a resource is within JarInfo
   * @param the resource name to be checked
   * @return whether resource is a part of JarInfo
   */
  public boolean hasResource( String resource ) {
    if( resource != null )
      return fEntries.containsKey( resource );
    return false;
  }

  /**
   * accessor method to get a ZipEntry by name
   * @param the name for the entry
   * @return the ZipEntry if found, otherwise return null
   */
  public ZipEntry getZipEntry( String zipEntryName ) {
    ZipEntry entry = null;
    if( zipEntryName != null )
      entry = (ZipEntry) fEntries.get( zipEntryName );
    return entry;
  }

  /**
   * display the entries within JarInfo
   * @return entries collapsed into a single string
   */
  public String toString() {
    StringBuffer buf = new StringBuffer();
    Enumeration e = zipEntries();
    while( e.hasMoreElements() ) {
      ZipEntry ze = (ZipEntry) e.nextElement();
      buf.append( "\n**************************\n" );
      buf.append( "Zip Entry: " + ze.getName() + "\n" );
      buf.append( "Zip Date:  " + new java.util.Date( ze.getTime() ) + "\n" );
      buf.append( "Zip Size:  " + ze.getSize() + "\n" );
    }
    return buf.toString();
  }
}