Android Open Source - JiangHomeStyle_Android_Phone Zip Encoding Helper

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The source code is released under:

Apache License

Java Source Code

/*
 *  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
 */*from w ww  .j  ava 2  s  .  co  m*/
 *      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 org.apache.tools.zip;

import java.nio.ByteBuffer;
import java.nio.charset.Charset;
import java.nio.charset.UnsupportedCharsetException;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

/**
 * Static helper functions for robustly encoding filenames in zip files.
 */
public abstract class ZipEncodingHelper
{

  /**
   * A class, which holds the high characters of a simple encoding and lazily
   * instantiates a Simple8BitZipEncoding instance in a thread-safe manner.
   */
  private static class SimpleEncodingHolder
  {

    private final char[] highChars;
    private Simple8BitZipEncoding encoding;

    /**
     * Instantiate a simple encoding holder.
     * 
     * @param highChars
     *            The characters for byte codes 128 to 255.
     * 
     * @see Simple8BitZipEncoding#Simple8BitZipEncoding(char[])
     */
    SimpleEncodingHolder(char[] highChars)
    {
      this.highChars = highChars;
    }

    /**
     * @return The associated {@link Simple8BitZipEncoding}, which is
     *         instantiated if not done so far.
     */
    public synchronized Simple8BitZipEncoding getEncoding()
    {
      if (this.encoding == null)
      {
        this.encoding = new Simple8BitZipEncoding(this.highChars);
      }
      return this.encoding;
    }
  }

  private static final Map<String, SimpleEncodingHolder> simpleEncodings;

  static
  {
    Map<String, SimpleEncodingHolder> se = new HashMap<String, SimpleEncodingHolder>();

    char[] cp437_high_chars = new char[] { 0x00c7, 0x00fc, 0x00e9, 0x00e2, 0x00e4, 0x00e0, 0x00e5, 0x00e7, 0x00ea, 0x00eb,
        0x00e8, 0x00ef, 0x00ee, 0x00ec, 0x00c4, 0x00c5, 0x00c9, 0x00e6, 0x00c6, 0x00f4, 0x00f6, 0x00f2, 0x00fb, 0x00f9,
        0x00ff, 0x00d6, 0x00dc, 0x00a2, 0x00a3, 0x00a5, 0x20a7, 0x0192, 0x00e1, 0x00ed, 0x00f3, 0x00fa, 0x00f1, 0x00d1,
        0x00aa, 0x00ba, 0x00bf, 0x2310, 0x00ac, 0x00bd, 0x00bc, 0x00a1, 0x00ab, 0x00bb, 0x2591, 0x2592, 0x2593, 0x2502,
        0x2524, 0x2561, 0x2562, 0x2556, 0x2555, 0x2563, 0x2551, 0x2557, 0x255d, 0x255c, 0x255b, 0x2510, 0x2514, 0x2534,
        0x252c, 0x251c, 0x2500, 0x253c, 0x255e, 0x255f, 0x255a, 0x2554, 0x2569, 0x2566, 0x2560, 0x2550, 0x256c, 0x2567,
        0x2568, 0x2564, 0x2565, 0x2559, 0x2558, 0x2552, 0x2553, 0x256b, 0x256a, 0x2518, 0x250c, 0x2588, 0x2584, 0x258c,
        0x2590, 0x2580, 0x03b1, 0x00df, 0x0393, 0x03c0, 0x03a3, 0x03c3, 0x00b5, 0x03c4, 0x03a6, 0x0398, 0x03a9, 0x03b4,
        0x221e, 0x03c6, 0x03b5, 0x2229, 0x2261, 0x00b1, 0x2265, 0x2264, 0x2320, 0x2321, 0x00f7, 0x2248, 0x00b0, 0x2219,
        0x00b7, 0x221a, 0x207f, 0x00b2, 0x25a0, 0x00a0 };

    SimpleEncodingHolder cp437 = new SimpleEncodingHolder(cp437_high_chars);

    se.put("CP437", cp437);
    se.put("Cp437", cp437);
    se.put("cp437", cp437);
    se.put("IBM437", cp437);
    se.put("ibm437", cp437);

    char[] cp850_high_chars = new char[] { 0x00c7, 0x00fc, 0x00e9, 0x00e2, 0x00e4, 0x00e0, 0x00e5, 0x00e7, 0x00ea, 0x00eb,
        0x00e8, 0x00ef, 0x00ee, 0x00ec, 0x00c4, 0x00c5, 0x00c9, 0x00e6, 0x00c6, 0x00f4, 0x00f6, 0x00f2, 0x00fb, 0x00f9,
        0x00ff, 0x00d6, 0x00dc, 0x00f8, 0x00a3, 0x00d8, 0x00d7, 0x0192, 0x00e1, 0x00ed, 0x00f3, 0x00fa, 0x00f1, 0x00d1,
        0x00aa, 0x00ba, 0x00bf, 0x00ae, 0x00ac, 0x00bd, 0x00bc, 0x00a1, 0x00ab, 0x00bb, 0x2591, 0x2592, 0x2593, 0x2502,
        0x2524, 0x00c1, 0x00c2, 0x00c0, 0x00a9, 0x2563, 0x2551, 0x2557, 0x255d, 0x00a2, 0x00a5, 0x2510, 0x2514, 0x2534,
        0x252c, 0x251c, 0x2500, 0x253c, 0x00e3, 0x00c3, 0x255a, 0x2554, 0x2569, 0x2566, 0x2560, 0x2550, 0x256c, 0x00a4,
        0x00f0, 0x00d0, 0x00ca, 0x00cb, 0x00c8, 0x0131, 0x00cd, 0x00ce, 0x00cf, 0x2518, 0x250c, 0x2588, 0x2584, 0x00a6,
        0x00cc, 0x2580, 0x00d3, 0x00df, 0x00d4, 0x00d2, 0x00f5, 0x00d5, 0x00b5, 0x00fe, 0x00de, 0x00da, 0x00db, 0x00d9,
        0x00fd, 0x00dd, 0x00af, 0x00b4, 0x00ad, 0x00b1, 0x2017, 0x00be, 0x00b6, 0x00a7, 0x00f7, 0x00b8, 0x00b0, 0x00a8,
        0x00b7, 0x00b9, 0x00b3, 0x00b2, 0x25a0, 0x00a0 };

    SimpleEncodingHolder cp850 = new SimpleEncodingHolder(cp850_high_chars);

    se.put("CP850", cp850);
    se.put("Cp850", cp850);
    se.put("cp850", cp850);
    se.put("IBM850", cp850);
    se.put("ibm850", cp850);
    simpleEncodings = Collections.unmodifiableMap(se);
  }

  /**
   * Grow a byte buffer, so it has a minimal capacity or at least the double
   * capacity of the original buffer
   * 
   * @param b
   *            The original buffer.
   * @param newCapacity
   *            The minimal requested new capacity.
   * @return A byte buffer <code>r</code> with
   *         <code>r.capacity() = max(b.capacity()*2,newCapacity)</code> and
   *         all the data contained in <code>b</code> copied to the beginning
   *         of <code>r</code>.
   * 
   */
  static ByteBuffer growBuffer(ByteBuffer b, int newCapacity)
  {
    b.limit(b.position());
    b.rewind();

    int c2 = b.capacity() * 2;
    ByteBuffer on = ByteBuffer.allocate(c2 < newCapacity ? newCapacity : c2);

    on.put(b);
    return on;
  }

  /**
   * The hexadecimal digits <code>0,...,9,A,...,F</code> encoded as ASCII
   * bytes.
   */
  private static final byte[] HEX_DIGITS = new byte[] { 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x41, 0x42,
      0x43, 0x44, 0x45, 0x46 };

  /**
   * Append <code>%Uxxxx</code> to the given byte buffer. The caller must
   * assure, that <code>bb.remaining()&gt;=6</code>.
   * 
   * @param bb
   *            The byte buffer to write to.
   * @param c
   *            The character to write.
   */
  static void appendSurrogate(ByteBuffer bb, char c)
  {

    bb.put((byte) '%');
    bb.put((byte) 'U');

    bb.put(HEX_DIGITS[(c >> 12) & 0x0f]);
    bb.put(HEX_DIGITS[(c >> 8) & 0x0f]);
    bb.put(HEX_DIGITS[(c >> 4) & 0x0f]);
    bb.put(HEX_DIGITS[c & 0x0f]);
  }

  /**
   * name of the encoding UTF-8
   */
  static final String UTF8 = "UTF8";

  /**
   * variant name of the encoding UTF-8 used for comparisions.
   */
  private static final String UTF_DASH_8 = "utf-8";

  /**
   * name of the encoding UTF-8
   */
  static final ZipEncoding UTF8_ZIP_ENCODING = new FallbackZipEncoding(UTF8);

  /**
   * Instantiates a zip encoding.
   * 
   * @param name
   *            The name of the zip encoding. Specify {@code null} for the
   *            platform's default encoding.
   * @return A zip encoding for the given encoding name.
   */
  public static ZipEncoding getZipEncoding(String name)
  {

    // fallback encoding is good enough for utf-8.
    if (isUTF8(name))
    {
      return UTF8_ZIP_ENCODING;
    }

    if (name == null)
    {
      return new FallbackZipEncoding();
    }

    SimpleEncodingHolder h = simpleEncodings.get(name);

    if (h != null)
    {
      return h.getEncoding();
    }

    try
    {

      Charset cs = Charset.forName(name);
      return new NioZipEncoding(cs);

    }
    catch (UnsupportedCharsetException e)
    {
      return new FallbackZipEncoding(name);
    }
  }

  /**
   * Whether a given encoding - or the platform's default encoding if the
   * parameter is null - is UTF-8.
   */
  static boolean isUTF8(String encoding)
  {
    if (encoding == null)
    {
      // check platform's default encoding
      encoding = System.getProperty("file.encoding");
    }
    return UTF8.equalsIgnoreCase(encoding) || UTF_DASH_8.equalsIgnoreCase(encoding);
  }
}

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