Java tutorial
/* * 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 * * 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.commons.compress.archivers.zip; import java.nio.ByteBuffer; import java.nio.charset.Charset; import java.nio.charset.UnsupportedCharsetException; import java.util.HashMap; import java.util.Map; /** * Static helper functions for robustly encoding filenames in zip files. */ 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 simpleEncodings; static { simpleEncodings = new HashMap(); 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); simpleEncodings.put("CP437", cp437); simpleEncodings.put("Cp437", cp437); simpleEncodings.put("cp437", cp437); simpleEncodings.put("IBM437", cp437); simpleEncodings.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); simpleEncodings.put("CP850", cp850); simpleEncodings.put("Cp850", cp850); simpleEncodings.put("cp850", cp850); simpleEncodings.put("IBM850", cp850); simpleEncodings.put("ibm850", cp850); } /** * 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()>=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</code> for * the platform's default encoding. * @return A zip encoding for the given encoding name. */ 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 = (SimpleEncodingHolder) 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); } }