Java example source code file (ZipCoder.java)

This example Java source code file (ZipCoder.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

arraydecoder, arrayencoder, bytebuffer, charbuffer, charsetdecoder, charsetencoder, coderresult, illegalargumentexception, malformed, nio, string, util, zipcoder

The ZipCoder.java Java example source code

/*
 * Copyright (c) 2009, 2011, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package java.util.zip;

import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CharsetEncoder;
import java.nio.charset.CoderResult;
import java.nio.charset.CodingErrorAction;
import java.util.Arrays;
import sun.nio.cs.ArrayDecoder;
import sun.nio.cs.ArrayEncoder;

/**
 * Utility class for zipfile name and comment decoding and encoding
 */

final class ZipCoder {

    String toString(byte[] ba, int length) {
        CharsetDecoder cd = decoder().reset();
        int len = (int)(length * cd.maxCharsPerByte());
        char[] ca = new char[len];
        if (len == 0)
            return new String(ca);
        // UTF-8 only for now. Other ArrayDeocder only handles
        // CodingErrorAction.REPLACE mode. ZipCoder uses
        // REPORT mode.
        if (isUTF8 && cd instanceof ArrayDecoder) {
            int clen = ((ArrayDecoder)cd).decode(ba, 0, length, ca);
            if (clen == -1)    // malformed
                throw new IllegalArgumentException("MALFORMED");
            return new String(ca, 0, clen);
        }
        ByteBuffer bb = ByteBuffer.wrap(ba, 0, length);
        CharBuffer cb = CharBuffer.wrap(ca);
        CoderResult cr = cd.decode(bb, cb, true);
        if (!cr.isUnderflow())
            throw new IllegalArgumentException(cr.toString());
        cr = cd.flush(cb);
        if (!cr.isUnderflow())
            throw new IllegalArgumentException(cr.toString());
        return new String(ca, 0, cb.position());
    }

    String toString(byte[] ba) {
        return toString(ba, ba.length);
    }

    byte[] getBytes(String s) {
        CharsetEncoder ce = encoder().reset();
        char[] ca = s.toCharArray();
        int len = (int)(ca.length * ce.maxBytesPerChar());
        byte[] ba = new byte[len];
        if (len == 0)
            return ba;
        // UTF-8 only for now. Other ArrayDeocder only handles
        // CodingErrorAction.REPLACE mode.
        if (isUTF8 && ce instanceof ArrayEncoder) {
            int blen = ((ArrayEncoder)ce).encode(ca, 0, ca.length, ba);
            if (blen == -1)    // malformed
                throw new IllegalArgumentException("MALFORMED");
            return Arrays.copyOf(ba, blen);
        }
        ByteBuffer bb = ByteBuffer.wrap(ba);
        CharBuffer cb = CharBuffer.wrap(ca);
        CoderResult cr = ce.encode(cb, bb, true);
        if (!cr.isUnderflow())
            throw new IllegalArgumentException(cr.toString());
        cr = ce.flush(bb);
        if (!cr.isUnderflow())
            throw new IllegalArgumentException(cr.toString());
        if (bb.position() == ba.length)  // defensive copy?
            return ba;
        else
            return Arrays.copyOf(ba, bb.position());
    }

    // assume invoked only if "this" is not utf8
    byte[] getBytesUTF8(String s) {
        if (isUTF8)
            return getBytes(s);
        if (utf8 == null)
            utf8 = new ZipCoder(StandardCharsets.UTF_8);
        return utf8.getBytes(s);
    }


    String toStringUTF8(byte[] ba, int len) {
        if (isUTF8)
            return toString(ba, len);
        if (utf8 == null)
            utf8 = new ZipCoder(StandardCharsets.UTF_8);
        return utf8.toString(ba, len);
    }

    boolean isUTF8() {
        return isUTF8;
    }

    private Charset cs;
    private CharsetDecoder dec;
    private CharsetEncoder enc;
    private boolean isUTF8;
    private ZipCoder utf8;

    private ZipCoder(Charset cs) {
        this.cs = cs;
        this.isUTF8 = cs.name().equals(StandardCharsets.UTF_8.name());
    }

    static ZipCoder get(Charset charset) {
        return new ZipCoder(charset);
    }

    private CharsetDecoder decoder() {
        if (dec == null) {
            dec = cs.newDecoder()
              .onMalformedInput(CodingErrorAction.REPORT)
              .onUnmappableCharacter(CodingErrorAction.REPORT);
        }
        return dec;
    }

    private CharsetEncoder encoder() {
        if (enc == null) {
            enc = cs.newEncoder()
              .onMalformedInput(CodingErrorAction.REPORT)
              .onUnmappableCharacter(CodingErrorAction.REPORT);
        }
        return enc;
    }
}