ZipConstants.java

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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,
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 *
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package java.util.zip;

/**
 * This interface defines the constants that are used by the classes which manipulate ZIP files.
 *
 * @author      David Connelly
 * @since 1.1
 */
/*
 * zip文件格式常量
 *
 * 参见：https://pkware.cachefly.net/webdocs/APPNOTE/APPNOTE-6.3.5.TXT
 */
interface ZipConstants {
    /*
     * Header signatures
     */
    static long LOCSIG = 0x04034b50L;   // "PK\003\004" | 文件头标识(属于zip文件的第一部分的第1小节)，该值固定
    static long EXTSIG = 0x08074b50L;   // "PK\007\008" | 扩展数据描述符起始标记(属于zip文件的第一部分的第3小节)
    static long CENSIG = 0x02014b50L;   // "PK\001\002" | 核心目录文件头标识(zip文件的第二部分)
    static long ENDSIG = 0x06054b50L;   // "PK\005\006" | 核心目录结束标记(zip文件的第三部分)
    
    /*
     * Header sizes in bytes (including signatures)
     */
    static final int LOCHDR = 30;       // LOC header size
    static final int EXTHDR = 16;       // EXT header size
    static final int CENHDR = 46;       // CEN header size
    static final int ENDHDR = 22;       // END header size
    
    /*
     * Local file (LOC) header field offsets
     */
    static final int LOCVER = 4;        // version needed to extract
    static final int LOCFLG = 6;        // general purpose bit flag
    static final int LOCHOW = 8;        // compression method
    static final int LOCTIM = 10;       // modification time
    static final int LOCCRC = 14;       // uncompressed file crc-32 value
    static final int LOCSIZ = 18;       // compressed size
    static final int LOCLEN = 22;       // uncompressed size
    static final int LOCNAM = 26;       // filename length
    static final int LOCEXT = 28;       // extra field length
    
    /*
     * Extra local (EXT) header field offsets
     */
    static final int EXTCRC = 4;        // uncompressed file crc-32 value
    static final int EXTSIZ = 8;        // compressed size
    static final int EXTLEN = 12;       // uncompressed size
    
    /*
     * Central directory (CEN) header field offsets
     */
    static final int CENVEM = 4;        // version made by
    static final int CENVER = 6;        // version needed to extract
    static final int CENFLG = 8;        // encrypt, decrypt flags
    static final int CENHOW = 10;       // compression method
    static final int CENTIM = 12;       // modification time
    static final int CENCRC = 16;       // uncompressed file crc-32 value
    static final int CENSIZ = 20;       // compressed size
    static final int CENLEN = 24;       // uncompressed size
    static final int CENNAM = 28;       // filename length
    static final int CENEXT = 30;       // extra field length
    static final int CENCOM = 32;       // comment length
    static final int CENDSK = 34;       // disk number start
    static final int CENATT = 36;       // internal file attributes
    static final int CENATX = 38;       // external file attributes
    static final int CENOFF = 42;       // LOC header offset
    
    /*
     * End of central directory (END) header field offsets
     */
    static final int ENDSUB = 8;        // number of entries on this disk
    static final int ENDTOT = 10;       // total number of entries
    static final int ENDSIZ = 12;       // central directory size in bytes
    static final int ENDOFF = 16;       // offset of first CEN header
    static final int ENDCOM = 20;       // zip file comment length
}