Quadcap Embeddable Server

com/quadcap/io/Base64InputStream.java

Go to the documentation of this file.

package com.quadcap.io;

/* Copyright 1997 - 2003 Quadcap Software.  All rights reserved.
 *
 * This software is distributed under the Quadcap Free Software License.
 * This software may be used or modified for any purpose, personal or
 * commercial.  Open Source redistributions are permitted.  Commercial
 * redistribution of larger works derived from, or works which bundle
 * this software requires a "Commercial Redistribution License"; see
 * http://www.quadcap.com/purchase.
 *
 * Redistributions qualify as "Open Source" under  one of the following terms:
 *   
 *    Redistributions are made at no charge beyond the reasonable cost of
 *    materials and delivery.
 *
 *    Redistributions are accompanied by a copy of the Source Code or by an
 *    irrevocable offer to provide a copy of the Source Code for up to three
 *    years at the cost of materials and delivery.  Such redistributions
 *    must allow further use, modification, and redistribution of the Source
 *    Code under substantially the same terms as this license.
 *
 * Redistributions of source code must retain the copyright notices as they
 * appear in each source code file, these license terms, and the
 * disclaimer/limitation of liability set forth as paragraph 6 below.
 *
 * Redistributions in binary form must reproduce this Copyright Notice,
 * these license terms, and the disclaimer/limitation of liability set
 * forth as paragraph 6 below, in the documentation and/or other materials
 * provided with the distribution.
 *
 * The Software is provided on an "AS IS" basis.  No warranty is
 * provided that the Software is free of defects, or fit for a
 * particular purpose.  
 *
 * Limitation of Liability. Quadcap Software shall not be liable
 * for any damages suffered by the Licensee or any third party resulting
 * from use of the Software.
 */

import java.io.InputStream;
import java.io.IOException;

/**
 * 
 *
 * @author Stan Bailes
 */
public class Base64InputStream extends InputStream {
    InputStream                 in;
    int                         accum   = 0;
    int                         cnt     = -1;
    boolean                     eof     = false;

    static int[] base64Map      = new int[256];
    static {
        byte[] b = Base64OutputStream.base64;
        for (int i = 0; i < base64Map.length; i++) base64Map[i] = -1;
        for (int i = 0; i < b.length; i++) {
            base64Map[b[i]] = i;
        }
        base64Map['='] = 0;
    }

    public Base64InputStream(InputStream in) {
        this.in = in;
    }

    final int readChar() throws IOException {
        int c = eof ? -1 : in.read();
        while (c == '\r' || c == '\n') c = in.read();
        eof = c < 0;
        return c;
    }

    public int read() throws IOException {
        if (eof) return -1;
        if (cnt < 0) {
            int c1 = readChar();
            int c2 = readChar();
            int c3 = readChar();
            int c4 = readChar();
//          System.out.println("[" + (char)c1 + "] [" + (char)c2 + "] [" + (char)c3 +
//                             "] [" + (char)c4 + "]");
            if (eof) return -1;

            int b1 = base64Map[c1];
            int b2 = base64Map[c2];
            int b3 = base64Map[c3];
            int b4 = base64Map[c4];

//          System.out.println("(" + b1 + ") (" + b2 + ") (" + b3 + ") (" + b4 + ")");
            if (b1 < 0 || b2 < 0 || b3 < 0 || b4 < 0) {
                throw new IOException("Bad base64 character");
            }
            accum = (b1 << 18) | (b2 << 12) | (b3 << 6) | b4;
//          System.out.println(Integer.toHexString(accum));

            if (c3 == '=') {
                cnt = 0;
                accum >>= 16;
            } else if (c4 == '=') {
                cnt = 8;
                accum >>= 8;
            } else {
                cnt = 16;
            }
                
        }
        int ret = (accum >> cnt) & 0xff;
        cnt -= 8;
        return ret;
    }

    public void close() throws IOException {
        in.close();
    }
}