stringinputstream.java

一個Light Weighted的Java Database Engin 適合各個領域之Java數据庫編輯.

/* Copyright (c) 2001-2005, The HSQL Development Group
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of the HSQL Development Group nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG,
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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 */


package org.hsqldb.lib;

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

/**
 * minimal InputStream subclass to fetch bytes form a String
 *
 * @author fredt@users
 * @version 1.7.0
 */
public class StringInputStream extends InputStream {

    protected int    strOffset  = 0;
    protected int    charOffset = 0;
    protected int    available;
    protected String str;

    public StringInputStream(String s) {
        str       = s;
        available = s.length() * 2;
    }

    public int read() throws java.io.IOException {

        if (available == 0) {
            return -1;
        }

        available--;

        char c = str.charAt(strOffset);

        if (charOffset == 0) {
            charOffset = 1;

            return (c & 0x0000ff00) >> 8;
        } else {
            charOffset = 0;

            strOffset++;

            return c & 0x000000ff;
        }
    }

    public int available() throws IOException {
        return available;
    }
}