IOUtils.java

/*
 * Copyright 2009 Sun Microsystems, Inc.  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.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

/**
 * IOUtils: A collection of IO-related public static methods.
 */

package sun.misc;

import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;

public class IOUtils {

    /**
     * Read up to <code>length</code> of bytes from <code>in</code>
     * until EOF is detected.
     * @param in input stream, must not be null
     * @param length number of bytes to read, -1 or Integer.MAX_VALUE means
     *        read as much as possible
     * @param readAll if true, an EOFException will be thrown if not enough
     *        bytes are read. Ignored when length is -1 or Integer.MAX_VALUE
     * @return bytes read
     * @throws IOException Any IO error or a premature EOF is detected
     */
    public static byte[] readFully(InputStream is, int length, boolean readAll)
            throws IOException {
        byte[] output = {};
        if (length == -1) length = Integer.MAX_VALUE;
        int pos = 0;
        while (pos < length) {
            int bytesToRead;
            if (pos >= output.length) { // Only expand when there's no room
                bytesToRead = Math.min(length - pos, output.length + 1024);
                if (output.length < pos + bytesToRead) {
                    output = Arrays.copyOf(output, pos + bytesToRead);
                }
            } else {
                bytesToRead = output.length - pos;
            }
            int cc = is.read(output, pos, bytesToRead);
            if (cc < 0) {
                if (readAll && length != Integer.MAX_VALUE) {
                    throw new EOFException("Detect premature EOF");
                } else {
                    if (output.length != pos) {
                        output = Arrays.copyOf(output, pos);
                    }
                    break;
                }
            }
            pos += cc;
        }
        return output;
    }
}