Reads an UTF8 string from a byte buffer. - Java java.nio

Java examples for java.nio:ByteBuffer Read

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Description

Reads an UTF8 string from a byte buffer.

Demo Code

/*/*from ww  w .j av a  2  s.  com*/
 * This file is part of Flow Networking, licensed under the MIT License (MIT).
 *
 * Copyright (c) 2013 Spout LLC <http://www.spout.org/>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
//package com.java2s;
import java.io.DataInput;

import java.io.IOException;
import java.nio.charset.StandardCharsets;

public class Main {
    /**
     * Reads an UTF8 string from a byte buffer.
     *
     * @param buf The byte buffer to read from
     * @return The read string
     * @throws java.io.IOException If the reading fails
     */
    public static String readUTF8(DataInput buf) throws IOException {
        // Read the string's length
        final int len = readVarInt(buf);
        final byte[] bytes = new byte[len];
        buf.readFully(bytes);
        return new String(bytes, StandardCharsets.UTF_8);
    }

    /**
     * Reads an integer written into the byte buffer as one of various bit sizes.
     *
     * @param buf The byte buffer to read from
     * @return The read integer
     * @throws java.io.IOException If the reading fails
     */
    public static int readVarInt(DataInput buf) throws IOException {
        int out = 0;
        int bytes = 0;
        byte in;
        while (true) {
            in = buf.readByte();
            out |= (in & 0x7F) << (bytes * 7);
            if (bytes > 32) {
                throw new IOException(
                        "Attempt to read int bigger than allowed for a varint!");
            }
            if ((in & 0x80) != 0x80) {
                break;
            }
        }
        return out;
    }
}

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