Java ByteBuffer Decode readInputStreamReader(InputStream in, ByteBuffer bytes, CharBuffer chars, CharsetDecoder decoder, Object lock)

Description

read Input Stream Reader

License

Apache License

Declaration

public static int readInputStreamReader(InputStream in, ByteBuffer bytes, CharBuffer chars,
            CharsetDecoder decoder, Object lock) throws IOException 

Method Source Code

//package com.java2s;
/*/*www. ja  v a 2  s.  c  o m*/
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

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

import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.CharsetDecoder;

import java.nio.charset.CoderResult;

public class Main {
    private static final int DEFAULT_BUFFER_SIZE = 8192;

    public static int readInputStreamReader(InputStream in, ByteBuffer bytes, CharBuffer chars,
            CharsetDecoder decoder, Object lock) throws IOException {
        synchronized (lock) {
            if (in != null) {
                if (chars.limit() == chars.position()) {
                    fillBuf(in, bytes, chars, decoder);
                }
                if (chars.limit() == 0) {
                    return -1;
                }
                return chars.get();
            }
            throw new IOException("InputStreamReader is closed");
        }
    }

    public static int readInputStreamReader(char[] buf, int offset, int length, InputStream in, ByteBuffer bytes,
            CharBuffer chars, CharsetDecoder decoder, Object lock) throws IOException {
        synchronized (lock) {
            if (in != null) {
                if (length == 0) {
                    return 0;
                }
                assertArrayIndex(buf.length, offset, length);
                // read at least once
                if (chars.limit() == chars.position()) {
                    fillBuf(in, bytes, chars, decoder);
                }
                int position = chars.position();
                int availableChars = chars.limit() - position;
                // read at least once for one byte
                int needChars = length;
                while (availableChars < needChars) {
                    System.arraycopy(chars.array(), position, buf, offset, availableChars);
                    chars.position(position + availableChars);
                    needChars -= availableChars;
                    offset += availableChars;
                    if (in.available() <= 0) {
                        return needChars == length ? -1 : length - needChars;
                    }
                    fillBuf(in, bytes, chars, decoder);
                    position = chars.position();
                    availableChars = chars.limit();
                    if (availableChars == 0) {
                        return needChars == length ? -1 : length - needChars;
                    }
                }
                System.arraycopy(chars.array(), position, buf, offset, needChars);
                chars.position(chars.position() + needChars);
                return length;
            }
            throw new IOException("InputStreamReader is closed");
        }
    }

    private static void fillBuf(InputStream in, ByteBuffer bytes, CharBuffer chars, CharsetDecoder decoder)
            throws IOException {
        chars.clear();
        int read = 0;
        try {
            read = in.read(bytes.array());
        } catch (IOException e) {
            chars.limit(0);
            throw e;
        }
        if (read == -1) {
            chars.limit(0);
            return;
        }
        bytes.limit(read);
        boolean endOfInput = read < DEFAULT_BUFFER_SIZE;
        CoderResult result = decoder.decode(bytes, chars, endOfInput);
        if (result.isError()) {
            throw new IOException(result.toString());
        }
        bytes.clear();
        chars.flip();
    }

    private static void assertArrayIndex(int arrayLength, int offset, int length) {
        if (offset < 0 || length < 0) {
            throw new IndexOutOfBoundsException("Negative index specified");
        }
        if ((long) offset + (long) length > arrayLength) {
            throw new IndexOutOfBoundsException("Size mismatch");
        }
    }
}

Related

1. decodeToString(ByteBuffer shaderInfoLogBuffer, IntBuffer size)
2. decodeUtf8(ByteBuffer bytes)
3. decodeUTF8(ByteBuffer utf8Data)
4. decodeUTF8(final ByteBuffer buf)
5. fillBuf(InputStream in, ByteBuffer bytes, CharBuffer chars, CharsetDecoder decoder)