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Java example source code file (ChunkedNioStream.java)

This example Java source code file (ChunkedNioStream.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

bytebuf, bytebuffer, chunkedinput, chunkedniostream, deprecated, exception, illegalargumentexception, nio, nullpointerexception, override, readablebytechannel

The ChunkedNioStream.java Java example source code

/*
 * Copyright 2012 The Netty Project
 *
 * The Netty Project 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.
 */
package io.netty.handler.stream;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.ByteBufAllocator;
import io.netty.channel.ChannelHandlerContext;

import java.nio.ByteBuffer;
import java.nio.channels.ReadableByteChannel;

/**
 * A {@link ChunkedInput} that fetches data from a {@link ReadableByteChannel}
 * chunk by chunk.  Please note that the {@link ReadableByteChannel} must
 * operate in blocking mode.  Non-blocking mode channels are not supported.
 */
public class ChunkedNioStream implements ChunkedInput<ByteBuf> {

    private final ReadableByteChannel in;

    private final int chunkSize;
    private long offset;

    /**
     * Associated ByteBuffer
     */
    private final ByteBuffer byteBuffer;

    /**
     * Creates a new instance that fetches data from the specified channel.
     */
    public ChunkedNioStream(ReadableByteChannel in) {
        this(in, ChunkedStream.DEFAULT_CHUNK_SIZE);
    }

    /**
     * Creates a new instance that fetches data from the specified channel.
     *
     * @param chunkSize the number of bytes to fetch on each
     *                  {@link #readChunk(ChannelHandlerContext)} call
     */
    public ChunkedNioStream(ReadableByteChannel in, int chunkSize) {
        if (in == null) {
            throw new NullPointerException("in");
        }
        if (chunkSize <= 0) {
            throw new IllegalArgumentException("chunkSize: " + chunkSize +
                    " (expected: a positive integer)");
        }
        this.in = in;
        offset = 0;
        this.chunkSize = chunkSize;
        byteBuffer = ByteBuffer.allocate(chunkSize);
    }

    /**
     * Returns the number of transferred bytes.
     */
    public long transferredBytes() {
        return offset;
    }

    @Override
    public boolean isEndOfInput() throws Exception {
        if (byteBuffer.position() > 0) {
            // A previous read was not over, so there is a next chunk in the buffer at least
            return false;
        }
        if (in.isOpen()) {
            // Try to read a new part, and keep this part (no rewind)
            int b = in.read(byteBuffer);
            if (b < 0) {
                return true;
            } else {
                offset += b;
                return false;
            }
        }
        return true;
    }

    @Override
    public void close() throws Exception {
        in.close();
    }

    @Deprecated
    @Override
    public ByteBuf readChunk(ChannelHandlerContext ctx) throws Exception {
        return readChunk(ctx.alloc());
    }

    @Override
    public ByteBuf readChunk(ByteBufAllocator allocator) throws Exception {
        if (isEndOfInput()) {
            return null;
        }
        // buffer cannot be not be empty from there
        int readBytes = byteBuffer.position();
        for (;;) {
            int localReadBytes = in.read(byteBuffer);
            if (localReadBytes < 0) {
                break;
            }
            readBytes += localReadBytes;
            offset += localReadBytes;
            if (readBytes == chunkSize) {
                break;
            }
        }
        byteBuffer.flip();
        boolean release = true;
        ByteBuf buffer = allocator.buffer(byteBuffer.remaining());
        try {
            buffer.writeBytes(byteBuffer);
            byteBuffer.clear();
            release = false;
            return buffer;
        } finally {
            if (release) {
                buffer.release();
            }
        }
    }

    @Override
    public long length() {
        return -1;
    }

    @Override
    public long progress() {
        return offset;
    }
}

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