Java tutorial
/* * 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 io.netty.util.internal.ObjectUtil; import java.io.InputStream; import java.io.PushbackInputStream; /** * A {@link ChunkedInput} that fetches data from an {@link InputStream} chunk by * chunk. * <p> * Please note that the {@link InputStream} instance that feeds data into * {@link ChunkedStream} must implement {@link InputStream#available()} as * accurately as possible, rather than using the default implementation. * Otherwise, {@link ChunkedStream} will generate many too small chunks or * block unnecessarily often. */ public class ChunkedStream implements ChunkedInput<ByteBuf> { static final int DEFAULT_CHUNK_SIZE = 8192; private final PushbackInputStream in; private final int chunkSize; private long offset; private boolean closed; /** * Creates a new instance that fetches data from the specified stream. */ public ChunkedStream(InputStream in) { this(in, DEFAULT_CHUNK_SIZE); } /** * Creates a new instance that fetches data from the specified stream. * * @param chunkSize the number of bytes to fetch on each * {@link #readChunk(ChannelHandlerContext)} call */ public ChunkedStream(InputStream in, int chunkSize) { ObjectUtil.checkNotNull(in, "in"); ObjectUtil.checkPositive(chunkSize, "chunkSize"); if (in instanceof PushbackInputStream) { this.in = (PushbackInputStream) in; } else { this.in = new PushbackInputStream(in); } this.chunkSize = chunkSize; } /** * Returns the number of transferred bytes. */ public long transferredBytes() { return offset; } @Override public boolean isEndOfInput() throws Exception { if (closed) { return true; } int b = in.read(); if (b < 0) { return true; } else { in.unread(b); return false; } } @Override public void close() throws Exception { closed = true; 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; } final int availableBytes = in.available(); final int chunkSize; if (availableBytes <= 0) { chunkSize = this.chunkSize; } else { chunkSize = Math.min(this.chunkSize, in.available()); } boolean release = true; ByteBuf buffer = allocator.buffer(chunkSize); try { // transfer to buffer offset += buffer.writeBytes(in, chunkSize); release = false; return buffer; } finally { if (release) { buffer.release(); } } } @Override public long length() { return -1; } @Override public long progress() { return offset; } }