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 com.dwarf.netty.guide.factorial; import io.netty.channel.ChannelFuture; import io.netty.channel.ChannelFutureListener; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.SimpleChannelInboundHandler; import java.math.BigInteger; import java.util.concurrent.BlockingQueue; import java.util.concurrent.LinkedBlockingQueue; /** * Handler for a client-side channel. This handler maintains stateful * information which is specific to a certain channel using member variables. * Therefore, an instance of this handler can cover only one channel. You have * to create a new handler instance whenever you create a new channel and insert * this handler to avoid a race condition. */ public class FactorialClientHandler extends SimpleChannelInboundHandler<BigInteger> { private ChannelHandlerContext ctx; private int receivedMessages; private int next = 1; final BlockingQueue<BigInteger> answer = new LinkedBlockingQueue<BigInteger>(); public BigInteger getFactorial() { boolean interrupted = false; try { for (;;) { try { return answer.take(); } catch (InterruptedException ignore) { interrupted = true; } } } finally { if (interrupted) { Thread.currentThread().interrupt(); } } } @Override public void channelActive(ChannelHandlerContext ctx) { this.ctx = ctx; sendNumbers(); } @Override public void messageReceived(ChannelHandlerContext ctx, final BigInteger msg) { receivedMessages++; if (receivedMessages == FactorialClient.COUNT) { // Offer the answer after closing the connection. ctx.channel().close().addListener(new ChannelFutureListener() { @Override public void operationComplete(ChannelFuture future) { boolean offered = answer.offer(msg); assert offered; } }); } } @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) { cause.printStackTrace(); ctx.close(); } private void sendNumbers() { // Do not send more than 4096 numbers. ChannelFuture future = null; for (int i = 0; i < 4096 && next <= FactorialClient.COUNT; i++) { future = ctx.write(Integer.valueOf(next)); next++; } if (next <= FactorialClient.COUNT) { assert future != null; future.addListener(numberSender); } ctx.flush(); } private final ChannelFutureListener numberSender = new ChannelFutureListener() { @Override public void operationComplete(ChannelFuture future) throws Exception { if (future.isSuccess()) { sendNumbers(); } else { future.cause().printStackTrace(); future.channel().close(); } } }; }