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.ChannelHandlerContext; import io.netty.channel.SimpleChannelInboundHandler; import java.math.BigInteger; /** * * Handler for a server-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 FactorialServerHandler extends SimpleChannelInboundHandler<BigInteger> { private BigInteger lastMultiplier = new BigInteger("1"); private BigInteger factorial = new BigInteger("1"); @Override public void messageReceived(ChannelHandlerContext ctx, BigInteger msg) { // Calculate the cumulative factorial and send it to the client. lastMultiplier = msg; factorial = factorial.multiply(msg); ctx.writeAndFlush(factorial); } @Override public void channelInactive(ChannelHandlerContext ctx) throws Exception { System.err.printf("Factorial of %,d is: %,d%n", lastMultiplier, factorial); } @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { cause.printStackTrace(); ctx.close(); } }