1 /*
2 * Copyright 2012 The Netty Project
3 *
4 * The Netty Project licenses this file to you under the Apache License,
5 * version 2.0 (the "License"); you may not use this file except in compliance
6 * with the License. You may obtain a copy of the License at:
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13 * License for the specific language governing permissions and limitations
14 * under the License.
15 */
16 package io.netty.example.factorial;
17
18 import io.netty.channel.ChannelHandlerContext;
19 import io.netty.channel.SimpleChannelInboundHandler;
20
21 import java.math.BigInteger;
22
23 /**
24 * Handler for a server-side channel. This handler maintains stateful
25 * information which is specific to a certain channel using member variables.
26 * Therefore, an instance of this handler can cover only one channel. You have
27 * to create a new handler instance whenever you create a new channel and insert
28 * this handler to avoid a race condition.
29 */
30 public class FactorialServerHandler extends SimpleChannelInboundHandler<BigInteger> {
31
32 private BigInteger lastMultiplier = new BigInteger("1");
33 private BigInteger factorial = new BigInteger("1");
34
35 @Override
36 public void channelRead0(ChannelHandlerContext ctx, BigInteger msg) throws Exception {
37 // Calculate the cumulative factorial and send it to the client.
38 lastMultiplier = msg;
39 factorial = factorial.multiply(msg);
40 ctx.writeAndFlush(factorial);
41 }
42
43 @Override
44 public void channelInactive(ChannelHandlerContext ctx) throws Exception {
45 System.err.printf("Factorial of %,d is: %,d%n", lastMultiplier, factorial);
46 }
47
48 @Override
49 public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
50 cause.printStackTrace();
51 ctx.close();
52 }
53 }