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    1   /*
    2    * Copyright 2009 Red Hat, Inc.
    3    *
    4    * Red Hat licenses this file to you under the Apache License, version 2.0
    5    * (the "License"); you may not use this file except in compliance with the
    6    * 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 org.jboss.netty.example.factorial;
    17
    18  import java.math.BigInteger;
    19  import java.util.Formatter;
    20  import java.util.logging.Level;
    21  import java.util.logging.Logger;
    22
    23  import org.jboss.netty.channel.ChannelEvent;
    24  import org.jboss.netty.channel.ChannelHandlerContext;
    25  import org.jboss.netty.channel.ChannelStateEvent;
    26  import org.jboss.netty.channel.ExceptionEvent;
    27  import org.jboss.netty.channel.MessageEvent;
    28  import org.jboss.netty.channel.SimpleChannelUpstreamHandler;
    29
    30  /**
    31   * Handler for a server-side channel.  This handler maintains stateful
    32   * information which is specific to a certain channel using member variables.
    33   * Therefore, an instance of this handler can cover only one channel.  You have
    34   * to create a new handler instance whenever you create a new channel and insert
    35   * this handler  to avoid a race condition.
    36   *
    37   * @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
    38   * @author <a href="http://gleamynode.net/">Trustin Lee</a>
    39   *
    40   * @version $Rev: 2121 $, $Date: 2010-02-02 09:38:07 +0900 (Tue, 02 Feb 2010) $
    41   */
    42  public class FactorialServerHandler extends SimpleChannelUpstreamHandler {
    43
    44      private static final Logger logger = Logger.getLogger(
    45              FactorialServerHandler.class.getName());
    46
    47      // Stateful properties.
    48      private int lastMultiplier = 1;
    49      private BigInteger factorial = new BigInteger(new byte[] { 1 });
    50
    51      @Override
    52      public void handleUpstream(
    53              ChannelHandlerContext ctx, ChannelEvent e) throws Exception {
    54          if (e instanceof ChannelStateEvent) {
    55              logger.info(e.toString());
    56          }
    57          super.handleUpstream(ctx, e);
    58      }
    59
    60      @Override
    61      public void messageReceived(
    62              ChannelHandlerContext ctx, MessageEvent e) {
    63
    64          // Calculate the cumulative factorial and send it to the client.
    65          BigInteger number;
    66          if (e.getMessage() instanceof BigInteger) {
    67              number = (BigInteger) e.getMessage();
    68          } else {
    69              number = new BigInteger(e.getMessage().toString());
    70          }
    71          lastMultiplier = number.intValue();
    72          factorial = factorial.multiply(number);
    73          e.getChannel().write(factorial);
    74      }
    75
    76      @Override
    77      public void channelDisconnected(ChannelHandlerContext ctx,
    78              ChannelStateEvent e) throws Exception {
    79          logger.info(new Formatter().format(
    80                  "Factorial of %,d is: %,d", lastMultiplier, factorial).toString());
    81      }
    82
    83      @Override
    84      public void exceptionCaught(
    85              ChannelHandlerContext ctx, ExceptionEvent e) {
    86          logger.log(
    87                  Level.WARNING,
    88                  "Unexpected exception from downstream.",
    89                  e.getCause());
    90          e.getChannel().close();
    91      }
    92  }