com.github.liyp.rabbitmq.rpc.RPCServer.java Source code

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Here is the source code for com.github.liyp.rabbitmq.rpc.RPCServer.java

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/*
 * Copyright  2017 liyp (liyp.yunpeng@gmail.com)
 *
 * Licensed 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.
 */
/**
 * http://www.rabbitmq.com/tutorials/tutorial-six-java.html
 */

package com.github.liyp.rabbitmq.rpc;

import com.rabbitmq.client.ConnectionFactory;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.QueueingConsumer;
import com.rabbitmq.client.AMQP.BasicProperties;

public class RPCServer {

    private static final String RPC_QUEUE_NAME = "rpc_queue";

    private static int fib(int n) {
        if (n == 0)
            return 0;
        if (n == 1)
            return 1;
        return fib(n - 1) + fib(n - 2);
    }

    public static void main(String[] argv) {
        Connection connection = null;
        Channel channel = null;
        try {
            ConnectionFactory factory = new ConnectionFactory();
            factory.setHost("localhost");

            connection = factory.newConnection();
            channel = connection.createChannel();

            channel.queueDeclare(RPC_QUEUE_NAME, false, false, false, null);

            channel.basicQos(1);

            QueueingConsumer consumer = new QueueingConsumer(channel);
            channel.basicConsume(RPC_QUEUE_NAME, false, consumer);

            System.out.println(" [x] Awaiting RPC requests");

            while (true) {
                String response = null;

                QueueingConsumer.Delivery delivery = consumer.nextDelivery();

                BasicProperties props = delivery.getProperties();
                BasicProperties replyProps = new BasicProperties.Builder().correlationId(props.getCorrelationId())
                        .build();

                try {
                    String message = new String(delivery.getBody(), "UTF-8");
                    int n = Integer.parseInt(message);

                    System.out.println(" [.] fib(" + message + ")");
                    response = "" + fib(n);
                } catch (Exception e) {
                    System.out.println(" [.] " + e.toString());
                    response = "";
                } finally {
                    channel.basicPublish("", props.getReplyTo(), replyProps, response.getBytes("UTF-8"));

                    channel.basicAck(delivery.getEnvelope().getDeliveryTag(), false);
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (connection != null) {
                try {
                    connection.close();
                } catch (Exception ignore) {
                }
            }
        }
    }
}