Java tutorial
/* * Copyright (c) 2016, WSO2 Inc. (http://www.wso2.org) All Rights Reserved. * * WSO2 Inc. 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 org.wso2.carbon.event.adapter.rabbitmq.internal.util; import com.rabbitmq.client.Channel; import com.rabbitmq.client.Connection; import com.rabbitmq.client.ConnectionFactory; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.wso2.carbon.event.adapter.rabbitmq.internal.exception.RabbitAdapterMQException; import java.io.IOException; import java.util.concurrent.TimeoutException; /** * This class represents making connection by specifying queue and exchange to RabbtMQ broker. */ public class RabbitMQEventAdapterUtils { private static final Log log = LogFactory.getLog(RabbitMQEventAdapterUtils.class); /** * Creating Connection to the rabbitMQ broker * * @param factory Object of connection Factory class. * @throws IOException */ public static Connection createConnection(ConnectionFactory factory) throws IOException, TimeoutException { return factory.newConnection(); } /** * This specifies whether the queue should remain declared even if the broker restarts. * * @param isDurable True or false value determining queue is durable or not. */ public static boolean isDurableQueue(String isDurable) { return !(isDurable != null && !isDurable.equals("")) || Boolean.parseBoolean(isDurable); } /** * This specifies whether the queue should be exclusive to one connection or whether it should be consumable by * other connections. * * @param isExclusive True or false value determining queue is exclusive or not. */ public static boolean isExclusiveQueue(String isExclusive) { return isExclusive != null && !isExclusive.equals("") && Boolean.parseBoolean(isExclusive); } /** * This specifies whether the queue should be kept even if it is not being consumed anymore. * * @param isAutoDelete True or false value determining queue is auto delete or not. */ public static boolean isAutoDeleteQueue(String isAutoDelete) { return isAutoDelete != null && !isAutoDelete.equals("") && Boolean.parseBoolean(isAutoDelete); } /** * Check Whether Queue is available * * @param connection Connection to the RabbitMQ * @param queueName Name of the queue */ public static boolean isQueueAvailable(Connection connection, String queueName) throws IOException { Channel channel = connection.createChannel(); try { // check availability of the named queue // if an error is encountered, including if the queue does not exist and if the // queue is exclusively owned by another connection channel.queueDeclarePassive(queueName); return true; } catch (IOException e) { return false; } } /** * @param connection Connection to the RabbitMQ * @param queueName Name of the queue * @param isDurable Whether durable or not * @param isExclusive Whether exclusive or not * @param isAutoDelete Whether queue is auto delete or not * @throws IOException */ public static void declareQueue(Connection connection, String queueName, String isDurable, String isExclusive, String isAutoDelete) throws IOException { boolean queueAvailable = isQueueAvailable(connection, queueName); Channel channel = connection.createChannel(); if (!queueAvailable) { if (log.isDebugEnabled()) { log.debug("Queue :" + queueName + " not found or already declared exclusive. Declaring the queue."); } // Declare the named queue if it does not exists. if (!channel.isOpen()) { channel = connection.createChannel(); log.debug("Channel is not open. Creating a new channel."); } try { channel.queueDeclare(queueName, isDurableQueue(isDurable), isExclusiveQueue(isExclusive), isAutoDeleteQueue(isAutoDelete), null); } catch (IOException e) { handleException("Error while creating queue: " + queueName, e); } } } /** * @param connection Connection to the RabbitMQ * @param exchangeName Name of the exchange * @param exchangeType Type of Exchange * @param exchangeDurable Whether durable or not * @throws IOException */ public static void declareExchange(Connection connection, String exchangeName, String exchangeType, String exchangeDurable) throws IOException, TimeoutException { Boolean exchangeAvailable = false; Channel channel = connection.createChannel(); try { // check availability of the named exchange. // The server will raise an IOException if the named exchange already exists. channel.exchangeDeclarePassive(exchangeName); exchangeAvailable = true; } catch (IOException e) { log.info("Exchange :" + exchangeName + " not found.Declaring exchange."); } if (!exchangeAvailable) { // Declare the named exchange if it does not exists. if (!channel.isOpen()) { channel = connection.createChannel(); log.debug("Channel is not open. Creating a new channel."); } try { if (exchangeType != null && !exchangeType.equals("")) { if (exchangeDurable != null && !exchangeDurable.equals("")) { channel.exchangeDeclare(exchangeName, exchangeType, Boolean.parseBoolean(exchangeDurable)); } else { channel.exchangeDeclare(exchangeName, exchangeType, true); } } else { channel.exchangeDeclare(exchangeName, RabbitMQInputEventAdapterConstants.DEFAULT_EXCHANGE_TYPE, true); } } catch (IOException e) { handleException("Error occurred while declaring exchange.", e); } } channel.close(); } /** * Handle the exception by throwing the exception * * @param msg Error message of the exception. * @param e Exception Object */ public static void handleException(String msg, Exception e) { log.error(msg, e); throw new RabbitAdapterMQException(msg, e); } }