ActiveMQ的使用笔记（基本实现原理）

具体原理不进行深入，会用就好。

第一：当然是先安装ActiveMQ，选择操作系统位数，安装成功以后，输入网址http://ip:8161/admin/，会出现相关页面，账号密码都是admin。在这个页面上可以看到消息队列的信息。consume和send使用较多。

第二：创建produce和consume。

　　基本的原理都是一样的，JMS(java message send)的13个规范之一，消息中间件的一些组件拼接连通就行了。具体参考代码注释。

容易出错的地方是消息的格式。

这里有点对点模式和发布/订阅模式。我使用的时候是在初始化ContextListener的时候初始化ActiveMQ，然后并重载了onMessage事件（MessageConsumer里面定义了一些接口，可以去使用），这样就不需要一直主动去询问提供者了，队列中有消息时会自动触发该事件。

参考代码：

package com.enjoyor.soa.traffic.server.nmim.listener;

import javax.jms.Message;
import javax.jms.MessageListener;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

import com.enjoyor.soa.traffic.server.nmim.util.ActiveMQUtil;
import com.enjoyor.soa.traffic.server.nmim.util.Constants;
import com.enjoyor.soa.traffic.server.nmim.util.InitConfig;
import com.enjoyor.soa.traffic.server.nmim.service.inner.MqManageService;
import com.enjoyor.soa.traffic.util.frame.spring.SpringContextUtil;
import com.enjoyor.soa.traffic.util.helper.LoggerHelper;
import com.enjoyor.soa.traffic.util.pojo.ResultPojo;

/**
 *
 * ContextListener
 * 2016-11-25
 *
 */
public class ContextListener implements ServletContextListener
{
    public void contextDestroyed(ServletContextEvent arg0)
    {
        System.out.print("contextDestroyed");
    }

    MqManageService manageService;

    public void contextInitialized(ServletContextEvent arg0)
    {
        System.out.print("contextInitialized");
        String MQNAME = "";
        InitConfig initConfig = new InitConfig();
        initConfig.init();
        MQNAME = InitConfig.confCache.get(Constants.MQNAME).toString();
        ActiveMQUtil.getInstance().receive("queue://" + MQNAME, new MessageListener() {
            @Override
            public void onMessage(Message msg) {
                try {
                    if(null==manageService){
                        manageService = (MqManageService) SpringContextUtil.getBean("mqManageService");
                        manageService.setListDic();
                    }
                    //MqManageService manageService = (MqManageService) SpringContextUtil.getBean("mqManageService");
                    ResultPojo pojo = manageService.getMqMsg(msg);
                    if(!pojo.getappCode().equals("0")){
                        LoggerHelper.LOG.error("接收失败"+pojo.getResultList());
                    }
                } catch (Exception e) {
                    LoggerHelper.LOG.error(e);
                }

            }
        });
    }

}

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
package com.enjoyor.soa.traffic.server.nmim.util;

import javax.jms.Connection;
import javax.jms.ConnectionFactory;
import javax.jms.Destination;
import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.MessageConsumer;
import javax.jms.MessageListener;
import javax.jms.Session;
import javax.jms.TextMessage;

import org.apache.activemq.command.ActiveMQQueue;
import org.apache.activemq.command.ActiveMQTopic;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.jms.core.JmsTemplate;
import org.springframework.jms.core.MessageCreator;

public class ActiveMQUtil {

    private ActiveMQUtil(){

    }
    private JmsTemplate jmsTemplate;
    public JmsTemplate getJmsTemplate() {
        return jmsTemplate;
    }
    public void setJmsTemplate(JmsTemplate jmsTemplate) {
        this.jmsTemplate = jmsTemplate;
    }

    private static ActiveMQUtil mq;
    public static ActiveMQUtil getInstance(){
        if(mq==null){
            ApplicationContext context = new ClassPathXmlApplicationContext("activemq.xml");
            mq=(ActiveMQUtil)context.getBean("activeMQUtil");
        }
        return mq;
    }

    public Destination getDestination(String name){
        Destination dest=null;
        boolean pubSubDomain=name.toLowerCase().indexOf("topic://")==0;
        String destName = name.replaceFirst("(?i)(topic|queue)://", "");
        if(pubSubDomain){
            dest= new ActiveMQTopic(destName);
        }else{
            dest= new ActiveMQQueue(destName);
        }
        return dest;
    }

    public String receive(Destination dest) {
        try {
            TextMessage txtmsg = (TextMessage) getInstance().getJmsTemplate().receive(dest);
            if(null!=txtmsg)return txtmsg.getText();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }
    public String receive(String name) {
        return receive(getDestination(name));
    }
    public Connection receive(Destination dest,MessageListener listener){
        try{
            ConnectionFactory factory = getInstance().getJmsTemplate().getConnectionFactory();
            Connection connection = factory.createConnection();
            connection.start();

            final Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
            MessageConsumer consumer = session.createConsumer(dest);
            consumer.setMessageListener(listener);
            return connection;
        } catch (JMSException e) { }
        return null;
    }
    public Connection receive(String name,MessageListener listener){
        return receive(getDestination(name),listener);
    }

    public void send(Destination dest,final String msg){
        try {
            jmsTemplate.send(dest,new MessageCreator() {
                public Message createMessage(Session session) throws JMSException {
                    TextMessage message = session.createTextMessage(msg);
                    return message;
                }
            });
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    public void send(String name,final String msg){
        send(getDestination(name),msg);
    }

}

注意将ContextListener初始化时注入spring容器中。任何类都需要一个入口，只有进入spring容器中，在jvm中被调用，才有存在的价值。