• RocketMQ安装和使用

    下载安装

    下载地址:https://www.apache.org/dyn/closer.cgi?path=rocketmq/4.9.4/rocketmq-all-4.9.4-bin-release.zip
    安装:

    unzip rocketmq-all-4.9.4-bin-release.zip
    cd rocketmq-all-4.9.4-bin-release/

    启动Name Server

    nohup sh bin/mqnamesrv &
    tail -f ~/logs/rocketmqlogs/namesrv.log

    在这里插入图片描述
    修改broker配置(默认8g内存太大了)
    vim ./bin/runbroker.sh
    在这里插入图片描述

    启动Broker

    nohup sh bin/mqbroker -n localhost:9876 &
    tail -f ~/logs/rocketmqlogs/broker.log

    在这里插入图片描述
    创建stock主题
    ./bin/mqadmin updateTopic -n localhost:9876 -t stock -c DefaultCluster
    在这里插入图片描述
    application.properties配置

    mq.nameserver.addr=192.168.174.128:9876
mq.topicname=stock

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    生产者发送消息:

    
import com.alibaba.fastjson.JSON;
import com.imooc.miaoshaproject.dao.StockLogDOMapper;
import com.imooc.miaoshaproject.dataobject.StockLogDO;
import com.imooc.miaoshaproject.service.OrderService;
import org.apache.rocketmq.client.exception.MQClientException;
import org.apache.rocketmq.client.producer.*;
import org.apache.rocketmq.common.message.Message;
import org.apache.rocketmq.common.message.MessageExt;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;
import java.nio.charset.Charset;
import java.util.HashMap;
import java.util.Map;

/**
 * Created by hzllb on 2019/2/23.
 */
@Component
public class MqProducer {

    private DefaultMQProducer producer; // 默认生产者

    private TransactionMQProducer transactionMQProducer; // 事务型生产者

    @Value("${mq.nameserver.addr}")
    private String nameAddr;

    @Value("${mq.topicname}")
    private String topicName;


    @Autowired
    private OrderService orderService;

    @Autowired
    private StockLogDOMapper stockLogDOMapper;

    @PostConstruct
    public void init() throws MQClientException {
        //做mq producer的初始化
        producer = new DefaultMQProducer("producer_group");
        producer.setNamesrvAddr(nameAddr);
        producer.start();

        transactionMQProducer = new TransactionMQProducer("transaction_producer_group");
        transactionMQProducer.setNamesrvAddr(nameAddr);
        transactionMQProducer.start();

        transactionMQProducer.setTransactionListener(new TransactionListener() {
            //  第2步执行
            @Override
            public LocalTransactionState executeLocalTransaction(Message msg, Object arg) {
                //真正要做的事  创建订单
                Integer itemId = (Integer) ((Map)arg).get("itemId");
                Integer promoId = (Integer) ((Map)arg).get("promoId");
                Integer userId = (Integer) ((Map)arg).get("userId");
                Integer amount = (Integer) ((Map)arg).get("amount");
                String stockLogId = (String) ((Map)arg).get("stockLogId");
                try {
                    orderService.createOrder(userId,itemId,promoId,amount,stockLogId);
                } catch (Exception e) {
                    e.printStackTrace();
                    //设置对应的stockLog为回滚状态
                    StockLogDO stockLogDO = stockLogDOMapper.selectByPrimaryKey(stockLogId);
                    stockLogDO.setStatus(3);
                    stockLogDOMapper.updateByPrimaryKeySelective(stockLogDO);
                    return LocalTransactionState.ROLLBACK_MESSAGE;
                }
                return LocalTransactionState.COMMIT_MESSAGE;
            }

            //  第2步执行出错后,执行
            @Override
            public LocalTransactionState checkLocalTransaction(MessageExt msg) {
                //根据是否扣减库存成功，来判断要返回COMMIT,ROLLBACK还是继续UNKNOWN
                String jsonString  = new String(msg.getBody());
                Map<String,Object>map = JSON.parseObject(jsonString, Map.class);
                Integer itemId = (Integer) map.get("itemId");
                Integer amount = (Integer) map.get("amount");
                String stockLogId = (String) map.get("stockLogId");
                StockLogDO stockLogDO = stockLogDOMapper.selectByPrimaryKey(stockLogId);
                if(stockLogDO == null){
                    return LocalTransactionState.UNKNOW;
                }
                if(stockLogDO.getStatus().intValue() == 2){
                    return LocalTransactionState.COMMIT_MESSAGE;
                }else if(stockLogDO.getStatus().intValue() == 1){
                    return LocalTransactionState.UNKNOW;
                }
                return LocalTransactionState.ROLLBACK_MESSAGE;
            }
        });
    }

    //事务型同步库存扣减消息 第1步执行
    public boolean transactionAsyncReduceStock(Integer userId,Integer itemId,Integer promoId,Integer amount,String stockLogId){
        Map<String,Object> bodyMap = new HashMap<>();
        bodyMap.put("itemId",itemId);
        bodyMap.put("amount",amount);
        bodyMap.put("stockLogId",stockLogId);

        Map<String,Object> argsMap = new HashMap<>();
        argsMap.put("itemId",itemId);
        argsMap.put("amount",amount);
        argsMap.put("userId",userId);
        argsMap.put("promoId",promoId);
        argsMap.put("stockLogId",stockLogId);

        Message message = new Message(topicName,"increase",
                JSON.toJSON(bodyMap).toString().getBytes(Charset.forName("UTF-8")));
        TransactionSendResult sendResult = null;
        try {

            sendResult = transactionMQProducer.sendMessageInTransaction(message,argsMap);
        } catch (MQClientException e) {
            e.printStackTrace();
            return false;
        }
        if(sendResult.getLocalTransactionState() == LocalTransactionState.ROLLBACK_MESSAGE){
            return false;
        }else if(sendResult.getLocalTransactionState() == LocalTransactionState.COMMIT_MESSAGE){
            return true;
        }else{
            return false;
        }

    }

}


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    消费者

    import com.alibaba.fastjson.JSON;
import com.imooc.miaoshaproject.dao.ItemStockDOMapper;
import org.apache.rocketmq.client.consumer.DefaultMQPushConsumer;
import org.apache.rocketmq.client.consumer.listener.ConsumeConcurrentlyContext;
import org.apache.rocketmq.client.consumer.listener.ConsumeConcurrentlyStatus;
import org.apache.rocketmq.client.consumer.listener.MessageListenerConcurrently;
import org.apache.rocketmq.client.exception.MQClientException;
import org.apache.rocketmq.common.message.Message;
import org.apache.rocketmq.common.message.MessageExt;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;
import java.util.List;
import java.util.Map;

/**
 * Created by hzllb on 2019/2/23.
 */
@Component
public class MqConsumer {

    private DefaultMQPushConsumer consumer;
    @Value("${mq.nameserver.addr}")
    private String nameAddr;

    @Value("${mq.topicname}")
    private String topicName;

    @Autowired
    private ItemStockDOMapper itemStockDOMapper;

    @PostConstruct
    public void init() throws MQClientException {
        consumer = new DefaultMQPushConsumer("stock_consumer_group");
        consumer.setNamesrvAddr(nameAddr);
        consumer.subscribe(topicName,"*");

        consumer.registerMessageListener(new MessageListenerConcurrently() {
            @Override
            public ConsumeConcurrentlyStatus consumeMessage(List<MessageExt> msgs, ConsumeConcurrentlyContext context) {
                //实现库存真正到数据库内扣减的逻辑
                Message msg = msgs.get(0);
                String jsonString  = new String(msg.getBody());
                Map<String,Object>map = JSON.parseObject(jsonString, Map.class);
                Integer itemId = (Integer) map.get("itemId");
                Integer amount = (Integer) map.get("amount");

                itemStockDOMapper.decreaseStock(itemId,amount);
                return ConsumeConcurrentlyStatus.CONSUME_SUCCESS;
            }
        });

        consumer.start();

    }
}

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  • 原文地址：https://blog.csdn.net/ZHUSHANGLIN/article/details/126120874