基于消息队列实现分布式事务,实现消息最终一致性
一、如何基于消息队列实现分布式事务?
通过消息队列实现分布式事务的话,可以保证当前数据的最终一致性。实现思路:将大的分布式事务,进行拆分,拆分成若干个小的本地事务,只要每一个小的本地事务是执行成功的,那就代表当前的分布式事务是执行成功的。下面以用户下单增加积分,来进行消息队列实现分布式事务的操作。
功能实现流程图如下:
主要包含三个角色:订单服务,消息队列和用户服务。
步骤(1-4):订单服务
1.首先,在订单服务中,会生成订单相关数据,并添加到数据库中。
2.接着会在订单数据库中,创建任务表 ,会向任务表添加数据,(Username,orderID,point积分)
3.设置定时任务,扫描任务表,获取相关数据,如每隔7S扫描一次
4.发送任务数据到MQ
步骤(5-12):用户服务
5.6.7.用户服务会接收消息,保证消息的不可重复消费,判断在Redis和 在数据库中是否存在。防止重复处理,不要重复添加积分。
用户服务正在执行消息
如果不存在,继续业务功能。
添加本地事务
12.通知订单服务
步骤(13):订单服务
13.删除任务表数据。
二、 准备工作
2.1 shangcheng_order库新增数据表
任务表:
DROP TABLE IF EXISTS `tb_task`; CREATE TABLE `tb_task` ( `id` bigint(32) NOT NULL AUTO_INCREMENT COMMENT '任务id', `create_time` datetime DEFAULT NULL, `update_time` datetime DEFAULT NULL, `delete_time` datetime DEFAULT NULL, `task_type` varchar(32) DEFAULT NULL COMMENT '任务类型', `mq_exchange` varchar(64) DEFAULT NULL COMMENT '交换机名称', `mq_routingkey` varchar(64) DEFAULT NULL COMMENT 'routingkey', `request_body` varchar(512) DEFAULT NULL COMMENT '任务请求的内容', `status` varchar(32) DEFAULT NULL COMMENT '任务状态', `errormsg` varchar(512) DEFAULT NULL COMMENT '任务错误信息', PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
历史任务表:
DROP TABLE IF EXISTS `tb_task_his`; CREATE TABLE `tb_task_his` ( `id` bigint(32) NOT NULL AUTO_INCREMENT COMMENT '任务id', `create_time` datetime DEFAULT NULL, `update_time` datetime DEFAULT NULL, `delete_time` datetime DEFAULT NULL, `task_type` varchar(32) DEFAULT NULL COMMENT '任务类型', `mq_exchange` varchar(64) DEFAULT NULL COMMENT '交换机名称', `mq_routingkey` varchar(64) DEFAULT NULL COMMENT 'routingkey', `request_body` varchar(512) DEFAULT NULL COMMENT '任务请求的内容', `status` varchar(32) DEFAULT NULL COMMENT '任务状态', `errormsg` varchar(512) DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=9 DEFAULT CHARSET=utf8;
2.2 shangcheng_service_order_api添加相关实体类
@Table(name="tb_task") public class Task { @Id private Long id; @Column(name = "create_time") private Date createTime; @Column(name = "update_time") private Date updateTime; @Column(name = "delete_time") private Date deleteTime; @Column(name = "task_type") private String taskType; @Column(name = "mq_exchange") private String mqExchange; @Column(name = "mq_routingkey") private String mqRoutingkey; @Column(name = "request_body") private String requestBody; @Column(name = "status") private String status; @Column(name = "errormsg") private String errormsg; //getter,setter略 }
@Table(name="tb_task_his") public class TaskHis { @Id private Long id; @Column(name = "create_time") private Date createTime; @Column(name = "update_time") private Date updateTime; @Column(name = "delete_time") private Date deleteTime; @Column(name = "task_type") private String taskType; @Column(name = "mq_exchange") private String mqExchange; @Column(name = "mq_routingkey") private String mqRoutingkey; @Column(name = "request_body") private String requestBody; @Column(name = "status") private String status; @Column(name = "errormsg") private String errormsg; //getter,setter略 }
2.3 shangcheng_user新增积分日志表
DROP TABLE IF EXISTS `tb_point_log`; CREATE TABLE `tb_point_log` ( `order_id` varchar(200) NOT NULL, `user_id` varchar(200) NOT NULL, `point` int(11) NOT NULL, PRIMARY KEY (`order_id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
2.4 shangcheng_service_user_api添加实体类 PointLog
@Table(name="tb_point_log") public class PointLog { private String orderId; private String userId; private Integer point; //getter,setter略 }
2.5 shangcheng_service_order添加rabbitMQ配置类
@Configuration public class RabbitMQConfig { //添加积分任务交换机 public static final String EX_BUYING_ADDPOINTUSER = "ex_buying_addpointuser"; //添加积分消息队列 public static final String CG_BUYING_ADDPOINT = "cg_buying_addpoint"; //完成添加积分消息队列 public static final String CG_BUYING_FINISHADDPOINT = "cg_buying_finishaddpoint"; //添加积分路由key public static final String CG_BUYING_ADDPOINT_KEY = "addpoint"; //完成添加积分路由key public static final String CG_BUYING_FINISHADDPOINT_KEY = "finishaddpoint"; /** * 交换机配置 * @return the exchange */ @Bean(EX_BUYING_ADDPOINTUSER) public Exchange EX_BUYING_ADDPOINTUSER() { return ExchangeBuilder.directExchange(EX_BUYING_ADDPOINTUSER).durable(true).build(); } //声明队列 @Bean(CG_BUYING_FINISHADDPOINT) public Queue QUEUE_CG_BUYING_FINISHADDPOINT() { Queue queue = new Queue(CG_BUYING_FINISHADDPOINT); return queue; } //声明队列 @Bean(CG_BUYING_ADDPOINT) public Queue QUEUE_CG_BUYING_ADDPOINT() { Queue queue = new Queue(CG_BUYING_ADDPOINT); return queue; } /** * 绑定队列到交换机 . * @param queue the queue * @param exchange the exchange * @return the binding */ @Bean public Binding BINDING_QUEUE_FINISHADDPOINT(@Qualifier(CG_BUYING_FINISHADDPOINT) Queue queue, @Qualifier(EX_BUYING_ADDPOINTUSER) Exchange exchange) { return BindingBuilder.bind(queue).to(exchange).with(CG_BUYING_FINISHADDPOINT_KEY).noargs(); } @Bean public Binding BINDING_QUEUE_ADDPOINT(@Qualifier(CG_BUYING_ADDPOINT) Queue queue, @Qualifier(EX_BUYING_ADDPOINTUSER) Exchange exchange) { return BindingBuilder.bind(queue).to(exchange).with(CG_BUYING_ADDPOINT_KEY).noargs(); } }
三、 订单服务添加任务并发送
步骤1: 修改添加订单方法
当添加订单的时候,添加任务表中相关数据, 代码如下:
//增加任务表记录 Task task = new Task(); task.setCreateTime(new Date()); task.setUpdateTime(new Date()); task.setMqExchange(RabbitMQConfig.EX_BUYING_ADDPOINTURSE); task.setMqRoutingkey(RabbitMQConfig.CG_BUYING_ADDPOINT_KEY); Map map = new HashMap(); map.put("userName",order.getUsername()); map.put("orderId",order.getId()); map.put("point",order.getPayMoney()); task.setRequestBody(JSON.toJSONString(map)); taskMapper.insertSelective(task);
步骤2: 定时扫描任务表最新数据
订单服务新增定时任务类,获取小于系统当前时间的所有任务数据
(1) 修改订单服务启动类,添加开启定时任务注解
@EnableScheduling
(2) 定义定时任务类
查询最新数据
更新taskMapper新增方法,查询所有小于系统当前时间的数据
public interface TaskMapper extends Mapper<Task> { @Select("SELECT * from tb_task WHERE update_time<#{currentTime}") @Results({@Result(column = "create_time",property = "createTime"), @Result(column = "update_time",property = "updateTime"), @Result(column = "delete_time",property = "deleteTime"), @Result(column = "task_type",property = "taskType"), @Result(column = "mq_exchange",property = "mqExchange"), @Result(column = "mq_routingkey",property = "mqRoutingkey"), @Result(column = "request_body",property = "requestBody"), @Result(column = "status",property = "status"), @Result(column = "errormsg",property = "errormsg")}) List<Task> findTaskLessTanCurrentTime(Date currentTime); }
任务类实现:
@Component public class QueryPointTask { @Autowired private RabbitTemplate rabbitTemplate; @Autowired private TaskMapper taskMapper; @Scheduled(cron = "0 0/2 * * * ?") public void queryTask(){ //1.获取小于系统当前时间数据 List<Task> taskList = taskMapper.findTaskLessTanCurrentTime(new Date()); if (taskList!=null && taskList.size()>0){ //将任务数据发送到消息队列 for (Task task : taskList) { rabbitTemplate.convertAndSend(RabbitMQConfig.EX_BUYING_ADDPOINTURSE,RabbitMQConfig.CG_BUYING_ADDPOINT_KEY, JSON.toJSONString(task)); } } } }
五、 用户服务更改积分
步骤1: 添加rabbitmq配置类(与订单服务相同)
@Configuration public class RabbitMQConfig { //添加积分任务交换机 public static final String EX_BUYING_ADDPOINTURSE = "ex_buying_addpointurse"; //添加积分消息队列 public static final String CG_BUYING_ADDPOINT = "cg_buying_addpoint"; //完成添加积分消息队列 public static final String CG_BUYING_FINISHADDPOINT = "cg_buying_finishaddpoint"; //添加积分路由key public static final String CG_BUYING_ADDPOINT_KEY = "addpoint"; //完成添加积分路由key public static final String CG_BUYING_FINISHADDPOINT_KEY = "finishaddpoint"; /** * 交换机配置 * @return the exchange */ @Bean(EX_BUYING_ADDPOINTURSE) public Exchange EX_DECLARE() { return ExchangeBuilder.directExchange(EX_BUYING_ADDPOINTURSE).durable(true).build(); } //声明队列 @Bean(CG_BUYING_FINISHADDPOINT) public Queue QUEUE_CG_BUYING_FINISHADDPOINT() { Queue queue = new Queue(CG_BUYING_FINISHADDPOINT); return queue; } //声明队列 @Bean(CG_BUYING_ADDPOINT) public Queue QUEUE_CG_BUYING_ADDPOINT() { Queue queue = new Queue(CG_BUYING_ADDPOINT); return queue; } /** * 绑定队列到交换机 . * @param queue the queue * @param exchange the exchange * @return the binding */ @Bean public Binding BINDING_QUEUE_FINISHADDPOINT(@Qualifier(CG_BUYING_FINISHADDPOINT) Queue queue, @Qualifier(EX_BUYING_ADDPOINTURSE) Exchange exchange) { return BindingBuilder.bind(queue).to(exchange).with(CG_BUYING_FINISHADDPOINT_KEY).noargs(); } @Bean public Binding BINDING_QUEUE_ADDPOINT(@Qualifier(CG_BUYING_ADDPOINT) Queue queue, @Qualifier(EX_BUYING_ADDPOINTURSE) Exchange exchange) { return BindingBuilder.bind(queue).to(exchange).with(CG_BUYING_ADDPOINT_KEY).noargs(); } }
步骤2: 定义消息监听类:
@Component public class AddPointListener { @Autowired private UserService userService; @Autowired private RedisTemplate redisTemplate; @Autowired private RabbitTemplate rabbitTemplate; @RabbitListener(queues = RabbitMQConfig.CG_BUYING_ADDPOINT) public void receiveMessage(String message){ Task task = JSON.parseObject(message, Task.class); if (task == null || StringUtils.isEmpty(task.getRequestBody())){ return; } //判断redis中是否存在内容 Object value = redisTemplate.boundValueOps(task.getId()).get(); if (value != null){ return; } //更新用户积分 int result = userService.updateUserPoints(task); if (result<=0){ return; } //返回通知 rabbitTemplate.convertAndSend(RabbitMQConfig.EX_BUYING_ADDPOINTURSE,RabbitMQConfig.CG_BUYING_FINISHADDPOINT_KEY,JSON.toJSONString(task)); } }
步骤3: 定义修改用户积分实现
实现思路:
1)判断当前订单是否操作过
2)将任务存入redis
3)修改用户积分
4)添加积分日志表记录
5)删除redis中记录
@Autowired private PointLogMapper pointLogMapper; /** * 修改用户积分 * @param task * @return */ @Override @Transactional public int updateUserPoints(Task task) { Map info = JSON.parseObject(task.getRequestBody(), Map.class); String userName = info.get("userName").toString(); String orderId = info.get("orderId").toString(); int point = (int) info.get("point"); //判断当前订单是否操作过 PointLog pointLog = pointLogMapper.findLogInfoByOrderId(orderId); if (pointLog != null){ return 0; } //将任务存入redis redisTemplate.boundValueOps(task.getId()).set("exist",1,TimeUnit.MINUTES); //修改用户积分 int result = userMapper.updateUserPoint(userName, point); if (result<=0){ return result; } //添加积分日志表记录 pointLog = new PointLog(); pointLog.setOrderId(orderId); pointLog.setPoint(point); pointLog.setUserId(userName); result = pointLogMapper.insertSelective(pointLog); if (result<=0){ return result; } //删除redis中的记录 redisTemplate.delete(task.getId()); return 1; }
步骤4: 定义根据订单id查询积分日志表
定义PointLogMapper,实现根据订单id查询:
public interface PointLogMapper extends Mapper<PointLog> { @Select("select * from tb_point_log where order_id=#{orderId}") PointLog findLogInfoByOrderId(@Param("orderId") String orderId); }
五、 订单服务删除原任务
步骤1: 定义监听类
在订单服务中定义监听类,用于监听队列,如果队列中有消息,则删除原任务防止消息重复发送,并对任务信息进行记录
@Component public class DelTaskListener { @Autowired private TaskService taskService; @RabbitListener(queues = RabbitMQConfig.CG_BUYING_FINISHADDPOINT) public void receiveMessage(String message){ Task task = JSON.parseObject(message, Task.class); taskService.delTask(task); } }
步骤2: 定义任务service
public interface TaskService { void delTask(Task task); }
@Service @Transactional public class TaskServiceImpl implements TaskService { @Autowired private TaskMapper taskMapper; @Autowired private TaskHisMapper taskHisMapper; @Override public void delTask(Task task) { //1. 设置删除时间 task.setDeleteTime(new Date()); Long id = task.getId(); task.setId(null); //bean复制 TaskHis taskHis = new TaskHis(); BeanUtils.copyProperties(task,taskHis); //记录任务信息 taskHisMapper.insertSelective(taskHis); //删除原任务 task.setId(id); taskMapper.deleteByPrimaryKey(task); } }
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