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如何设计幂等性接口防止Seata事务悬挂？

news 来源：原创 2025/6/15 8:27:40

Seata事务悬挂主要发生在分布式事务的二阶段处理过程中，当分支事务提交/回滚状态与全局事务状态不一致时产生。以下是完整的防悬挂幂等接口设计方案及实现代码：

一、悬挂产生原理

二、幂等接口核心实现

public class IdempotentService {@Autowiredprivate IdempotentRecordMapper recordMapper;/*** 防悬挂校验（前置拦截）* @param xid 全局事务ID* @param branchId 分支事务ID*/public void checkHanging(String xid, long branchId) {// 1. 检查全局事务状态GlobalTransaction tx = GlobalTransactionContext.getCurrentOrCreate();if (tx.getStatus() == GlobalStatus.TimeoutRollbacking) {throw new TransactionHangingException("事务已超时回滚");}// 2. 防悬挂核心校验（数据库记录检查）IdempotentRecord record = recordMapper.selectByXidAndBranch(xid, branchId);if (record != null) {switch (record.getStatus()) {case 1: throw new DuplicateCommitException("重复提交");case 2: throw new AlreadyRollbackException("事务已回滚");}}}/*** 记录事务状态（后置处理）*/@Transactionalpublic void recordStatus(String xid, long branchId, int status) {IdempotentRecord record = new IdempotentRecord();record.setXid(xid);record.setBranchId(branchId);record.setStatus(status);recordMapper.insertOnDuplicateUpdate(record);}
}

三、防悬挂事务表设计

CREATE TABLE idempotent_record (id BIGINT AUTO_INCREMENT PRIMARY KEY,xid VARCHAR(128) NOT NULL COMMENT '全局事务ID',branch_id BIGINT NOT NULL COMMENT '分支事务ID',status TINYINT NOT NULL COMMENT '0-进行中 1-已提交 2-已回滚',create_time TIMESTAMP DEFAULT CURRENT_TIMESTAMP,update_time TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,UNIQUE INDEX udx_xid_branch (xid, branch_id)
) COMMENT='防悬挂事务记录表';

四、Seata集成配置

@Configuration
public class SeataInterceptorConfig implements WebMvcConfigurer {@Autowiredprivate IdempotentService idempotentService;@Overridepublic void addInterceptors(InterceptorRegistry registry) {registry.addInterceptor(new HandlerInterceptor() {@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) {String xid = RootContext.getXID();if (xid != null) {// 获取分支事务IDlong branchId = BranchRegisterContext.getBranchId();// 执行防悬挂校验idempotentService.checkHanging(xid, branchId);}return true;}@Overridepublic void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) {String xid = RootContext.getXID();if (xid != null) {long branchId = BranchRegisterContext.getBranchId();// 记录事务最终状态int status = ex == null ? 1 : 2;idempotentService.recordStatus(xid, branchId, status);}}});}
}

五、异常处理机制

@RestControllerAdvice
public class GlobalExceptionHandler {@ExceptionHandler(TransactionHangingException.class)public Response handleHangingException(TransactionHangingException e) {// 触发事务补偿SeataCompensator.compensate(e.getXid());return Response.fail(504, "事务已触发补偿机制");}@ExceptionHandler(DuplicateCommitException.class)public Response handleDuplicateCommit(DuplicateCommitException e) {// 返回幂等成功响应return Response.success("操作已成功处理");}
}