Spring多事务管理器报错处理

报错如下

Description:

Field defaultUidGenerator in len.hgy.wsearch.interfaces.search.api.CityController required a single bean, but 2 were found:
	- transactionManager: defined by method 'transactionManager' in class path resource [org/springframework/boot/autoconfigure/jdbc/DataSourceTransactionManagerAutoConfiguration$JdbcTransactionManagerConfiguration.class]
	- connectionFactoryTransactionManager: defined by method 'connectionFactoryTransactionManager' in class path resource [org/springframework/boot/autoconfigure/r2dbc/R2dbcTransactionManagerAutoConfiguration.class]

This may be due to missing parameter name information
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意思是出现两个事务管理器

TransactionAspectSupport#determineTransactionManager

org.springframework.transaction.interceptor.TransactionAspectSupport#determineTransactionManager
这个是获取事务管理器的类, 在需要事务时候从这里获取(事务会包含数据源, 有缓存,提高性能)

	protected TransactionManager determineTransactionManager(@Nullable TransactionAttribute txAttr) {
		// Do not attempt to lookup tx manager if no tx attributes are set
		if (txAttr == null || this.beanFactory == null) {
			return getTransactionManager();
		}
		// 这个qualifier 其实就是@Transactional注解的value或者transactionManager的值, 作为bean名称
		String qualifier = txAttr.getQualifier();
		if (StringUtils.hasText(qualifier)) {
			return determineQualifiedTransactionManager(this.beanFactory, qualifier);
		} // 如果指定了管理器的bean名称, 就使用bean名称获取
		else if (StringUtils.hasText(this.transactionManagerBeanName)) {
			return determineQualifiedTransactionManager(this.beanFactory, this.transactionManagerBeanName);
		}
		else {
			TransactionManager defaultTransactionManager = getTransactionManager();
			if (defaultTransactionManager == null) {
				defaultTransactionManager = this.transactionManagerCache.get(DEFAULT_TRANSACTION_MANAGER_KEY);
				if (defaultTransactionManager == null) {
					defaultTransactionManager = 
					// 默认是更具TransactionManagerc的class类型获取
					this.beanFactory.getBean(TransactionManager.class);
					this.transactionManagerCache.putIfAbsent(
							DEFAULT_TRANSACTION_MANAGER_KEY, defaultTransactionManager);
				}
			}
			return defaultTransactionManager;
		}
	}
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由于我项目使用mybatis又使用了响应式变成的以来, 所以项目又两个事务管理器, 导致代码获取唯一bean报错

如何解决

首先我们要在defaultTransactionManager = this.beanFactory.getBean(TransactionManager.class);这行代码大断电, 然后使用idea计算
((DefaultListableBeanFactory)this.beanFactory).getBeansOfType(TransactionManager.class)
计算结果是:

"transactionManager" -> {JdbcTransactionManager@8195} 
"connectionFactoryTransactionManager" -> {R2dbcTransactionManager@8197} 
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所以我们知道了我们事务管理器的beanName是transactionManager

然后我们可以在@Transactional加上value值’transactionManager’, 问题解决