Spring 七种事务传播行为

1. Transactional 注解

package org.springframework.transaction.annotation;

public @interface Transactional {
	/**
	 * 设置事务传播行为
	 * 默认是 Propagation#REQUIRED
	 */
	Propagation propagation() default Propagation.REQUIRED;
}

2. 七种事务传播行为

事务传播行为就是 method 1 调用 method 2 存在几个事务，在哪个事务中执行

注意： 底下表格说的是 同一线程 ，后面讨论多线程。

序号	隔离级别	行为表现
1	REQUIRED (默认值)	如果当前当前方法事务存在被调用方法就在同一个事务中进行，否则启动一个新的事务
2	SUPPORTS	表明方法支持事务，存在事务就在事务中执行
3	MANDATORY	表明方法必须在事务中运行，如果事务不存在抛异常
4	REQUIRES_NEW	表明当前方法必须运行在自己的事务中，会启动一个新的事务，上一个事务被挂起
5	NOT_SUPPORTED	表明方法不应该运行在事务中，如果存在事务，则事务被挂起
6	NEVER	表明方法不应该运行在事务中，如果在事务中则抛异常
7	NESTED	嵌套事务，可以独立于当前事务单独提交或回滚

3. 多线程

如果这些相互嵌套调用的方法工作在不同的线程中，则不同线程下的事务方法工作在独立的事务中

4. 附录

• Spring 官方文档对事务传播行为的说明
• Propagation 源代码

/*
 * Copyright 2002-2019 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.transaction.annotation;

import org.springframework.transaction.TransactionDefinition;

/**
 * Enumeration that represents transaction propagation behaviors for use
 * with the {@link Transactional} annotation, corresponding to the
 * {@link TransactionDefinition} interface.
 *
 * @author Colin Sampaleanu
 * @author Juergen Hoeller
 * @since 1.2
 */
public enum Propagation {

	/**
	 * Support a current transaction, create a new one if none exists.
	 * Analogous to EJB transaction attribute of the same name.
	 * <p>This is the default setting of a transaction annotation.
	 */
	REQUIRED(TransactionDefinition.PROPAGATION_REQUIRED),

	/**
	 * Support a current transaction, execute non-transactionally if none exists.
	 * Analogous to EJB transaction attribute of the same name.
	 * <p>Note: For transaction managers with transaction synchronization,
	 * {@code SUPPORTS} is slightly different from no transaction at all,
	 * as it defines a transaction scope that synchronization will apply for.
	 * As a consequence, the same resources (JDBC Connection, Hibernate Session, etc)
	 * will be shared for the entire specified scope. Note that this depends on
	 * the actual synchronization configuration of the transaction manager.
	 * @see org.springframework.transaction.support.AbstractPlatformTransactionManager#setTransactionSynchronization
	 */
	SUPPORTS(TransactionDefinition.PROPAGATION_SUPPORTS),

	/**
	 * Support a current transaction, throw an exception if none exists.
	 * Analogous to EJB transaction attribute of the same name.
	 */
	MANDATORY(TransactionDefinition.PROPAGATION_MANDATORY),

	/**
	 * Create a new transaction, and suspend the current transaction if one exists.
	 * Analogous to the EJB transaction attribute of the same name.
	 * <p><b>NOTE:</b> Actual transaction suspension will not work out-of-the-box
	 * on all transaction managers. This in particular applies to
	 * {@link org.springframework.transaction.jta.JtaTransactionManager},
	 * which requires the {@code javax.transaction.TransactionManager} to be
	 * made available to it (which is server-specific in standard Java EE).
	 * @see org.springframework.transaction.jta.JtaTransactionManager#setTransactionManager
	 */
	REQUIRES_NEW(TransactionDefinition.PROPAGATION_REQUIRES_NEW),

	/**
	 * Execute non-transactionally, suspend the current transaction if one exists.
	 * Analogous to EJB transaction attribute of the same name.
	 * <p><b>NOTE:</b> Actual transaction suspension will not work out-of-the-box
	 * on all transaction managers. This in particular applies to
	 * {@link org.springframework.transaction.jta.JtaTransactionManager},
	 * which requires the {@code javax.transaction.TransactionManager} to be
	 * made available to it (which is server-specific in standard Java EE).
	 * @see org.springframework.transaction.jta.JtaTransactionManager#setTransactionManager
	 */
	NOT_SUPPORTED(TransactionDefinition.PROPAGATION_NOT_SUPPORTED),

	/**
	 * Execute non-transactionally, throw an exception if a transaction exists.
	 * Analogous to EJB transaction attribute of the same name.
	 */
	NEVER(TransactionDefinition.PROPAGATION_NEVER),

	/**
	 * Execute within a nested transaction if a current transaction exists,
	 * behave like {@code REQUIRED} otherwise. There is no analogous feature in EJB.
	 * <p>Note: Actual creation of a nested transaction will only work on specific
	 * transaction managers. Out of the box, this only applies to the JDBC
	 * DataSourceTransactionManager. Some JTA providers might support nested
	 * transactions as well.
	 * @see org.springframework.jdbc.datasource.DataSourceTransactionManager
	 */
	NESTED(TransactionDefinition.PROPAGATION_NESTED);


	private final int value;


	Propagation(int value) {
		this.value = value;
	}

	public int value() {
		return this.value;
	}

}