【Spring框架三】Spring常用注解之Transactional

Spring可以通过注解@Transactional来为业务逻辑层的方法(调用DAO完成持久化动作)添加事务能力，如下是@Transactional注解的定义：

 

/*
 * Copyright 2002-2010 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
 *
 *      http://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 java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

import org.springframework.transaction.TransactionDefinition;

/**
 * Describes transaction attributes on a method or class.
 *
 * <p>This annotation type is generally directly comparable to Spring's
 * {@link org.springframework.transaction.interceptor.RuleBasedTransactionAttribute}
 * class, and in fact {@link AnnotationTransactionAttributeSource} will directly
 * convert the data to the latter class, so that Spring's transaction support code
 * does not have to know about annotations. If no rules are relevant to the exception,
 * it will be treated like
 * {@link org.springframework.transaction.interceptor.DefaultTransactionAttribute}
 * (rolling back on runtime exceptions).
 *
 * <p>For specific information about the semantics of this annotation's attributes,
 * consider the {@link org.springframework.transaction.TransactionDefinition} and
 * {@link org.springframework.transaction.interceptor.TransactionAttribute} javadocs.
 *
 * @author Colin Sampaleanu
 * @author Juergen Hoeller
 * @since 1.2
 * @see org.springframework.transaction.interceptor.TransactionAttribute
 * @see org.springframework.transaction.interceptor.DefaultTransactionAttribute
 * @see org.springframework.transaction.interceptor.RuleBasedTransactionAttribute
 */
@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Inherited
@Documented
public @interface Transactional {

	/**
	 * A qualifier value for the specified transaction.
	 * <p>May be used to determine the target transaction manager,
	 * matching the qualifier value (or the bean name) of a specific
	 * {@link org.springframework.transaction.PlatformTransactionManager}
	 * bean definition.
	 */
	String value() default "";

	/**
	 * The transaction propagation type.
	 * Defaults to {@link Propagation#REQUIRED}.
	 * @see org.springframework.transaction.interceptor.TransactionAttribute#getPropagationBehavior()
	 */
	Propagation propagation() default Propagation.REQUIRED;

	/**
	 * The transaction isolation level.
	 * Defaults to {@link Isolation#DEFAULT}.
	 * @see org.springframework.transaction.interceptor.TransactionAttribute#getIsolationLevel()
	 */
	Isolation isolation() default Isolation.DEFAULT;

	/**
	 * The timeout for this transaction.
	 * Defaults to the default timeout of the underlying transaction system.
	 * @see org.springframework.transaction.interceptor.TransactionAttribute#getTimeout()
	 */
	int timeout() default TransactionDefinition.TIMEOUT_DEFAULT;

	/**
	 * <code>true</code> if the transaction is read-only.
	 * Defaults to <code>false</code>.
	 * <p>This just serves as a hint for the actual transaction subsystem;
	 * it will <i>not necessarily</i> cause failure of write access attempts.
	 * A transaction manager which cannot interpret the read-only hint will
	 * <i>not</i> throw an exception when asked for a read-only transaction.
	 * @see org.springframework.transaction.interceptor.TransactionAttribute#isReadOnly()
	 */
	boolean readOnly() default false;

	/**
	 * Defines zero (0) or more exception {@link Class classes}, which must be a
	 * subclass of {@link Throwable}, indicating which exception types must cause
	 * a transaction rollback.
	 * <p>This is the preferred way to construct a rollback rule, matching the
	 * exception class and subclasses.
	 * <p>Similar to {@link org.springframework.transaction.interceptor.RollbackRuleAttribute#RollbackRuleAttribute(Class clazz)}
	 */
	Class<? extends Throwable>[] rollbackFor() default {};

	/**
	 * Defines zero (0) or more exception names (for exceptions which must be a
	 * subclass of {@link Throwable}), indicating which exception types must cause
	 * a transaction rollback.
	 * <p>This can be a substring, with no wildcard support at present.
	 * A value of "ServletException" would match
	 * {@link javax.servlet.ServletException} and subclasses, for example.
	 * <p><b>NB: </b>Consider carefully how specific the pattern is, and whether
	 * to include package information (which isn't mandatory). For example,
	 * "Exception" will match nearly anything, and will probably hide other rules.
	 * "java.lang.Exception" would be correct if "Exception" was meant to define
	 * a rule for all checked exceptions. With more unusual {@link Exception}
	 * names such as "BaseBusinessException" there is no need to use a FQN.
	 * <p>Similar to {@link org.springframework.transaction.interceptor.RollbackRuleAttribute#RollbackRuleAttribute(String exceptionName)}
	 */
	String[] rollbackForClassName() default {};

	/**
	 * Defines zero (0) or more exception {@link Class Classes}, which must be a
	 * subclass of {@link Throwable}, indicating which exception types must <b>not</b>
	 * cause a transaction rollback.
	 * <p>This is the preferred way to construct a rollback rule, matching the
	 * exception class and subclasses.
	 * <p>Similar to {@link org.springframework.transaction.interceptor.NoRollbackRuleAttribute#NoRollbackRuleAttribute(Class clazz)}
	 */
	Class<? extends Throwable>[] noRollbackFor() default {};

	/**
	 * Defines zero (0) or more exception names (for exceptions which must be a
	 * subclass of {@link Throwable}) indicating which exception types must <b>not</b>
	 * cause a transaction rollback.
	 * <p>See the description of {@link #rollbackForClassName()} for more info on how
	 * the specified names are treated.
	 * <p>Similar to {@link org.springframework.transaction.interceptor.NoRollbackRuleAttribute#NoRollbackRuleAttribute(String exceptionName)}
	 */
	String[] noRollbackForClassName() default {};

}

 

@Tranactional注解分析

• 作用域：Transactional作用于类上表示类上所有的方法使用指定的事务管理策略，作用于方法表示该方法使用指定的事务管理策略；如果方法和类同时定义了@Tranactional注解，那么方法上定义的@Tranactional的属性覆盖类上定义的@Tranactional的属性
• value： 用于匹配Spring中定义的tranactionManager的名字，默认是Spring中名称为transactionManager的事务管理器
• propagation：事务传播属性，默认是Propagation.REQUIRED
• isolation：事务隔离级别，默认是Isolation.DEFAULT，它是指数据库的默认隔离级别
• timeout：事务超时时间，默认是TransactionDefinition.TIMEOUT_DEFAULT，它是指数据库的默认的事务超时时间

参 数 名 称	功 能 描 述
readOnly	该属性用于设置当前事务是否为只读事务，设置为true表示只读，false则表示可读写，默认值为false。例如：@Transactional(readOnly=true)
rollbackFor	该属性用于设置需要进行回滚的异常类数组，当方法中抛出指定异常数组中的异常时，则进行事务回滚。例如： 指定单一异常类：@Transactional(rollbackFor=RuntimeException.class) 指定多个异常类：@Transactional(rollbackFor={RuntimeException.class, Exception.class})

rollbackForClassName	该属性用于设置需要进行回滚的异常类名称数组，当方法中抛出指定异常名称数组中的异常时，则进行事务回滚。例如： 指定单一异常类名称：@Transactional(rollbackForClassName="RuntimeException") 指定多个异常类名称：@Transactional(rollbackForClassName={"RuntimeException","Exception"})
noRollbackFor	该属性用于设置不需要进行回滚的异常类数组，当方法中抛出指定异常数组中的异常时，不进行事务回滚。例如： 指定单一异常类：@Transactional(noRollbackFor=RuntimeException.class) 指定多个异常类：@Transactional(noRollbackFor={RuntimeException.class, Exception.class})
noRollbackForClassName	该属性用于设置不需要进行回滚的异常类名称数组，当方法中抛出指定异常名称数组中的异常时，不进行事务回滚。例如： 指定单一异常类名称：@Transactional(noRollbackForClassName="RuntimeException") 指定多个异常类名称： @Transactional(noRollbackForClassName={"RuntimeException","Exception"})
propagation	该属性用于设置事务的传播行为，具体取值可参考表6-7。 例如：@Transactional(propagation=Propagation.NOT_SUPPORTED,readOnly=true)
isolation	该属性用于设置底层数据库的事务隔离级别，事务隔离级别用于处理多事务并发的情况，通常使用数据库的默认隔离级别即可，基本不需要进行设置
timeout	该属性用于设置事务的超时秒数，默认值为-1表示永不超时

 

Spring配置文件的支持

在Spring配置文件中需要添加如下代码以支持项目中的@Transactional注解

 

<tx:annotation-driven/>