【Spring框架三】Spring常用注解之Transactional
编程技术 / houtizong 发布于 3年前 68
- 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
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@Documentedpublic @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
| 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/>
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