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:
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* 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
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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/>