Spring的初体验-5

一. Spring的编程式事务管理（非AOP的解决方案）

缺点：非业务代码会对目标业务代码造成侵入。

1. Spring配置文件（src/beans.xml）

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd">
        
	<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
        <property name="driverClassName" value="${jdbc.driverClassName}"/>
        <property name="url" value="${jdbc.url}"/>
        <property name="username" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
    </bean>
    
    <!-- jdbc事务管理器 -->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
    	<property name="dataSource" ref="dataSource"></property>
    </bean>
    
    <bean id="transactionTemplate" class="org.springframework.transaction.support.TransactionTemplate">
    	<property name="transactionManager" ref="transactionManager"></property>
    </bean>
     
	<context:property-placeholder location="jdbc.properties"/>
    
    <bean id="namedParameterJdbcTemplate" class="org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate">
    	<constructor-arg ref="dataSource"></constructor-arg>
    </bean>
	
	<bean id="bankDao" class="com.bee.dao.impl.BankDaoImpl">
		<property name="namedParameterJdbcTemplate" ref="namedParameterJdbcTemplate"></property>
	</bean> 
	
	<bean id="bankService" class="com.bee.service.impl.BankServiceImpl">
		<property name="bankDao" ref="bankDao"></property>
		<property name="transactionTemplate" ref="transactionTemplate"></property>
	</bean> 
</beans>

2. Service层

public class BankServiceImpl implements BankService{

	private BankDao bankDao;
	
	private TransactionTemplate transactionTemplate;
	
	public void setBankDao(BankDao bankDao) {
		this.bankDao = bankDao;
	}
	//注入事务
	public void setTransactionTemplate(TransactionTemplate transactionTemplate) {
		this.transactionTemplate = transactionTemplate;
	}

	//非业务代码侵入了业务代码
	@Override
	public void transferAccounts(final int count, final int userIdA, final int userIdB) {
		transactionTemplate.execute(new TransactionCallbackWithoutResult() {
			@Override
			protected void doInTransactionWithoutResult(TransactionStatus arg0) {
				bankDao.outMoney(count, userIdA);
				bankDao.inMoney(count, userIdB);				
			}
		});
	}
}

二. Spring的声明式事务管理（AOP解决方案）

注意：AOP只能作用于方法。

1. 使用XML配置文件声明事务（可批量处理实现类）

• Spring配置文件（src/beans.xml）

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop.xsd
        http://www.springframework.org/schema/tx
        http://www.springframework.org/schema/tx/spring-tx.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd">
        
	<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
        <property name="driverClassName" value="${jdbc.driverClassName}"/>
        <property name="url" value="${jdbc.url}"/>
        <property name="username" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
    </bean>
    
    <!-- jdbc事务管理器 -->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
    	<property name="dataSource" ref="dataSource"></property>
    </bean>
    
    <!-- 配置事务通知 -->
    <tx:advice id="txAdvice" transaction-manager="transactionManager">
    	<tx:attributes>  
            <tx:method name="insert*" propagation="REQUIRED" />  
            <tx:method name="update*" propagation="REQUIRED" />  
            <tx:method name="edit*" propagation="REQUIRED" />  
            <tx:method name="save*" propagation="REQUIRED" />  
            <tx:method name="add*" propagation="REQUIRED" />  
            <tx:method name="new*" propagation="REQUIRED" />  
            <tx:method name="set*" propagation="REQUIRED" />  
            <tx:method name="remove*" propagation="REQUIRED" />  
            <tx:method name="delete*" propagation="REQUIRED" />  
            <tx:method name="change*" propagation="REQUIRED" />  
            <tx:method name="get*" propagation="REQUIRED" read-only="true" />  
            <tx:method name="find*" propagation="REQUIRED" read-only="true" />  
            <tx:method name="load*" propagation="REQUIRED" read-only="true" />  
            <tx:method name="*" propagation="REQUIRED" read-only="true" />  
        </tx:attributes>  
    </tx:advice>
    
    <!-- 配置事务切面 -->
    <aop:config>
    	<!-- 配置切点：切入service层的方法。
    		扫描具体是匹配到包下的接口（看接口中定义的抽象方法）。 
    		注意Spring要求针对接口编程。
    	-->
    	<aop:pointcut id="serviceMethod" expression="execution(* com.bee.service.*.*(..))" />
    	<!-- 配置事务通知 -->
    	<aop:advisor advice-ref="txAdvice" pointcut-ref="serviceMethod"/>
    </aop:config>
    
	<context:property-placeholder location="jdbc.properties"/>
    
    <bean id="namedParameterJdbcTemplate" class="org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate">
    	<constructor-arg ref="dataSource"></constructor-arg>
    </bean>
	
	<bean id="bankDao" class="com.bee.dao.impl.BankDaoImpl">
		<property name="namedParameterJdbcTemplate" ref="namedParameterJdbcTemplate"></property>
	</bean> 
	
	<bean id="bankService" class="com.bee.service.impl.BankServiceImpl">
		<property name="bankDao" ref="bankDao"></property>
	</bean> 
	
</beans>

• Service层

public class BankServiceImpl implements BankService{

	private BankDao bankDao;
	//DI
	public void setBankDao(BankDao bankDao) {
		this.bankDao = bankDao;
	}
	
	@Override
	public void transferAccounts(int count, int userIdA, int userIdB) {
		bankDao.outMoney(count, userIdA);
		bankDao.inMoney(count, userIdB);				
	}
}

2. 使用注解声明事务（针对单个实现类）

• Spring配置文件（src/beans.xml）

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop.xsd
        http://www.springframework.org/schema/tx
        http://www.springframework.org/schema/tx/spring-tx.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd">
        
	<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
        <property name="driverClassName" value="${jdbc.driverClassName}"/>
        <property name="url" value="${jdbc.url}"/>
        <property name="username" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
    </bean>
    
    <!-- jdbc事务管理器 -->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
    	<property name="dataSource" ref="dataSource"></property>
    </bean>
    <!-- 声明注解事务 -->
    <tx:annotation-driven transaction-manager="transactionManager"/>
     
	<context:property-placeholder location="jdbc.properties"/>
    
    <bean id="namedParameterJdbcTemplate" class="org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate">
    	<constructor-arg ref="dataSource"></constructor-arg>
    </bean>
		
	<bean id="bankDao" class="com.bee.dao.impl.BankDaoImpl">
		<property name="namedParameterJdbcTemplate" ref="namedParameterJdbcTemplate"></property>
	</bean> 
	
	<bean id="bankService" class="com.bee.service.impl.BankServiceImpl">
		<property name="bankDao" ref="bankDao"></property>
	</bean> 
</beans>

• Service层

@Transactional
public class BankServiceImpl implements BankService{
	private BankDao bankDao;
	//DI
	public void setBankDao(BankDao bankDao) {
		this.bankDao = bankDao;
	}
	
	@Override
	public void transferAccounts(int count, int userIdA, int userIdB) {
		bankDao.outMoney(count, userIdA);
		bankDao.inMoney(count, userIdB);				
	}
}

三. 事务传播行为

Spring 中当一个 service 方法调用另外一个 service 方法的时候，因为每个 service 方法都有事务，这时候就出现了事务的嵌套，由此，就产生了事务传播行为。

在 Spring 中通过配置属性 propagation，来定义事务传播行为：

• PROPAGATION_REQUIRED：支持当前事务，如果当前没有事务，就新建一个事务。这是最常见的选择。
• PROPAGATION_SUPPORTS：支持当前事务，如果当前没有事务，就以非事务方式执行。
• PROPAGATION_MANDATORY：支持当前事务，如果当前没有事务，就抛出异常。
• PROPAGATION_REQUIRES_NEW：新建事务，如果当前存在事务，把当前事务挂起。
• PROPAGATION_NOT_SUPPORTED：以非事务方式执行操作，如果当前存在事务，就把当前事务挂起。
• PROPAGATION_NEVER：以非事务方式执行，如果当前存在事务，则抛出异常。

Spring中的常用配置：

<tx:attributes>
	<tx:method name="insert*" propagation="REQUIRED" />
	<tx:method name="update*" propagation="REQUIRED" />
	<tx:method name="edit*" propagation="REQUIRED" />
	<tx:method name="save*" propagation="REQUIRED" />
	<tx:method name="add*" propagation="REQUIRED" />
	<tx:method name="new*" propagation="REQUIRED" />
	<tx:method name="set*" propagation="REQUIRED" />
	<tx:method name="remove*" propagation="REQUIRED" />
	<tx:method name="delete*" propagation="REQUIRED" />
	<tx:method name="change*" propagation="REQUIRED" />
	<tx:method name="get*" propagation="REQUIRED" read-only="true" />
	<tx:method name="find*" propagation="REQUIRED" read-only="true" />
	<tx:method name="load*" propagation="REQUIRED" read-only="true" />
	<tx:method name="*" propagation="REQUIRED" read-only="true" />
</tx:attributes>