Spring分布式事务实现

分布式事务是指操作多个数据库之间的事务，spring的org.springframework.transaction.jta.JtaTransactionManager，提供了分布式事务支持。如果使用WAS的JTA支持，把它的属性改为WebSphere对应的TransactionManager。
在tomcat下，是没有分布式事务的，不过可以借助于第三方软件jotm（Java Open Transaction Manager ）和AtomikosTransactionsEssentials实现，在spring中分布式事务是通过jta（jotm，atomikos）来进行实现。
1、http://jotm.objectweb.org/
2、http://www.atomikos.com/Main/TransactionsEssentials

一、使用JOTM例子
(1)、Dao及实现

public interface GenericDao {

public int save(String ds, String sql, Object[] obj) throws Exception;

public int findRowCount(String ds, String sql);

}

public class GenericDaoImpl implements GenericDao{

private  JdbcTemplate jdbcTemplateA;
private  JdbcTemplate jdbcTemplateB;

public void setJdbcTemplateA(JdbcTemplate jdbcTemplate) {
this.jdbcTemplateA = jdbcTemplate;
}

public void setJdbcTemplateB(JdbcTemplate jdbcTemplate) {
this.jdbcTemplateB = jdbcTemplate;
}

public int save(String ds, String sql, Object[] obj) throws Exception{
if(null == ds || "".equals(ds)) return -1;
try{
if(ds.equals("A")){
return this.jdbcTemplateA.update(sql, obj);
}else{
return this.jdbcTemplateB.update(sql, obj);
}
}catch(Exception e){
e.printStackTrace();
throw new Exception("执行" + ds + "数据库时失败！");
}
}

public int findRowCount(String ds, String sql) {
if(null == ds || "".equals(ds)) return -1;

if(ds.equals("A")){
return this.jdbcTemplateA.queryForInt(sql);
}else{
return this.jdbcTemplateB.queryForInt(sql);
}
}

}

(2)、Service及实现

public interface UserService {

public void saveUser() throws Exception;

}

public class UserServiceImpl implements UserService{

private GenericDao genericDao;

public void setGenericDao(GenericDao genericDao) {
this.genericDao = genericDao;
}

public void saveUser() throws Exception {
String userName = "user_" + Math.round(Math.random()*10000);
System.out.println(userName);

StringBuilder sql = new StringBuilder();
sql.append(" insert into t_user(username, gender) values(?,?); ");
Object[] objs = new Object[]{userName,"1"};

genericDao.save("A", sql.toString(), objs);

sql.delete(0, sql.length());
sql.append(" insert into t_user(name, sex) values(?,?); ");
objs = new Object[]{userName,"男的"};//值超出范围
genericDao.save("B", sql.toString(), objs);
}

}

(3)、applicationContext-jotm.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:context="http://www.springframework.org/schema/context"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd"> 
<description>springJTA</description>

<!--指定Spring配置中用到的属性文件-->
<bean id="propertyConfig"
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
<list>
<value>classpath:jdbc.properties</value>
</list>
</property>
</bean>

<!-- JOTM实例 -->
<bean id="jotm" class="org.springframework.transaction.jta.JotmFactoryBean">
<property name="defaultTimeout" value="500000"/>
</bean>

<!-- JTA事务管理器 -->
<bean id="jtaTransactionManager" class="org.springframework.transaction.jta.JtaTransactionManager">
<property name="userTransaction" ref="jotm" />
</bean>

<!-- 数据源A -->
<bean id="dataSourceA" class="org.enhydra.jdbc.pool.StandardXAPoolDataSource" destroy-method="shutdown">
<property name="dataSource">
<bean class="org.enhydra.jdbc.standard.StandardXADataSource" destroy-method="shutdown">
<property name="transactionManager" ref="jotm"/>
<property name="driverName" value="${jdbc.driver}"/>
<property name="url" value="${jdbc.url}"/>
</bean>
</property>
<property name="user" value="${jdbc.username}"/>
<property name="password" value="${jdbc.password}"/>
</bean>

<!-- 数据源B -->
<bean id="dataSourceB" class="org.enhydra.jdbc.pool.StandardXAPoolDataSource" destroy-method="shutdown">
<property name="dataSource">
<bean class="org.enhydra.jdbc.standard.StandardXADataSource" destroy-method="shutdown">
<property name="transactionManager" ref="jotm"/>
<property name="driverName" value="${jdbc2.driver}"/>
<property name="url" value="${jdbc2.url}"/>
</bean>
</property>
<property name="user" value="${jdbc2.username}"/>
<property name="password" value="${jdbc2.password}"/>
</bean>

<bean id = "jdbcTemplateA"
class = "org.springframework.jdbc.core.JdbcTemplate">
<property name = "dataSource" ref="dataSourceA"/>
</bean>

<bean id = "jdbcTemplateB"
class = "org.springframework.jdbc.core.JdbcTemplate">
<property name = "dataSource" ref="dataSourceB"/>
</bean>

<!-- 事务切面配置 -->
<aop:config>
<aop:pointcut id="pointCut"
expression="execution(* com.logcd.service..*.*(..))"/><!-- 包及其子包下的所有方法 -->
<aop:advisor pointcut-ref="pointCut" advice-ref="txAdvice"/>

<aop:advisor pointcut="execution(* *..common.service..*.*(..))" advice-ref="txAdvice"/>
</aop:config>

<!-- 通知配置 -->
<tx:advice id="txAdvice" transaction-manager="jtaTransactionManager">
<tx:attributes>
<tx:method name="delete*" rollback-for="Exception"/>
<tx:method name="save*" rollback-for="Exception"/>
<tx:method name="update*" rollback-for="Exception"/>
<tx:method name="find*" read-only="true" rollback-for="Exception"/>
</tx:attributes>
</tx:advice>

<bean id="genericDao"
class="com.logcd.dao.impl.GenericDaoImpl" autowire="byName">
</bean>

<bean id="userService"
class="com.logcd.service.impl.UserServiceImpl" autowire="byName">
</bean>

</beans>

(4)、测试

public class TestUserService{

private static UserService userService;

@BeforeClass
public static void init(){
ApplicationContext app = new ClassPathXmlApplicationContext("applicationContext-jotm.xml");
userService = (UserService)app.getBean("userService");
}

@Test
public void save(){
System.out.println("begin...");
try{
userService.saveUser();
}catch(Exception e){
System.out.println(e.getMessage());
}
System.out.println("finish...");
}

}

二、关于使用atomikos实现
(1)、数据源配置

<bean id="dataSourceA" class="com.atomikos.jdbc.SimpleDataSourceBean" init-method="init" destroy-method="close">
<property name="uniqueResourceName">
<value>${datasource.uniqueResourceName}</value>
</property>
<property name="xaDataSourceClassName">
<value>${database.driver_class}</value>
</property>
<property name="xaDataSourceProperties">
<value>URL=${database.url};user=${database.username};password=${database.password}</value>
</property>
<property name="exclusiveConnectionMode">
<value>${connection.exclusive.mode}</value>
</property>
<property name="connectionPoolSize">
<value>${connection.pool.size}</value>
</property>
<property name="connectionTimeout">
<value>${connection.timeout}</value>
</property>
<property name="validatingQuery">
<value>SELECT 1</value>
</property>
</bean>

(2)、事务配置

<bean id="atomikosTransactionManager" class="com.atomikos.icatch.jta.UserTransactionManager"
init-method="init" destroy-method="close">
<property name="forceShutdown" value="true"/>
</bean>

<bean id="atomikosUserTransaction" class="com.atomikos.icatch.jta.UserTransactionImp">
<property name="transactionTimeout" value="${transaction.timeout}"/>
</bean>

<!-- JTA事务管理器 -->
<bean id="springTransactionManager" class="org.springframework.transaction.jta.JtaTransactionManager">
<property name="transactionManager" ref="atomikosTransactionManager"/>
<property name="userTransaction" ref="atomikosUserTransaction"/>
</bean>

<!-- 事务切面配置 -->
<aop:config>
<aop:pointcut id="serviceOperation"  expression="execution(* *..service*..*(..))"/>
<aop:advisor pointcut-ref="serviceOperation" advice-ref="txAdvice"/>
</aop:config>

<!-- 通知配置 -->
<tx:advice id="txAdvice" transaction-manager="springTransactionManager">
<tx:attributes>
<tx:method name="*" rollback-for="Exception"/>
</tx:attributes>
</tx:advice>