DTP模型之二：（XA协议之二）jotm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>