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>springJTAdescription>


     <bean id="propertyConfig"
             class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
         <property name="locations">
             <list>
                 <value>classpath:jdbc.propertiesvalue>
             list>
         property>
     bean>


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


     <bean id="jtaTransactionManager" class="org.springframework.transaction.jta.JtaTransactionManager">
         <property name="userTransaction" ref="jotm" />
     bean>


     <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>


     <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>


     <aop:config>
         <aop:pointcut id="pointCut"
                 expression="execution(* com.logcd.service..*.*(..))"/>
         <aop:advisor pointcut-ref="pointCut" advice-ref="txAdvice"/>

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


     <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 1value>
     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>


 <bean id="springTransactionManager" class="org.springframework.transaction.jta.JtaTransactionManager">
     <property name="transactionManager" ref="atomikosTransactionManager"/>
     <property name="userTransaction" ref="atomikosUserTransaction"/>
 bean>


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


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

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