JTA 分佈式事務

分佈式事務：一個事務涉及到要去操作位於不同服務器上的資源（數據庫），這時就要去保證每個數據庫裏面的狀態一致，如果出現異常還要去不同的數據庫裏面回滾。

這裏舉一個實際的例子就是 同時修改兩個數據庫的表中內容
1. 配置兩個datasource，利用JDBC模板方法配置兩個JdbcTemplate

<?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/aop
           http://www.springframework.org/schema/aop/spring-aop-2.5.xsd
           http://www.springframework.org/schema/tx 
           http://www.springframework.org/schema/tx/spring-tx-2.5.xsd">

    <!-- jotm 本地實例 -->
    <bean id="jotm" class="org.springframework.transaction.jta.JotmFactoryBean" />


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

    <!-- XAPool配置，內部包含了一個XA數據源，對應Database1數據庫 -->
    <bean id="db1" class="org.enhydra.jdbc.pool.StandardXAPoolDataSource"
        destroy-method="shutdown">
        <property name="dataSource">
            <!-- 內部XA數據源 -->
            <bean class="org.enhydra.jdbc.standard.StandardXADataSource"
                destroy-method="shutdown">
                <property name="transactionManager" ref="jotm" />
                <property name="driverName" value="com.mysql.jdbc.Driver" />
                <property name="url"
                    value="jdbc:mysql://192.168.1.28:3306/Database1?useUnicode=true&amp;characterEncoding=UTF-8" />
            </bean>
        </property>
        <property name="user" value="root" />
        <property name="password" value="123456" />
    </bean>

    <!-- 另一個XAPool配置，內部包含另一個XA數據源，對應Database2數據庫 -->
    <bean id="db2" 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="com.mysql.jdbc.Driver" />
                <property name="url"
                    value="jdbc:mysql://192.168.1.28:3306/Database2?useUnicode=true&amp;characterEncoding=UTF-8" />
            </bean>
        </property>
        <property name="user" value="root" />
        <property name="password" value="123456" />
    </bean>

    <!-- 配置訪問Database1數據源的Spring JDBC模板 -->
    <bean id="ds1" class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="db1"></property>
    </bean>

    <!-- 配置訪問Database2數據源的Spring JDBC模板 -->
    <bean id="ds2" class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="db2"></property>
    </bean>
</beans>

1. 在分佈式事務中使用這兩個datasource

    @Resource(name = "txManager")
    private JtaTransactionManager txManager;

    protected JdbcTemplate ds1_jdbcTemplate;
    protected JdbcTemplate ds2_jdbcTemplate;

然後再具體的method裏面：

UserTransaction userTx = this.txManager.getUserTransaction();
try{
    userTx.begin();
    ds1_jdbcTemplate.execute("update account set money='1300' where accountid=8");
    ds2_jdbcTemplate.execute("update account set money='1700' where accountid=8");
    userTx.commit();
}
catch(Exception e){
    System.out.println("捕獲到異常，進行回滾" + e.getMessage());
    e.printStackTrace();
    try{
        userTx.rollback();
    }catch (IllegalStateException e1) {
        System.out.println("IllegalStateException:" + e1.getMessage());
    }catch (SecurityException e1) {
        System.out.println("SecurityException:" + e1.getMessage());
    }catch (SystemException e1) { 
        System.out.println("SystemException:" + e1.getMessage());
    }
}