之前的 《spring 動(dòng)態(tài)切換获询、添加數(shù)據(jù)源實(shí)現(xiàn)以及源碼淺析》 中介紹了如何使用 spring 提供的 AbstractRoutingDataSource 配置多數(shù)據(jù)源，有了多數(shù)據(jù)源自然要管理事務(wù)的一致性仍翰。
上篇文章中提到過配置多數(shù)據(jù)源的兩種方式

1. 使用AbstractRoutingDataSource
2. 配置多個(gè) SqlSessionFactory

前言

閱讀了一下spring的源碼，由于 spring 事務(wù)的機(jī)制观话，在開啟事務(wù)之前spring 會(huì)去創(chuàng)建當(dāng)前數(shù)據(jù)源的 事務(wù)object予借，直到事務(wù)提交，spring 都不會(huì)在乎你是否切換了數(shù)據(jù)源频蛔。這就導(dǎo)致了灵迫，使用 AbstractRouting DataSource 方式開啟事務(wù)時(shí)，切換數(shù)據(jù)源不生效晦溪。
關(guān)于如何解決這個(gè)問題瀑粥，感興趣的朋友可以去閱讀一下：http://www.reibang.com/p/61e8961c6154

本文只討論上述第二種方式結(jié)合 atomikos 管理多數(shù)據(jù)源事務(wù)。

Atomikos

來自：http://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-jta.html

Atomikos is a popular open source transaction manager which can be embedded into your Spring Boot application. You can use thespring-boot-starter-jta-atomikos Starter to pull in the appropriate Atomikos libraries. Spring Boot auto-configures Atomikos and ensures that appropriate depends-on settings are applied to your Spring beans for correct startup and shutdown ordering.

By default, Atomikos transaction logs are written to a transaction-logs directory in your application’s home directory (the directory in which your application jar file resides). You can customize the location of this directory by setting a spring.jta.log-dir property in your application.properties file. Properties starting with spring.jta.atomikos.properties can also be used to customize the Atomikos UserTransactionServiceImp. See the AtomikosProperties Javadoc for complete details.

引入spring-boot-starter-jta-atomikos三圆，spring boot 為我們自動(dòng)配置
Atomikos狞换，我們可以通過 spring.jta.xxx 修改默認(rèn)配置。

Talk is cheap. Show me the code

• demo源碼：https://gitee.com/yintianwen7/taven-springboot-learning/tree/master/spring-atomikos
• 添加 maven 依賴

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jta-atomikos</artifactId>
        </dependency>

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.1.1</version>
        </dependency>

• application.properties

#spring.jta.log-dir=classpath:tx-logs
spring.jta.transaction-manager-id=txManager

spring.datasource.druid.system-db.name=system-db
spring.datasource.druid.system-db.url=jdbc:mysql://localhost:3306/test1?useSSL=false
spring.datasource.druid.system-db.username=root
spring.datasource.druid.system-db.password=taven753
spring.datasource.druid.system-db.initialSize=5
spring.datasource.druid.system-db.minIdle=5
spring.datasource.druid.system-db.maxActive=20
spring.datasource.druid.system-db.maxWait=60000
spring.datasource.druid.system-db.timeBetweenEvictionRunsMillis=60000
spring.datasource.druid.system-db.minEvictableIdleTimeMillis=30000
spring.datasource.druid.system-db.validationQuery=SELECT 1
spring.datasource.druid.system-db.validationQueryTimeout=10000
spring.datasource.druid.system-db.testWhileIdle=true
spring.datasource.druid.system-db.testOnBorrow=false
spring.datasource.druid.system-db.testOnReturn=false
spring.datasource.druid.system-db.poolPreparedStatements=true
spring.datasource.druid.system-db.maxPoolPreparedStatementPerConnectionSize=20
spring.datasource.druid.system-db.filters=stat,wall
spring.datasource.druid.system-db.connectionProperties=druid.stat.mergeSql=true;druid.stat.slowSqlMillis=5000
spring.datasource.druid.system-db.useGlobalDataSourceStat=true

spring.datasource.druid.business-db.name=business-db
spring.datasource.druid.business-db.url=jdbc:mysql://localhost:3306/test2?useSSL=false
spring.datasource.druid.business-db.username=root
spring.datasource.druid.business-db.password=taven753
spring.datasource.druid.business-db.initialSize=5
spring.datasource.druid.business-db.minIdle=5
spring.datasource.druid.business-db.maxActive=20
spring.datasource.druid.business-db.maxWait=60000
spring.datasource.druid.business-db.timeBetweenEvictionRunsMillis=60000
spring.datasource.druid.business-db.minEvictableIdleTimeMillis=30000
spring.datasource.druid.business-db.validationQuery=SELECT 1
spring.datasource.druid.business-db.validationQueryTimeout=10000
spring.datasource.druid.business-db.testWhileIdle=true
spring.datasource.druid.business-db.testOnBorrow=false
spring.datasource.druid.business-db.testOnReturn=false
spring.datasource.druid.business-db.poolPreparedStatements=true
spring.datasource.druid.business-db.maxPoolPreparedStatementPerConnectionSize=20
spring.datasource.druid.business-db.filters=stat,wall
spring.datasource.druid.business-db.connectionProperties=druid.stat.mergeSql=true;druid.stat.slowSqlMillis=5000
spring.datasource.druid.business-db.useGlobalDataSourceStat=true

• system 數(shù)據(jù)源的配置類

@Configuration
@MapperScan(basePackages = SystemDataSourceConfig.PACKAGE, sqlSessionFactoryRef = "systemSqlSessionFactory")
public class SystemDataSourceConfig {

    static final String PACKAGE = "com.gitee.taven.mapper.system";
    
    @Autowired
    private SystemProperties systemProperties;

    @Bean(name = "systemDataSource")
    @Primary
    public DataSource systemDataSource() {
        AtomikosDataSourceBean ds = new AtomikosDataSourceBean();
        ds.setXaProperties(PojoUtil.obj2Properties(systemProperties));
        ds.setXaDataSourceClassName("com.alibaba.druid.pool.xa.DruidXADataSource");
        ds.setUniqueResourceName("systemDataSource");
        ds.setPoolSize(5);
        ds.setTestQuery("SELECT 1");
        return ds;
    }

    @Bean
    @Primary
    public SqlSessionFactory systemSqlSessionFactory() throws Exception {
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(systemDataSource());
        return sqlSessionFactoryBean.getObject();
    }
    
}

• 更新于 2019.6.24舟肉，在簡友LT的幫助下修噪，發(fā)現(xiàn)了一個(gè)bug，由于MySQL的wait_timeout 機(jī)制度气，會(huì)導(dǎo)致數(shù)據(jù)庫連接在長時(shí)間未使用的情況（MySQL默認(rèn)是8小時(shí)）下失效
  雖然我們配置了Druid的檢查機(jī)制割按，但是還要在AtomikosDataSourceBean 的屬性上添加一個(gè)屬性，如下：

AtomikosDataSourceBean ds = new AtomikosDataSourceBean();
// 省略
ds.setTestQuery("SELECT 1");

• business 數(shù)據(jù)源的配置類同上
• 省略了 mybatis 代碼磷籍，通過service 測試事務(wù)适荣，拋出異常后，事務(wù)會(huì)回滾

@Service
public class UserService {

    @Autowired private UsersMapper usersMapper;
    
    @Autowired private UserInformationsMapper userInformationsMapper;
    
    @Transactional
    public void testJTA() {
        Users u = new Users();
        u.setUsername("hmj");
        u.setPassword("hmjbest");
        usersMapper.insertSelective(u);
        
        UserInformations ui = new UserInformations();
        ui.setUserid(666l);
        ui.setEmail("dsb");
        userInformationsMapper.insertSelective(ui);
        
//      int i = 10/0;
    }
    
}

本文Demo

Github, Gitee