这种方式只适用于  

对于真正分布式应用不适用,原因在于 Atomikos需要获得所有数据源  统一进行事务管理

JTA(Java Transaction API)被称为Java事务API,是由Java语言提供的一套解决分布式事务的API标准

 XA协议

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1. XA协议是JTA的基础
2. XA协议最早由Tuxedo首先提出,并交给X/Open组织,作为资源管理器(数据库)与事务管理器的接口标准
3. XA协议采用两阶段提交方式来管理分布式事务,MySQL从5.x版本开始支XA协议

Atomikos事务管理器

3.1 Atomikos简介

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Atomikos是一款Java/JTA事务处理工具,在SpringBoot的官网文档的分布式事务处理中Atomikos作为一种分布式事务的解决方案.
文档地址: https://docs.spring.io/spring-boot/docs/2.1.18.RELEASE/reference/html/boot-features-jta.html

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从SpringBoot的官网可以看出,官网介绍非常简单,说了要想使用需要添加依赖
<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-jta-atomikos</artifactId>
</dependency>然后就没介绍一些更多细节,不过Atomikos相对来说比较简单,只需要一个核心API即可核心API介绍
1. AtomikosDataSourceBean1.1 这个类是Atomikos连接池的首选类1.2 如果要开启Atomikos JTA首选就是实例化此类1.3 接下来要做的就是实例化此类的对象,并设置对象的属性1.4 创建好此类对象后它会自动的加入到事务管理中1.5 所有通过此类获取的连接执行的SQL都会加入到JTA事务管理

Configuration
@MapperScan(basePackages = {"com.example.demo.mapper"},sqlSessionFactoryRef = "primarySqlSessionFactory")
public class DataSourceConfig1 {@Value("${spring.datasource.primary.url}")private String url;@Value("${spring.datasource.primary.username}")private String username;@Value("${spring.datasource.primary.password}")private String password;@Value("${spring.datasource.primary.driver-class-name}")private String driverClassName;@Primary@Bean(name="primaryDataSource")public DataSource primaryDataSource(){//return DataSourceBuilder.create().build();//将事务统一交给Atomikos处理   不要自己定义事务管理器AtomikosDataSourceBean ds = new AtomikosDataSourceBean();DruidXADataSource dds = new DruidXADataSource();dds.setUsername(username);dds.setPassword(password);dds.setUrl(url);dds.setDriverClassName(driverClassName);ds.setXaDataSource(dds);ds.setUniqueResourceName("primaryDataSource");return ds;}@Primary@Bean(name="primarySqlSessionFactory")public SqlSessionFactory primarySqlSessionFactory(@Qualifier("primaryDataSource") DataSource dataSource) throws Exception {SqlSessionFactoryBean bean=new SqlSessionFactoryBean();bean.setDataSource(dataSource);bean.setTypeAliasesPackage("com.example.demo.pojo");bean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:mappers/*Mapper.xml"));SqlSessionFactory sqlSessionFactory = bean.getObject();sqlSessionFactory.getConfiguration().setMapUnderscoreToCamelCase(true);//sqlSessionFactory.getConfiguration().setJdbcTypeForNull(JdbcType.NULL);return sqlSessionFactory;}@Primary@Bean(name="primarySqlSessionTemplate")public SqlSessionTemplate primarySqlSessionTemplate(@Qualifier("primarySqlSessionFactory")SqlSessionFactory sqlSessionFactory){return new SqlSessionTemplate(sqlSessionFactory);}@Primary@Bean(name="primaryJdbcTemplate")public JdbcTemplate primaryJdbcTemplate(@Qualifier("primaryDataSource")DataSource dataSource){return  new JdbcTemplate(dataSource);}//    @Bean(name="primaryTransactionManager")
//    public DataSourceTransactionManager primaryTransactionManager(@Qualifier("primaryDataSource")DataSource dataSource){
//        return new DataSourceTransactionManager(dataSource);
//    }}

@Configuration
@MapperScan(basePackages = {"com.example.demo.mapper2"},sqlSessionFactoryRef = "secondSqlSessionFactory")
public class DataSourceConfig2 {@Value("${spring.datasource.second.url}")private String url;@Value("${spring.datasource.second.username}")private String username;@Value("${spring.datasource.second.password}")private String password;@Value("${spring.datasource.second.driver-class-name}")private String driverClassName;@Bean(name="secondDataSource")//@ConfigurationProperties(prefix = "spring.datasource.second")public DataSource secondDataSource(){//return DataSourceBuilder.create().build();AtomikosDataSourceBean ds = new AtomikosDataSourceBean();DruidXADataSource dds = new DruidXADataSource();dds.setUsername(username);dds.setPassword(password);dds.setUrl(url);dds.setDriverClassName(driverClassName);ds.setXaDataSource(dds);ds.setUniqueResourceName("secondDataSource");return ds;}@Bean(name="secondSqlSessionFactory")public SqlSessionFactory secondSqlSessionFactory(@Qualifier("secondDataSource") DataSource dataSource) throws Exception {SqlSessionFactoryBean bean=new SqlSessionFactoryBean();bean.setDataSource(dataSource);bean.setTypeAliasesPackage("com.example.demo.pojo2");bean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:mappers2/*Mapper.xml"));SqlSessionFactory sqlSessionFactory = bean.getObject();sqlSessionFactory.getConfiguration().setMapUnderscoreToCamelCase(true);//sqlSessionFactory.getConfiguration().setJdbcTypeForNull(JdbcType.NULL);return sqlSessionFactory;}@Bean(name="secondSqlSessionTemplate")public SqlSessionTemplate secondSqlSessionTemplate(@Qualifier("secondSqlSessionFactory")SqlSessionFactory sqlSessionFactory){return new SqlSessionTemplate(sqlSessionFactory);}@Bean(name="secondJdbcTemplate")public JdbcTemplate secondJdbcTemplate(@Qualifier("secondDataSource")DataSource dataSource){return  new JdbcTemplate(dataSource);}//        @Bean(name="secondTransactionManager")
//        public DataSourceTransactionManager secondTransactionManager(@Qualifier("secondDataSource")DataSource dataSource){
//            return new DataSourceTransactionManager(dataSource);
//        }
}

上面用的druid连接池

<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>1.2.15</version>
</dependency>
<dependency>

使用时候

@Transactional  不要指定事务管理器  也不要自定义事务管理器

测试中 连接阿里云RDS服务器一直有问题