（附源码gitHub下载地址）spring boot -jta-atomikos分布式事务

应用场景：双数据源，就是某些项目会涉及到两个数据源或者两个以上的数据源，这个多数据源的项目一般是数据同步，也就是把数据从另一个系统中，保存到另一个系统，两边的数据库又不一样，比如一个Mysql、一个Sql Server。但是不管是什么类型的数据库，我们都不管，直接连接就是。

为什么要使用分布式事务：顾名思义，事务就是回滚，比如如果一个在保存数据的时候，在A数据库已经保存，但是在保存数据在B的过程抛出异常，那么是不是应该全部回滚，把已经保存了的A、B数据库的数据全部回滚？答案是确定的。下面就解说：

pom.xml主要依赖：

       <dependency>
            <groupId>tk.mybatis</groupId>
            <artifactId>mapper-spring-boot-starter</artifactId>
            <version>2.0.0</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jta-atomikos</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.1.10</version>
        </dependency>

properties配置文件：

         #数据源一
         spring.datasource.primary.url=jdbc:mysql://localhost:3306/test
         spring.datasource.primary.username=root
         spring.datasource.primary.password=root
         spring.datasource.primary.driver-class-name=com.mysql.jdbc.Driver
         spring.datasource.primary.xa-data-source-class-name=com.alibaba.druid.pool.xa.DruidXADataSource
         
         #数据源二
         spring.datasource.secondary.url=jdbc:mysql://localhost:3306/test1
         spring.datasource.secondary.username=root
         spring.datasource.secondary.password=root
         spring.datasource.secondary.driver-class-name=com.mysql.jdbc.Driver
         spring.datasource.secondary.xa-data-source-class-name=com.alibaba.druid.pool.xa.DruidXADataSource

数据源的配置类：DataSourceConfig.class

import com.alibaba.druid.pool.xa.DruidXADataSource;

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;


@Configuration
public class DataSourceConfig {
    //这里一定要加主数据源的注解
    @Primary
    @Bean(name = "primaryProperty")
    @ConfigurationProperties(prefix = "spring.datasource.primary")
    public DruidXADataSource primaryDataSource() {
        return new DruidXADataSource();
    }
    
   //这里是第二个数据源
    @Bean(name = "secondaryProperty")
    @ConfigurationProperties(prefix = "spring.datasource.secondary")
    public DruidXADataSource secondaryDataSource() {
        return new DruidXADataSource();
    }
}

再分别配置他们的数据源：以便包扫描、事务交给jta-atomikos统一管理

主数据源配置类：

import com.alibaba.druid.pool.xa.DruidXADataSource;
import com.atomikos.jdbc.AtomikosDataSourceBean;

import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.SqlSessionTemplate;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;

import javax.sql.DataSource;

import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import tk.mybatis.spring.annotation.MapperScan;

@Configuration
@MapperScan(basePackages = {"com.example.dao.primary"}, sqlSessionTemplateRef = "primarySqlSessionTemplate")
public class PrimaryDBConfig {

    @Bean(name = "primaryDataSource")
    public DataSource dataSourceCar(@Qualifier("primaryProperty") DruidXADataSource druidXADataSource) {
        AtomikosDataSourceBean xaDataSource = new AtomikosDataSourceBean();
        xaDataSource.setXaDataSource(druidXADataSource);
        xaDataSource.setUniqueResourceName("primaryDataSource");
        return xaDataSource;
    }

    @Bean(name = "primarySqlSessionFactory")
    public SqlSessionFactory sqlSessionFactory(@Qualifier("primaryDataSource") DataSource dataSource)
            throws Exception {
        SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
        bean.setDataSource(dataSource);
        bean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:mapper/primary/*Mapper.xml"));//扫描指定目录的xml
        return bean.getObject();
    }

    @Bean(name = "primarySqlSessionTemplate")
    public SqlSessionTemplate sqlSessionTemplate(
            @Qualifier("primarySqlSessionFactory") SqlSessionFactory sqlSessionFactory) throws Exception {
        return new SqlSessionTemplate(sqlSessionFactory);
    }
}

同理，第二个数据源的配置SecondaryDBConfig.java

@Configuration
@MapperScan(basePackages = {"com.example.dao.secondary"}, sqlSessionTemplateRef = "secondarySqlSessionTemplate")
public class SecondaryDBConfig {

    @Bean(name = "secondaryDataSource")
    public DataSource dataSourceCar(@Qualifier("secondaryProperty") DruidXADataSource druidXADataSource) {
        AtomikosDataSourceBean xaDataSource = new AtomikosDataSourceBean();
        xaDataSource.setXaDataSource(druidXADataSource);
        xaDataSource.setUniqueResourceName("secondaryDataSource");
        return xaDataSource;
    }

    @Bean(name = "secondarySqlSessionFactory")
    public SqlSessionFactory sqlSessionFactory(@Qualifier("secondaryDataSource") DataSource dataSource)
            throws Exception {
        SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
        bean.setDataSource(dataSource);
        bean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:mapper/secondary/*Mapper.xml"));//扫描指定目录的xml
        return bean.getObject();
    }

    @Bean(name = "secondarySqlSessionTemplate")
    public SqlSessionTemplate sqlSessionTemplate(
            @Qualifier("secondarySqlSessionFactory") SqlSessionFactory sqlSessionFactory) throws Exception {
        return new SqlSessionTemplate(sqlSessionFactory);
    }
}

最后我们还需要配置事务管理的配置类：TransactionManagerConfig.java，以便把数据源一，数据源二全部交给jta-atomikos管理，实现分布式事务管理：

import com.atomikos.icatch.jta.UserTransactionImp;
import com.atomikos.icatch.jta.UserTransactionManager;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.DependsOn;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.jta.JtaTransactionManager;

import javax.transaction.TransactionManager;
import javax.transaction.UserTransaction;

@Configuration
public class TransactionManagerConfig {

    @Bean(name = "userTransaction")
    public UserTransaction userTransaction() throws Throwable {
        UserTransactionImp userTransactionImp = new UserTransactionImp();
        userTransactionImp.setTransactionTimeout(10000);
        return userTransactionImp;
    }

    @Bean(name = "atomikosTransactionManager")
    public TransactionManager atomikosTransactionManager() throws Throwable {
        UserTransactionManager userTransactionManager = new UserTransactionManager();
        userTransactionManager.setForceShutdown(false);
        return userTransactionManager;
    }

    @Bean(name = "transactionManager")
    @DependsOn({ "userTransaction", "atomikosTransactionManager" })
    public PlatformTransactionManager transactionManager() throws Throwable {
        return new JtaTransactionManager(userTransaction(),atomikosTransactionManager());
    }
}

　　最后我们在service类上加上注解：@Transactional(value = "transactionManager", rollbackFor = Exception.class)

当value = "transactionManager"，则是分布式事务的管理。至此，全部完成。

gitHub完整项目下载地址：https://gitee.com/qhThomas/springboot-mybatis-duria.git