分布式事务的学习

解决分布式事务的理论方案

• 全局事务XA规范
• 最终一致性：2PC，TCC
• 可靠消息服务（例如rocketmq的事务消息；rabbitmq基于ack的消息确认）
• 最大努力通知

分布式事务场景有如下几种形式：

• 一个应用中操作多个数据库需要保证数据一致性
• 微服务不同模块操作同一个数据库需要保证数据一致性
• 微服务不同模块操作不同数据库需要保证数据一致性

理论落地实现技术-Atomikos

Atomikos是基于XA规范的Java实现版本JTA进行开发的一项技术，这项技术也比较成熟了。针对mysql数据库Atomikos只有在InnoDB存储引擎下才有效，针对MyISAM就无法控制事务了，开发的时候需要注意这点

XA是强一致性事务，性能不佳，互联网项目中中的应该不多，因此Atomikos更适合在一个单体应用中对多个数据源进行分布式事务

使用Atomikos开发，必须将不同数据源的mapper进行分包管理，也即不同数据源的Dao层放在不同的包下，这样mybatis的mapperScan扫描不同包下就可以获得正确的连接，建议将mapper的xml映射，实体类也进行分包管理

Atomikos和Spring整合

1.引入依赖

<dependency>
    <groupId>javax.transaction</groupId>
    <artifactId>jta</artifactId>
    <version>1.1</version>
</dependency>
<dependency>
    <groupId>com.atomikos</groupId>
    <artifactId>atomikos-util</artifactId>
    <version>4.0.6</version>
</dependency>
<dependency>
    <groupId>com.atomikos</groupId>
    <artifactId>transactions</artifactId>
    <version>4.0.6</version>
</dependency>
<dependency>
    <groupId>com.atomikos</groupId>
    <artifactId>transactions-api</artifactId>
    <version>4.0.6</version>
</dependency>
<dependency>
    <groupId>com.atomikos</groupId>
    <artifactId>transactions-jdbc</artifactId>
    <version>4.0.6</version>
</dependency>
<dependency>
    <groupId>com.atomikos</groupId>
    <artifactId>transactions-jta</artifactId>
    <version>4.0.6</version>
</dependency>

2.多个数据源连接信息配置

# 数据源1
jdbc.driverClass=com.mysql.jdbc.Driver
jdbc.jdbcUrl=jdbc:mysql:///ssm_crud?useSSl=false&characterEncoding=utf-8
jdbc.user=root
jdbc.password=root

# 数据源2
jdbc.shop.driverClass=com.mysql.jdbc.Driver
jdbc.shop.jdbcUrl=jdbc:mysql:///shop?useSSl=false&characterEncoding=utf-8
jdbc.shop.user=root
jdbc.shop.password=root

3.在spring的application.properties文件中配置如下内容

• 配置dataSource，这里需要使用AtomikosDataSourceBean

<!-- 引入jdbc.properties文件 -->
<context:property-placeholder location="classpath:jdbc.properties"/>

<!--这里配置一个抽象的bean 将数据源一些共有配置抽取出来，不是必须这样配置，只是为了抽出共有配置-->
<bean id="abstractXADataSource" class="com.atomikos.jdbc.AtomikosDataSourceBean" init-method="init" destroy-method="close" abstract="true">
    <property name="xaDataSourceClassName" value="com.mysql.jdbc.jdbc2.optional.MysqlXADataSource"/>
    <property name="maxPoolSize" value="30"/>
    <property name="minPoolSize" value="10"/>
    <property name="borrowConnectionTimeout" value="60"/>
    <property name="reapTimeout" value="20"/>
    <property name="maxIdleTime" value="60"/>
    <property name="maintenanceInterval" value="60"/>
</bean>
    <!--数据库1基本配置-->
    <bean id="dataSourceOne" parent="abstractXADataSource">
        <property name="uniqueResourceName" value="dataSourceOne"/>
        <!--数据库驱动-->
        <property name="xaProperties">
            <props>
                <prop key="url">${jdbc.jdbcUrl}</prop>
                <prop key="user">${jdbc.user}</prop>
                <prop key="password">${jdbc.password}</prop>
            </props>
        </property>
    </bean>
    <!--数据库2基本配置-->
    <bean id="dataSourceTwo" parent="abstractXADataSource">
        <property name="uniqueResourceName" value="dataSourceTwo"/>
        <!--数据库驱动-->
        <property name="xaProperties">
            <props>
                <prop key="url">${jdbc.shop.jdbcUrl}</prop>
                <prop key="user">${jdbc.shop.user}</prop>
                <prop key="password">${jdbc.shop.password}</prop>
            </props>
        </property>
</bean>

• 配置sqlSessionFactory (mapperLocations，typeAliasesPackage也可以配置不同的路径)

<!--有几个数据源就需要配置几个sqlSessionFactory-->
<bean id="sqlSessionFactoryOne" class="org.mybatis.spring.SqlSessionFactoryBean">
    <property name="configLocation" value="classpath:mybatis/sqlMapConfig.xml"></property>
    <property name="dataSource" ref="dataSourceOne"></property>
    <!-- 指定mybatis，mapper文件的位置 -->
    <property name="mapperLocations" value="classpath:mapper/*.xml"></property>
    <!-- 配置实体类别名 -->
    <property name="typeAliasesPackage" value="cn.lynu.model"></property>
</bean>
<bean id="sqlSessionFactoryTwo" class="org.mybatis.spring.SqlSessionFactoryBean">
    <property name="configLocation" value="classpath:mybatis/sqlMapConfig.xml"></property>
    <property name="dataSource" ref="dataSourceTwo"></property>
    <!-- 指定mybatis，mapper文件的位置 -->
    <property name="mapperLocations" value="classpath:mapper/*.xml"></property>
    <!-- 配置实体类别名 -->
    <property name="typeAliasesPackage" value="cn.lynu.model"></property>
</bean>

• 配置mapper扫描器（注意这里basePackage扫描的路径）

<!--有几个数据源就需要配置几个mapper扫描器-->
<bean id="mapperScannerConfigurerOne" class="org.mybatis.spring.mapper.MapperScannerConfigurer">
    <property name="basePackage" value="cn.lynu.mapper"></property>
    <property name="sqlSessionFactoryBeanName" value="sqlSessionFactoryOne"></property>
</bean>
<bean id="mapperScannerConfigurerTwo" class="org.mybatis.spring.mapper.MapperScannerConfigurer">
    <property name="basePackage" value="cn.lynu.shopmapper"></property>
    <property name="sqlSessionFactoryBeanName" value="sqlSessionFactoryTwo"></property>
</bean>

• 配置事务管理

<!--配置atomikos事务管理器-->
<bean id="atomikosTransactionManager" class="com.atomikos.icatch.jta.UserTransactionManager" init-method="init" destroy-method="close">
    <property name="forceShutdown" value="false"/>
</bean>
<!--配置atomikos事务-->
<bean id="atomikosUserTransaction" class="com.atomikos.icatch.jta.UserTransactionImp">
    <property name="transactionTimeout" value="300"/>
</bean>
<!--配置spring与jta事务整合-->
<bean id="springTransactionManager" class="org.springframework.transaction.jta.JtaTransactionManager">
    <property name="transactionManager" ref="atomikosTransactionManager"/>
    <property name="userTransaction" ref="atomikosUserTransaction"/>
    <property name="allowCustomIsolationLevels" value="true"/>
</bean>

• 配置事务切面，这里使用的是切面的方式配置事务，实际上使用注解配置也可以

<!-- 配置通知 -->
<tx:advice id="txAdvice" transaction-manager="springTransactionManager">
    <tx:attributes>
        <!-- 匹配业务类中的方法 -->
        <tx:method name="save*" propagation="REQUIRED"/>
        <tx:method name="insert*" propagation="REQUIRED"/>
        <tx:method name="update*" propagation="REQUIRED"/>
        <tx:method name="delete*" propagation="REQUIRED"/>
        <tx:method name="find*" propagation="SUPPORTS" read-only="true"/>
        <tx:method name="select*" propagation="SUPPORTS" read-only="true"/>
        <tx:method name="get*" propagation="SUPPORTS" read-only="true"/>
    </tx:attributes>
</tx:advice>
        
<!-- 配置aop -->
<aop:config>
    <!-- 配置切点 -->
    <aop:pointcut expression="execution(* cn.lynu.service.*.*(..))" id="cut"/>
    <!-- 配置切面 -->
    <aop:advisor advice-ref="txAdvice" pointcut-ref="cut"/>
</aop:config>

如果是注解方式就如下配置：

<tx:annotation-driven transaction-manager="springTransactionManager"/>

重点就是这里的transaction-manager

接下来就可以进行测试了：

package cn.lynu.service;

import cn.lynu.mapper.EmployeeMapper;
import cn.lynu.model.Employee;
import cn.lynu.model.ShopProduct;
import cn.lynu.shopmapper.ShopProductMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.math.BigDecimal;

@Service
public class AtomikosService {

    @Autowired
    private EmployeeMapper employeeMapper;
    @Autowired
    private ShopProductMapper shopProductMapper;

    public void saveMethod() {
        ShopProduct product = new ShopProduct();
        product.setPname("测试1");
        product.setPprice(new BigDecimal("100"));
        product.setStock(100);
        shopProductMapper.insertProduct(product);


        Employee employee = new Employee();
        employee.setEmpName("测试1");
        employee.setEmpSex("1");
        employee.setEmpEmail("123@qq.com");
        employee.setdId(1);
        employeeMapper.insertSelective(employee);
        
        int i = 1 / 0;
    }
}

查看运行日志，出现如下内容就表示分布式事务正常回滚

Atomikos和SpringBoot整合

这里我用的是Mybatis-Plus，Mybatis配置方法也类似，可以参考：springboot jta atomikos实现分布式事物管理

1.引入依赖

<!--使用atomikos实现分布式事务-->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-jta-atomikos</artifactId>
</dependency>

2.修改SpringBoot配置文件

spring:
  # 数据源配置
  datasource:
    databases1:
#      type: com.alibaba.druid.pool.DruidDataSource
      driver-class-name: com.mysql.jdbc.Driver
      url: jdbc:mysql:///ssm_crud?useSSl=false&characterEncoding=utf-8
      username: root
      password: root
    databases2:
#      type: com.alibaba.druid.pool.DruidDataSource
      driver-class-name: com.mysql.jdbc.Driver
      url: jdbc:mysql:///shop?useSSl=false&characterEncoding=utf-8
      username: root
      password: root

mybatis-plus:
  #Mapper扫描在MyBatisPlusConfigDS.java配置类中进行了配置
  #实体扫描，多个package用逗号或者分号分隔
  typeAliasesPackage: com.ds.entity
  global-config:
    db-config:
      #主键类型 AUTO:"数据库ID自增", INPUT:"用户输入ID", ID_WORKER:"全局唯一ID (默认,数字类型唯一ID)", UUID:"全局唯一ID UUID";
      id-type: AUTO
      #字段策略 IGNORED:"忽略判断", NOT_NULL:"非 NULL 判断"), NOT_EMPTY:"非空判断"
      field-strategy: NOT_NULL
      #是否开启大写命名，默认false不开启
      #capital-mode: true
  configuration:
    #配置返回数据库(column下划线命名&&返回java实体是驼峰命名)，自动匹配无需as（没开启这个，SQL需要写as： select user_id as userId）
    map-underscore-to-camel-case: true
    cache-enabled: false
    #配置JdbcTypeForNull, oracle数据库必须配置
    jdbc-type-for-null: 'null'
    #打印sql日志
#    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

3.Mybatis-Plus配置类

因为有两个数据源需要控制分布式事务，所以就需要写两个配置类，并且将basePackages扫描不同包下的mapper，这里也需要对不同数据源的Dao层进行分包，也建议将mapper的xml映射，实体类也进行分包管理

import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;
import com.baomidou.mybatisplus.extension.plugins.PerformanceInterceptor;
import com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean;
import com.mysql.jdbc.jdbc2.optional.MysqlXADataSource;
import org.apache.ibatis.plugin.Interceptor;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionTemplate;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.autoconfigure.jdbc.DataSourceProperties;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.jta.atomikos.AtomikosDataSourceBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;

import javax.sql.DataSource;

@Configuration
// 扫描的Dao层 多个数据源对应的Mapper文件以及XML文件需要分开配置(放在不同的包下) 如果放在同一个文件夹会报错
@MapperScan(basePackages = "com.ds.mapper", sqlSessionTemplateRef = "ds1SqlSessionTemplate")
public class MyBatisPlusConfigDS1 {

    /**
     * 数据源1配置信息(url password username...)
     */
    @Bean(name = "ds1DataSourceProperties")
    @ConfigurationProperties(prefix = "spring.datasource.databases1")
    public DataSourceProperties ds1DataSourceProperties() {
        return new DataSourceProperties();
    }

    /**
     * 配置数据源1
     * @param config 数据源配置信息
     * @return
     */
    @Primary
    @Bean(name = "ds1DataSource")
    public DataSource ds1DataSource(@Qualifier("ds1DataSourceProperties") DataSourceProperties config) {
        // 创建Mysql实现XA规范的分布式数据源
        MysqlXADataSource mysqlXaDataSource = new MysqlXADataSource();
        // 设置连接信息
        mysqlXaDataSource.setUrl(config.getUrl());
        mysqlXaDataSource.setPinGlobalTxToPhysicalConnection(true);
        mysqlXaDataSource.setPassword(config.getPassword());
        mysqlXaDataSource.setUser(config.getUsername());
        mysqlXaDataSource.setPinGlobalTxToPhysicalConnection(true);

		// 数据源改为Atomikos，将事务交给Atomikos统一管理
        AtomikosDataSourceBean xaDataSource = new AtomikosDataSourceBean();
        xaDataSource.setXaDataSource(mysqlXaDataSource);
		// Druid对于XA的支持,将上面代码注释,打开以下注释
		/*DruidXADataSource druidXADataSource = new DruidXADataSource();
        druidXADataSource.setUrl(config.getUrl());
        druidXADataSource.setPassword(config.getPassword());
        druidXADataSource.setUsername(config.getUsername());
        AtomikosDataSourceBean xaDataSource = new AtomikosDataSourceBean();
        xaDataSource.setXaDataSource(druidXADataSource);*/
		
        xaDataSource.setUniqueResourceName("ds1DataSource");

//        xaDataSource.setMinPoolSize(config.getMinPoolSize());
//        xaDataSource.setMaxPoolSize(config.getMaxPoolSize());
//        xaDataSource.setMaxLifetime(config.getMaxLifetime());
//        xaDataSource.setBorrowConnectionTimeout(config.getBorrowConnectionTimeout());
//        xaDataSource.setLoginTimeout(config.getLoginTimeout());
//        xaDataSource.setMaintenanceInterval(config.getMaintenanceInterval());
//        xaDataSource.setMaxIdleTime(config.getMaxIdleTime());
//        xaDataSource.setTestQuery(config.getTestQuery());
        return xaDataSource;
    }

    /**
     * 配置数据源1的sqlSessionFactory
     * 使用MybatisPlus的MybatisSqlSessionFactoryBean 替换Mybatis的SqlSessionFactoryBean
     * @param dataSource 数据源
     * @return
     * @throws Exception
     */
    @Bean(name = "ds1SqlSessionFactory")
    public SqlSessionFactory ds1SqlSessionFactory(@Qualifier("ds1DataSource") DataSource dataSource)
            throws Exception {
        MybatisSqlSessionFactoryBean sqlSessionFactoryBean = new MybatisSqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(dataSource);
        sqlSessionFactoryBean.setPlugins(new Interceptor[]{
                new PaginationInterceptor(), // 分页插件
                new PerformanceInterceptor().setFormat(true) // SQL格式化插件
        });
        // 配置为扫描数据源1所有的mapper
        sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:/com/ds/mapper/*.xml"));
        return sqlSessionFactoryBean.getObject();
    }

    /**
     * 配置数据源1的SqlSessionTemplate
     * @param sqlSessionFactory 数据源1的sqlSessionFactory
     */
    @Bean(name = "ds1SqlSessionTemplate")
    public SqlSessionTemplate ds1SqlSessionTemplate(@Qualifier("ds1SqlSessionFactory") SqlSessionFactory sqlSessionFactory) {
        return new SqlSessionTemplate(sqlSessionFactory);
    }
    
}

import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;
import com.baomidou.mybatisplus.extension.plugins.PerformanceInterceptor;
import com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean;
import com.mysql.jdbc.jdbc2.optional.MysqlXADataSource;
import org.apache.ibatis.plugin.Interceptor;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionTemplate;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.autoconfigure.jdbc.DataSourceProperties;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.jta.atomikos.AtomikosDataSourceBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;

import javax.sql.DataSource;
import java.sql.SQLException;

@Configuration
@MapperScan(basePackages = "com.ds.mapper2", sqlSessionTemplateRef = "ds2SqlSessionTemplate")
public class MyBatisPlusConfigDS2 {

    @Bean(name = "ds2DataSourceProperties")
    @ConfigurationProperties(prefix = "spring.datasource.databases2")
    public DataSourceProperties ds1DataSourceProperties() {
        return new DataSourceProperties();
    }

    // 配置数据源
    @Bean(name = "ds2DataSource")
    public DataSource ds2DataSource(@Qualifier("ds2DataSourceProperties") DataSourceProperties config) throws SQLException {
        MysqlXADataSource mysqlXaDataSource = new MysqlXADataSource();
        mysqlXaDataSource.setUrl(config.getUrl());
        mysqlXaDataSource.setPinGlobalTxToPhysicalConnection(true);
        mysqlXaDataSource.setPassword(config.getPassword());
        mysqlXaDataSource.setUser(config.getUsername());
        mysqlXaDataSource.setPinGlobalTxToPhysicalConnection(true);

        AtomikosDataSourceBean xaDataSource = new AtomikosDataSourceBean();
        xaDataSource.setXaDataSource(mysqlXaDataSource);
		
		// Druid对于XA的支持,将上面代码注释,打开以下注释
		/*DruidXADataSource druidXADataSource = new DruidXADataSource();
        druidXADataSource.setUrl(config.getUrl());
        druidXADataSource.setPassword(config.getPassword());
        druidXADataSource.setUsername(config.getUsername());
        AtomikosDataSourceBean xaDataSource = new AtomikosDataSourceBean();
        xaDataSource.setXaDataSource(druidXADataSource);*/
		
        xaDataSource.setUniqueResourceName("ds2DataSource");

//        xaDataSource.setMinPoolSize(config.getMinPoolSize());
//        xaDataSource.setMaxPoolSize(config.getMaxPoolSize());
//        xaDataSource.setMaxLifetime(config.getMaxLifetime());
//        xaDataSource.setBorrowConnectionTimeout(config.getBorrowConnectionTimeout());
//        xaDataSource.setLoginTimeout(config.getLoginTimeout());
//        xaDataSource.setMaintenanceInterval(config.getMaintenanceInterval());
//        xaDataSource.setMaxIdleTime(config.getMaxIdleTime());
//        xaDataSource.setTestQuery(config.getTestQuery());
        return xaDataSource;
    }

    @Bean(name = "ds2SqlSessionFactory")
    public SqlSessionFactory ds2SqlSessionFactory(@Qualifier("ds2DataSource") DataSource dataSource)
            throws Exception {
        MybatisSqlSessionFactoryBean sqlSessionFactoryBean = new MybatisSqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(dataSource);
        sqlSessionFactoryBean.setPlugins(new Interceptor[]{
                new PaginationInterceptor(), // 分页插件
                new PerformanceInterceptor().setFormat(true) // SQL格式化插件
        });
        sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:/com/ds/mapper2/*.xml"));
        return sqlSessionFactoryBean.getObject();
    }

    @Bean(name = "ds2SqlSessionTemplate")
    public SqlSessionTemplate ds2SqlSessionTemplate(
            @Qualifier("ds2SqlSessionFactory") SqlSessionFactory sqlSessionFactory) {
        return new SqlSessionTemplate(sqlSessionFactory);
    }

}

不同数据库连接池对Atomikos的支持

默认的MysqlXADataSource是支持XA规范的；而我们常用的数据库连接池如：HikariCP，druid，dbcp，c3p0等貌似有些还未支持，具体情况如下图：

理论落地实现技术-Seata

Seata官网

Seata是阿里开源的分布式，比较适合在分布式微服务项目中使用，如SpringCloud，Dubbo，官方也给出一些整合的案例

Seata中有TC，TM，RM的概念解释如下：

TC (Transaction Coordinator) - 事务协调者：维护全局和分支事务的状态，驱动全局事务提交或回滚。Seata提供实现好的seata-server作为TC。

TM (Transaction Manager) - 事务管理器：定义全局事务的范围：开始全局事务、提交或回滚全局事务。

RM (Resource Manager) - 资源管理器：管理分支事务处理的资源，与TC交谈以注册分支事务和报告分支事务的状态，并驱动分支事务提交或回滚。RM更多表示的就是每一个数据源。

TC已经由Seata提供了，我们只需要将从下载地址后配置运行即可，在项目中配置还需要我们配置TC和RM，这两者通过jar包的方式引入项目

Seata和SpringCloud整合

1.修改seata-server配置并运行

主要修改的是conf目录下的registry.conf，file.conf这两个文件。registry.conf只要配置注册中心和配置中心，Seata的注册中心可以是file 、nacos 、eureka、redis、zk、consul、etcd3、sofa类型，而配置中心可以是file、nacos 、apollo、zk、consul、etcd3这几种类型，如果我们将配置中心使用file类型，那么就需要修改file.conf这个文件了。这里记录的就是用nacos作为Seata注册中心，file作为配置中心的方案，如果需要将配置中心也使用nacos就需要修改conf/nacos-config.txt，修改后运行conf/nacos-config.sh脚本，更详细可以参看[文档](nacos (seata.io))

这里我们使用的是Seata 0.9.0版本的 seata-server-0.9.0

registry.conf：

registry {
  # file 、nacos 、eureka、redis、zk、consul、etcd3、sofa
  # 这里将注册中心type改为naccos
  type = "nacos"

  # 配置正确的naocs地址
  nacos {
    serverAddr = "localhost:8848"
    namespace = ""
    cluster = "default"
  }
  eureka {
    serviceUrl = "http://localhost:8761/eureka"
    application = "default"
    weight = "1"
  }
  redis {
    serverAddr = "localhost:6379"
    db = "0"
  }
  zk {
    cluster = "default"
    serverAddr = "127.0.0.1:2181"
    session.timeout = 6000
    connect.timeout = 2000
  }
  consul {
    cluster = "default"
    serverAddr = "127.0.0.1:8500"
  }
  etcd3 {
    cluster = "default"
    serverAddr = "http://localhost:2379"
  }
  sofa {
    serverAddr = "127.0.0.1:9603"
    application = "default"
    region = "DEFAULT_ZONE"
    datacenter = "DefaultDataCenter"
    cluster = "default"
    group = "SEATA_GROUP"
    addressWaitTime = "3000"
  }
  file {
    name = "file.conf"
  }
}

config {
  # file、nacos 、apollo、zk、consul、etcd3
  # 使用file类型的配置中心
  type = "file"

  nacos {
    serverAddr = "localhost"
    namespace = ""
  }
  consul {
    serverAddr = "127.0.0.1:8500"
  }
  apollo {
    app.id = "seata-server"
    apollo.meta = "http://192.168.1.204:8801"
  }
  zk {
    serverAddr = "127.0.0.1:2181"
    session.timeout = 6000
    connect.timeout = 2000
  }
  etcd3 {
    serverAddr = "http://localhost:2379"
  }
  # 因为使用了file类型的配置中心，所以接下来就需要修改file.conf文件
  file {
    name = "file.conf"
  }
}

file.conf：

这里我们使用数据库持久化配置信息，并且vgroup_mapping.xxx配置的值很关键，值的内容无所谓但是之后我们会用到，这里配置的my_tx_group并没什么特殊意义

transport {
  # tcp udt unix-domain-socket
  type = "TCP"
  #NIO NATIVE
  server = "NIO"
  #enable heartbeat
  heartbeat = true
  #thread factory for netty
  thread-factory {
    boss-thread-prefix = "NettyBoss"
    worker-thread-prefix = "NettyServerNIOWorker"
    server-executor-thread-prefix = "NettyServerBizHandler"
    share-boss-worker = false
    client-selector-thread-prefix = "NettyClientSelector"
    client-selector-thread-size = 1
    client-worker-thread-prefix = "NettyClientWorkerThread"
    # netty boss thread size,will not be used for UDT
    boss-thread-size = 1
    #auto default pin or 8
    worker-thread-size = 8
  }
  shutdown {
    # when destroy server, wait seconds
    wait = 3
  }
  serialization = "seata"
  compressor = "none"
}
service {
  #vgroup->rgroup 这里的值很关键，值的内容无所谓但是之后我们会用到，这里用的my_tx_group并没什么特殊意义
  vgroup_mapping.my_test_tx_group = "my_tx_group"
  #only support single node
  default.grouplist = "localhost:8091"
  #degrade current not support
  enableDegrade = false
  #disable
  disable = false
  #unit ms,s,m,h,d represents milliseconds, seconds, minutes, hours, days, default permanent
  max.commit.retry.timeout = "-1"
  max.rollback.retry.timeout = "-1"
}

client {
  async.commit.buffer.limit = 10000
  lock {
    retry.internal = 10
    retry.times = 30
  }
  report.retry.count = 5
  tm.commit.retry.count = 1
  tm.rollback.retry.count = 1
}

## transaction log store
store {
  ## store mode: file、db
  # 使用数据库持久化配置信息
  mode = "db"

  ## file store
  file {
    dir = "sessionStore"

    # branch session size , if exceeded first try compress lockkey, still exceeded throws exceptions
    max-branch-session-size = 16384
    # globe session size , if exceeded throws exceptions
    max-global-session-size = 512
    # file buffer size , if exceeded allocate new buffer
    file-write-buffer-cache-size = 16384
    # when recover batch read size
    session.reload.read_size = 100
    # async, sync
    flush-disk-mode = async
  }

  ## database store
  # 配置正确的数据库信息
  db {
    ## the implement of javax.sql.DataSource, such as DruidDataSource(druid)/BasicDataSource(dbcp) etc.
    datasource = "dbcp"
    ## mysql/oracle/h2/oceanbase etc.
    db-type = "mysql"
    driver-class-name = "com.mysql.jdbc.Driver"
    url = "jdbc:mysql://localhost:3306/seata"
    user = "root"
    password = "root"
    min-conn = 1
    max-conn = 3
    global.table = "global_table"
    branch.table = "branch_table"
    lock-table = "lock_table"
    query-limit = 100
  }
}
lock {
  ## the lock store mode: local、remote
  mode = "remote"

  local {
    ## store locks in user's database
  }

  remote {
    ## store locks in the seata's server
  }
}
recovery {
  #schedule committing retry period in milliseconds
  committing-retry-period = 1000
  #schedule asyn committing retry period in milliseconds
  asyn-committing-retry-period = 1000
  #schedule rollbacking retry period in milliseconds
  rollbacking-retry-period = 1000
  #schedule timeout retry period in milliseconds
  timeout-retry-period = 1000
}

transaction {
  undo.data.validation = true
  undo.log.serialization = "jackson"
  undo.log.save.days = 7
  #schedule delete expired undo_log in milliseconds
  undo.log.delete.period = 86400000
  undo.log.table = "undo_log"
}

## metrics settings
metrics {
  enabled = false
  registry-type = "compact"
  # multi exporters use comma divided
  exporter-list = "prometheus"
  exporter-prometheus-port = 9898
}

support {
  ## spring
  spring {
    # auto proxy the DataSource bean
    datasource.autoproxy = false
  }
}

因为需要在数据库持久化，所以就需要在数据库中提前生成表结构，建表语句在conf/db_store.sql，内容如下：

-- the table to store GlobalSession data
drop table if exists `global_table`;
create table `global_table` (
  `xid` varchar(128)  not null,
  `transaction_id` bigint,
  `status` tinyint not null,
  `application_id` varchar(32),
  `transaction_service_group` varchar(32),
  `transaction_name` varchar(128),
  `timeout` int,
  `begin_time` bigint,
  `application_data` varchar(2000),
  `gmt_create` datetime,
  `gmt_modified` datetime,
  primary key (`xid`),
  key `idx_gmt_modified_status` (`gmt_modified`, `status`),
  key `idx_transaction_id` (`transaction_id`)
);

-- the table to store BranchSession data
drop table if exists `branch_table`;
create table `branch_table` (
  `branch_id` bigint not null,
  `xid` varchar(128) not null,
  `transaction_id` bigint ,
  `resource_group_id` varchar(32),
  `resource_id` varchar(256) ,
  `lock_key` varchar(128) ,
  `branch_type` varchar(8) ,
  `status` tinyint,
  `client_id` varchar(64),
  `application_data` varchar(2000),
  `gmt_create` datetime,
  `gmt_modified` datetime,
  primary key (`branch_id`),
  key `idx_xid` (`xid`)
);

-- the table to store lock data
drop table if exists `lock_table`;
create table `lock_table` (
  `row_key` varchar(128) not null,
  `xid` varchar(96),
  `transaction_id` long ,
  `branch_id` long,
  `resource_id` varchar(256) ,
  `table_name` varchar(32) ,
  `pk` varchar(36) ,
  `gmt_create` datetime ,
  `gmt_modified` datetime,
  primary key(`row_key`)
);

当这两个配置文件修改完成之后运行bin/seata-server.sh/.bat就可以启动Seata-Server即可

2.在每一个涉及到分布式事务的项目中引入依赖

因为spring-cloud-starter-alibaba-seata会自动引入Seata的依赖，但是自动引入的依赖版本可能不是我们需要的，就可以同故宫exclusion排除掉，这里我们用Seata 0.9.0版本

<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-seata</artifactId>
    <exclusions>
        <exclusion>
            <groupId>io.seata</groupId>
            <artifactId>seata-all</artifactId>
        </exclusion>
    </exclusions>
</dependency>
<dependency>
    <groupId>io.seata</groupId>
    <artifactId>seata-all</artifactId>
    <version>0.9.0</version>
</dependency>

3.修改对应项目中修改SpringBoot配置文件

我们在SpringBoot的配置文将中添加如下配置：

spring:
  cloud:
    alibaba:
      seata:
        # 这里自定义的事务组名必须与seata-Server file.conf文件中配置的vgroup_mapping.xxx值一样
        tx-service-group: my_tx_group

4.将registry.conf和file.conf文件放到对应项目的resources目录下

实际上registry.conf和file.conf文件中多余的配置项可以删除，这里就放一个删除后的版本

registry.conf：

registry {
  # file 、nacos 、eureka、redis、zk、consul、etcd3、sofa
  type = "nacos"

  nacos {
    serverAddr = "localhost:8848"
    namespace = ""
    cluster = "default"
  }
}

config {
  # file、nacos 、apollo、zk、consul、etcd3
  type = "file"

  file {
    name = "file.conf"
  }
}

file.conf：这个file文件配置的vgroup_mapping.xxx就不与Seata Serve中的配置不同了，xxx必须是Seata Serve file.conf中配置的值，也就是my_tx_group

transport {
  # tcp udt unix-domain-socket
  type = "TCP"
  #NIO NATIVE
  server = "NIO"
  #enable heartbeat
  heartbeat = true
  #thread factory for netty
  thread-factory {
    boss-thread-prefix = "NettyBoss"
    worker-thread-prefix = "NettyServerNIOWorker"
    server-executor-thread-prefix = "NettyServerBizHandler"
    share-boss-worker = false
    client-selector-thread-prefix = "NettyClientSelector"
    client-selector-thread-size = 1
    client-worker-thread-prefix = "NettyClientWorkerThread"
    # netty boss thread size,will not be used for UDT
    boss-thread-size = 1
    #auto default pin or 8
    worker-thread-size = 8
  }
  shutdown {
    # when destroy server, wait seconds
    wait = 3
  }
  serialization = "seata"
  compressor = "none"
}
service {
  #vgroup->rgroup
  vgroup_mapping.my_tx_group = "default"
  #only support single node
  default.grouplist = "127.0.0.1:8091"
  #degrade current not support
  enableDegrade = false
  #disable
  disable = false
  #unit ms,s,m,h,d represents milliseconds, seconds, minutes, hours, days, default permanent
  max.commit.retry.timeout = "-1"
  max.rollback.retry.timeout = "-1"
}

client {
  async.commit.buffer.limit = 10000
  lock {
    retry.internal = 10
    retry.times = 30
  }
  report.retry.count = 5
  tm.commit.retry.count = 1
  tm.rollback.retry.count = 1
}

## transaction log store
store {
  ## store mode: file、db
  mode = "db"

  ## database store
  db {
    ## the implement of javax.sql.DataSource, such as DruidDataSource(druid)/BasicDataSource(dbcp) etc.
    datasource = "dbcp"
    ## mysql/oracle/h2/oceanbase etc.
    db-type = "mysql"
    driver-class-name = "com.mysql.jdbc.Driver"
    url = "jdbc:mysql://localhost:3306/seata"
    user = "root"
    password = "root"
    min-conn = 1
    max-conn = 3
    global.table = "global_table"
    branch.table = "branch_table"
    lock-table = "lock_table"
    query-limit = 100
  }
}
lock {
  ## the lock store mode: local、remote
  mode = "remote"

  remote {
    ## store locks in the seata's server
  }
}
recovery {
  #schedule committing retry period in milliseconds
  committing-retry-period = 1000
  #schedule asyn committing retry period in milliseconds
  asyn-committing-retry-period = 1000
  #schedule rollbacking retry period in milliseconds
  rollbacking-retry-period = 1000
  #schedule timeout retry period in milliseconds
  timeout-retry-period = 1000
}

transaction {
  undo.data.validation = true
  undo.log.serialization = "jackson"
  undo.log.save.days = 7
  #schedule delete expired undo_log in milliseconds
  undo.log.delete.period = 86400000
  undo.log.table = "undo_log"
}

## metrics settings
metrics {
  enabled = false
  registry-type = "compact"
  # multi exporters use comma divided
  exporter-list = "prometheus"
  exporter-prometheus-port = 9898
}

support {
  ## spring
  spring {
    # auto proxy the DataSource bean
    datasource.autoproxy = false
  }
}

5.在对应项目中配置Seata提供的代理数据源

package com.lynu.config;

import com.alibaba.druid.pool.DruidDataSource;
import io.seata.rm.datasource.DataSourceProxy;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
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;

import javax.sql.DataSource;

/**
 * 使用seata配置数据源DataSourceProxy以及mybatis的SqlSessionFactory
 * 需要在启动类排除调用spring默认的mybatis的自动配置DataSourceAutoConfiguration
 */
@Configuration
public class DataSourceProxyConfig {


    @Bean
    @ConfigurationProperties(prefix = "spring.datasource")
    public DataSource druidDataSource() {
        return new DruidDataSource();
    }


    @Primary
    @Bean("dataSource")
    public DataSourceProxy dataSourceProxy(DataSource druidDataSource) {
        return new DataSourceProxy(druidDataSource);
    }

    @Bean(name = "sqlSessionFactory")
    public SqlSessionFactory sqlSessionFactoryBean(DataSourceProxy dataSourceProxy) {
        SqlSessionFactoryBean bean = new SqlSessionFactoryBean();
        bean.setDataSource(dataSourceProxy);

        SqlSessionFactory factory;
        try {
            factory = bean.getObject();
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
        return factory;
    }

}

因为使用的Mybatis操作数据库，所以配置的就是SqlSessionFactory，其他的持久层框架与之类似，接下来需要我们将SpringBoot自带的数据源自动配置排除掉，因为我们需要使用自己的配置，在SpringBoot启动类上：

@SpringBootApplication(exclude = DataSourceAutoConfiguration.class)

6.在每一个涉及到分布式事务的数据库中添加undo_log表

undo_log表结构在conf/db_undo_log.sql

drop table `undo_log`;
CREATE TABLE `undo_log` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT,
  `branch_id` bigint(20) NOT NULL,
  `xid` varchar(100) NOT NULL,
  `context` varchar(128) NOT NULL,
  `rollback_info` longblob NOT NULL,
  `log_status` int(11) NOT NULL,
  `log_created` datetime NOT NULL,
  `log_modified` datetime NOT NULL,
  `ext` varchar(100) DEFAULT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `ux_undo_log` (`xid`,`branch_id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

接下来我们在需要开启分布式事务的Service方法上添加@GlobalTransactional注解即可

理论落地实现技术-TX-LCN

TX-LCN官网文档

TX-LCN比较适合在分布式微服务项目中使用，如SpringCloud，Dubbo

TX-LCN 主要有两个模块，Tx-Client(TC) Tx-Manager(TM). TC作为微服务下的依赖，TM是独立的服务，这里的TM，TC与Seata中的概念有些相反

版本说明：该框架作者正在开发6.0版本，而本次记录的是以5.0.2版本为准，TM下载地址

TX-LCN和SpringCloud整合

1.启动TM服务

TX-LCN的TM需要依赖MySQL+Redis，所以在下载目录txlcn-tm/src/main/resources/tx-manager.sql有建库建表语句

CREATE DATABASE IF NOT EXISTS  `tx-manager` DEFAULT CHARSET utf8 COLLATE utf8_general_ci;
USE `tx-manager`;

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

DROP TABLE IF EXISTS `t_tx_exception`;
CREATE TABLE `t_tx_exception`  (
  `id` bigint(20) NOT NULL AUTO_INCREMENT,
  `group_id` varchar(64) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
  `unit_id` varchar(32) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
  `mod_id` varchar(128) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
  `transaction_state` tinyint(4) NULL DEFAULT NULL,
  `registrar` tinyint(4) NULL DEFAULT NULL,
  `ex_state` tinyint(4) NULL DEFAULT NULL COMMENT '0 待处理 1已处理',
  `remark` varchar(10240) NULL DEFAULT NULL COMMENT '备注',
  `create_time` datetime(0) NULL DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 967 CHARACTER SET = utf8mb4 COLLATE = utf8mb4_general_ci ROW_FORMAT = Dynamic;

SET FOREIGN_KEY_CHECKS = 1;

修改配置信息(txlcn-tm/src/main/resources/application.properties)

spring.application.name=TransactionManager
server.port=7970
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/tx-manager?characterEncoding=UTF-8&useSSL=false
spring.datasource.username=root
spring.datasource.password=root
spring.jpa.database-platform=org.hibernate.dialect.MySQL5InnoDBDialect
spring.jpa.hibernate.ddl-auto=update

spring.redis.host=127.0.0.1
spring.redis.port=6379

修改pom.xml文件配置的plugins，注释掉配置的插件，添加SpringBoot-Maven插件

<build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <fork>true</fork>
                    <addResources>true</addResources>
                </configuration>
            </plugin>
        </plugins>
</build>

修改完这些文件之后就可以通过Maven构建了

mvn clean package -Dmaven.test.skip=true
java -jar target/txlcn-tm-5.0.2.RELEASE.jar

2.在每一个涉及到分布式事务的项目中引入依赖

<dependency>
    <groupId>com.codingapi.txlcn</groupId>
    <artifactId>txlcn-tc</artifactId>
    <version>5.0.2.RELEASE</version>
</dependency>
<dependency>
    <groupId>com.codingapi.txlcn</groupId>
    <artifactId>txlcn-txmsg-netty</artifactId>
    <version>5.0.2.RELEASE</version>
</dependency>

3.在对应项目开启分布式事务注解

在每一个涉及到分布式事务的微服务主类上使用@EnableDistributedTransaction

@SpringBootApplication
@EnableDistributedTransaction
public class DemoAApplication {
    public static void main(String[] args) {
        SpringApplication.run(DemoDubboClientApplication.class, args);
    }
}

接下来再在每一个涉及到分布式事务的业务方法配置@LcnTransaction，注意这里不同于Seata，只要涉及到分布式事务的每一个微服务中的业务方法上都需要添加@LcnTransaction注解。添加注解之后分布式事务就生效了

TX-LCN的默认TM的本机默认端口：127.0.0.1:8070，如果需要修改就在SpringBoot配置文件中修改：

tx-lcn:
  client:
    manager-address: 127.0.0.1:8070