分布式事务seata的AT模式详解

橙子的随笔集

1358人浏览 · 2023-10-08 17:15:43

橙子的随笔集 · 2023-10-08 17:15:43 发布

一、seata简介

1、seata的官网

https://seata.io/zh-cn/docs/overview/terminology.htmlhttps://seata.io/zh-cn/docs/overview/terminology.html

首先，学习任何中间件我们先从官网看起，官网对各阶段模块都有详细的介绍，这里我们对seata做一个简单的介绍。

2、seata的各角色介绍

Seata 是一款开源的分布式事务解决方案，致力于提供高性能和简单易用的分布式事务服务。Seata 将为用户提供了 AT、TCC、SAGA 和 XA 事务模式，为用户打造一站式的分布式解决方案。这篇文章我们重点介绍AT模式的实现。

要了解Seata，首先我们要了解一下Seata的几个关键的概念：

- 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。

- TM (Transaction Manager) - 事务管理器（发起者，同时也是RM的一种）

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（每个参与事务的微服务）

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。

二、seata-server的下载和启动

1、seata-server的下载

使用seata处理分布式事务，我们必须下载seata-server作为TC的角色，来协调全局事务的处理，本文章使用的是1.5.2版本的seata-server,大家注意版本的选择，尽量和文章保持一致，不然可能会有和其他依赖版本不一致的问题。

官方下载地址:https://github.com/seata/seata/releases

进入下载页面选择v1.5.2版本,下载到本地

2、seata-server的配置文件修改

下载后解压到本地，进入\seata\conf\application.yml,修改文件中的配置项，主要配置seata的配置中心和注册中心的参数信息，具体配置参数如下

#seata的服务端口
server:
  port: 7091

#seata的应用服务名称
spring:
  application:
    name: seata-server

#console的参数，必须配置，不配置的话启动参数解析会报错，我理解这是1.5.0版本的一个bug
console: 
  user:
    username:
    password:

#seata的配置中心参数，这里选择的nacos的配置方式
seata:
  config:
    # support: nacos, consul, apollo, zk, etcd3
    type: nacos
    nacos:
      server-addr: 127.0.0.1:8848
      group: SEATA_GROUP
      namespace: seata
      username: nacos
      password: nacos
      data-id: seataServer.properties

#seata的注册中心的配置参数，这里选择的是nacos的配置中心
  registry:
    # support: nacos, eureka, redis, zk, consul, etcd3, sofa
    type: nacos
    nacos:
      application: seata-server
      server-addr: 127.0.0.1:8848
      group: SEATA_GROUP
      namespace:
      cluster: default
      username: nacos
      password: nacos
#  server:
#    service-port: 8091 #If not configured, the default is '${server.port} + 1000'
  security:
    secretKey: SeataSecretKey0c382ef121d778043159209298fd40bf3850a017
    tokenValidityInMilliseconds: 1800000
    ignore:
      urls: /,/**/*.css,/**/*.js,/**/*.html,/**/*.map,/**/*.svg,/**/*.png,/**/*.ico,/console-fe/public/**,/api/v1/auth/login

3、application.yml中配置中心和注册中心参数详解

配置中心参数解释

seata:
  config:
    # support: nacos, consul, apollo, zk, etcd3
    type: nacos #选择的配置中心类型为nacos
    nacos:
      server-addr: 127.0.0.1:8848 #配置中心的地址
      group: SEATA_GROUP          #配置中心的分组
      namespace: seata            #配置中心使用的命名空间
      username: nacos                
      password: nacos
      data-id: seataServer.properties#配置中心中的数据ID

注册中心参数解释

registry:
    # support: nacos, eureka, redis, zk, consul, etcd3, sofa
    type: nacos                    #注册中心类型
    nacos:
      application: seata-server    #应用名称
      server-addr: 127.0.0.1:8848  #注册中心地址
      group: SEATA_GROUP           #注册中心的分组名称
      namespace:                   #注册中心的命名空间
      cluster: default             #注册中心的集群配置,和配置中心dataID下面
                                  service.vgroupMapping.mygroup的参数保持一致
      username: nacos
      password: nacos

讲道理，配置完上面的这些参数seata-server的配置就完成了，可以启动，但是因为依赖nacos，所以需要把下面的nacos配置启动完成之后再启动seata-server.

三、nacos的下载和启动

1、nacos的官网地址

官网网址：https://nacos.io/zh-cn/index.html

Nacos = **注册中心+配置中心组合**

2、naocs的下载地址

这里下载的是nacos的2.1.0版本，搭配上面1.5.2版本的seata-server

Releases · alibaba/nacos · GitHuban easy-to-use dynamic service discovery, configuration and service management platform for building cloud native applications. - Releases · alibaba/nacoshttps://github.com/alibaba/nacos/releases

3、启动nacos

下载之后解压到本地，进入\nacos-server-2.1.0\bin直接启动，如下图,在cmd模式下，输入指令

./startup.cmd -m standalone

启动成功之后访问地址localhost:8848/nacos,账号密码都是nacos,一下页面为正常启动后访问页面

四、nacos配置中心dataID配置

1、创建命名空间seata

根据步骤二seata-server中配置文件中配置中心的参数，在nacos的配置文件中创建命名空间seata

2、配置nacos配置参数

然后在配置列表的seata命名空间中创建第二步骤中的dataID为seataServer.properties的配置参数

3、seataServer.properties配置参数详解

transport.type=TCP
transport.server=NIO
transport.heartbeat=true
transport.enableTmClientBatchSendRequest=false
transport.enableRmClientBatchSendRequest=true
transport.enableTcServerBatchSendResponse=false
transport.rpcRmRequestTimeout=30000
transport.rpcTmRequestTimeout=30000
transport.rpcTcRequestTimeout=30000
transport.threadFactory.bossThreadPrefix=NettyBoss
transport.threadFactory.workerThreadPrefix=NettyServerNIOWorker
transport.threadFactory.serverExecutorThreadPrefix=NettyServerBizHandler
transport.threadFactory.shareBossWorker=false
transport.threadFactory.clientSelectorThreadPrefix=NettyClientSelector
transport.threadFactory.clientSelectorThreadSize=1
transport.threadFactory.clientWorkerThreadPrefix=NettyClientWorkerThread
transport.threadFactory.bossThreadSize=1
transport.threadFactory.workerThreadSize=default
transport.shutdown.wait=3
transport.serialization=seata
transport.compressor=none

#Transaction routing rules configuration, only for the client
service.vgroupMapping.mygroup=default
#If you use a registry, you can ignore it
service.default.grouplist=127.0.0.1:8091
service.enableDegrade=false
service.disableGlobalTransaction=false

#Transaction rule configuration, only for the client
client.rm.asyncCommitBufferLimit=10000
client.rm.lock.retryInterval=10
client.rm.lock.retryTimes=30
client.rm.lock.retryPolicyBranchRollbackOnConflict=true
client.rm.reportRetryCount=5
client.rm.tableMetaCheckEnable=true
client.rm.tableMetaCheckerInterval=60000
client.rm.sqlParserType=druid
client.rm.reportSuccessEnable=false
client.rm.sagaBranchRegisterEnable=false
client.rm.sagaJsonParser=fastjson
client.rm.tccActionInterceptorOrder=-2147482648
client.tm.commitRetryCount=5
client.tm.rollbackRetryCount=5
client.tm.defaultGlobalTransactionTimeout=60000
client.tm.degradeCheck=false
client.tm.degradeCheckAllowTimes=10
client.tm.degradeCheckPeriod=2000
client.tm.interceptorOrder=-2147482648
client.undo.dataValidation=true
client.undo.logSerialization=jackson
client.undo.onlyCareUpdateColumns=true
server.undo.logSaveDays=7
server.undo.logDeletePeriod=86400000
client.undo.logTable=undo_log
client.undo.compress.enable=true
client.undo.compress.type=zip
client.undo.compress.threshold=64k
#For TCC transaction mode
tcc.fence.logTableName=tcc_fence_log
tcc.fence.cleanPeriod=1h

#Log rule configuration, for client and server
log.exceptionRate=100

#Transaction storage configuration, only for the server. The file, DB, and redis configuration values are optional.
store.mode=db
store.lock.mode=db
store.session.mode=db
#Used for password encryption

#If `store.mode,store.lock.mode,store.session.mode` are not equal to `file`, you can remove the configuration block.
store.file.dir=file_store/data
store.file.maxBranchSessionSize=16384
store.file.maxGlobalSessionSize=512
store.file.fileWriteBufferCacheSize=16384
store.file.flushDiskMode=async
store.file.sessionReloadReadSize=100

#seata的数据表配置
store.db.datasource=druid
store.db.dbType=mysql
store.db.driverClassName=com.mysql.cj.jdbc.Driver
store.db.url=jdbc:mysql://127.0.0.1:3306/seata?useUnicode=true&rewriteBatchedStatements=true
store.db.user=root
store.db.password=root
store.db.minConn=5
store.db.maxConn=30
store.db.globalTable=global_table
store.db.branchTable=branch_table
store.db.distributedLockTable=distributed_lock
store.db.queryLimit=100
store.db.lockTable=lock_table
store.db.maxWait=5000

#These configurations are required if the `store mode` is `redis`. If `store.mode,store.lock.mode,store.session.mode` are not equal to `redis`, you can remove the configuration block.
store.redis.mode=single
store.redis.single.host=127.0.0.1
store.redis.single.port=6379
store.redis.maxConn=10
store.redis.minConn=1
store.redis.maxTotal=100
store.redis.database=0
store.redis.queryLimit=100

#Transaction rule configuration, only for the server
server.recovery.committingRetryPeriod=1000
server.recovery.asynCommittingRetryPeriod=1000
server.recovery.rollbackingRetryPeriod=1000
server.recovery.timeoutRetryPeriod=1000
server.maxCommitRetryTimeout=-1
server.maxRollbackRetryTimeout=-1
server.rollbackRetryTimeoutUnlockEnable=false
server.distributedLockExpireTime=10000
server.xaerNotaRetryTimeout=60000
server.session.branchAsyncQueueSize=5000
server.session.enableBranchAsyncRemove=false
server.enableParallelRequestHandle=false

#Metrics configuration, only for the server
metrics.enabled=false
metrics.registryType=compact
metrics.exporterList=prometheus
metrics.exporterPrometheusPort=9898

4、创建seata-server使用的数据表

seata-server做为TC事务协调者，在分布式事务的处理过程中，需要用到四个数据表global_table(全局事务记录表)、branch_table(分支事务记录表)、lock_table(全局锁表)、distributed_lock(分布式锁)，具体的数据表脚本如下：

这几个表的数据库链接信息配置在上面seataServer.properties中，如下:

#seata的数据表配置
store.db.datasource=druid
store.db.dbType=mysql
store.db.driverClassName=com.mysql.cj.jdbc.Driver
store.db.url=jdbc:mysql://127.0.0.1:3306/seata?useUnicode=true&rewriteBatchedStatements=true
store.db.user=root
store.db.password=root
store.db.minConn=5
store.db.maxConn=30
store.db.globalTable=global_table
store.db.branchTable=branch_table
store.db.distributedLockTable=distributed_lock
store.db.queryLimit=100
store.db.lockTable=lock_table
store.db.maxWait=5000

-- -------------------------------- The script used when storeMode is 'db' --------------------------------
-- the table to store GlobalSession data
CREATE TABLE IF NOT EXISTS `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_status_gmt_modified` (`status` , `gmt_modified`),
    KEY `idx_transaction_id` (`transaction_id`)
) ENGINE = InnoDB
  DEFAULT CHARSET = utf8mb4;

-- the table to store BranchSession data
CREATE TABLE IF NOT EXISTS `branch_table`
(
    `branch_id`         BIGINT       NOT NULL,
    `xid`               VARCHAR(128) NOT NULL,
    `transaction_id`    BIGINT,
    `resource_group_id` VARCHAR(32),
    `resource_id`       VARCHAR(256),
    `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`)
) ENGINE = InnoDB
  DEFAULT CHARSET = utf8mb4;

-- the table to store lock data
CREATE TABLE IF NOT EXISTS `lock_table`
(
    `row_key`        VARCHAR(128) NOT NULL,
    `xid`            VARCHAR(128),
    `transaction_id` BIGINT,
    `branch_id`      BIGINT       NOT NULL,
    `resource_id`    VARCHAR(256),
    `table_name`     VARCHAR(32),
    `pk`             VARCHAR(36),
    `status`         TINYINT      NOT NULL DEFAULT '0' COMMENT '0:locked ,1:rollbacking',
    `gmt_create`     DATETIME,
    `gmt_modified`   DATETIME,
    PRIMARY KEY (`row_key`),
    KEY `idx_status` (`status`),
    KEY `idx_branch_id` (`branch_id`),
    KEY `idx_xid_and_branch_id` (`xid` , `branch_id`)
) ENGINE = InnoDB
  DEFAULT CHARSET = utf8mb4;

CREATE TABLE IF NOT EXISTS `distributed_lock`
(
    `lock_key`       CHAR(20) NOT NULL,
    `lock_value`     VARCHAR(20) NOT NULL,
    `expire`         BIGINT,
    primary key (`lock_key`)
) ENGINE = InnoDB
  DEFAULT CHARSET = utf8mb4;

INSERT INTO `distributed_lock` (lock_key, lock_value, expire) VALUES ('AsyncCommitting', ' ', 0);
INSERT INTO `distributed_lock` (lock_key, lock_value, expire) VALUES ('RetryCommitting', ' ', 0);
INSERT INTO `distributed_lock` (lock_key, lock_value, expire) VALUES ('RetryRollbacking', ' ', 0);
INSERT INTO `distributed_lock` (lock_key, lock_value, expire) VALUES ('TxTimeoutCheck', ' ', 0);

五、seata-server的启动

以上涉及seata-server依赖nacos的注册中心启动和配置中心配置之后,就可以启动seata-server了，进入\seata\bin，直接点击seata-server.bat启动seata-server

seata启动完成之后，进入nacos观察服务列表，可以看到seata-server已经做为一个服务注册上来了

到这里，seata-server依赖nacos做为注册中心和配置中心的搭建已经完成，下面我们编写业务代码模块来验证seata实现分布式事务处理的能力。

六、分布式业务模块的搭建

1、业务场景

这里我们创建两个功能模块，订单模块seata-order和库存模块seata-stock,编写业务代码，让订单模块去调用库存模块，先减少库存，然后创建订单，如果订单创建失败，所有分支事务的数据都回滚。这里订单模块做为TM事务的管理者(发起者)、订单模块和库存模块具体的业务操作做为RM实现分支事务的注册和处理。(为了演示方便，这里只涉及订单和库存两个模块)

2、业务表结构

这里涉及两个功能模块，seata-order订单工程和seata-stock库存工程，这两个功能分别用独立的数据库test_order(order表和undo_log表)和 test_stock(stock表和undo_log表)

DROP TABLE IF EXISTS `order`;
CREATE TABLE `order` (
  `product` varchar(255) NOT NULL,
  `count` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;



-- ----------------------------
-- Table structure for stock
-- ----------------------------
DROP TABLE IF EXISTS `stock`;
CREATE TABLE `stock` (
  `product` varchar(255) DEFAULT NULL,
  `count` int(11) DEFAULT NULL,
  `money` int(255) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;


-- ----------------------------
-- Table structure for undo_log
-- ----------------------------
DROP TABLE IF EXISTS `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 DEFAULT CHARSET=utf8;

3、搭建业务项目

主项目

主项目的pom依赖：注意这里spring-cloud-alibaba采用的版本是2.2.9-release

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.12.RELEASE</version>
        <relativePath/>
    </parent>
    <groupId>com.czing</groupId>
    <artifactId>springnacos</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springnacos</name>
    <packaging>pom</packaging>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
            <version>2.2.7.RELEASE</version>
        </dependency>
    </dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-alibaba-dependencies</artifactId>
                <version>2.2.9.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <modules>
        <module>seata-order</module>
        <module>seata-stock</module>
    </modules>

</project>

seata-order模块的代码搭建

pom文件:

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>com.czing</groupId>
        <artifactId>springnacos</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.czing</groupId>
    <artifactId>seata-order</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>seata-order</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
            <version>2.2.5.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-seata</artifactId>
        </dependency>
        <dependency>
            <groupId>io.seata</groupId>
            <artifactId>seata-spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.2.17</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.3.5</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

application.yml的配置文件

server:
  port: 8888
spring:
  application:
    name: seata-order-8888
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848
        group: SEATA_GROUP
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    druid:
      url: jdbc:mysql://localhost:3306/test_order?useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai
      driver-class-name: com.mysql.cj.jdbc.Driver
      username: root
      password: root
service-url:
  nacos-user-service: http://seata-stock-8777
seata:
  application-id: ${spring.application.name}
  # seata 服务分组，要与服务端seataServer.properties配置service.vgroup_mapping的后缀对应
  tx-service-group: mygroup
  registry:
    # 指定nacos作为注册中心
    type: nacos
    nacos:
      application: seata-server
      server-addr: 127.0.0.1:8848
      namespace:
      group: SEATA_GROUP

  config:
    # 指定nacos作为配置中心
    type: nacos
    nacos:
      server-addr: 127.0.0.1:8848
      namespace: seata
      group: SEATA_GROUP
      data-id: seataServer.properties

代码结构截图和具体业务代码

config层下面的MybatisConfig类实现数据源的代理，重要！！！数据源只有被代理才能实现分支事务的注册和回滚，因为这个问题我排查了两天，诸位注意。

package com.czing.order.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.mybatis.spring.annotation.MapperScan;
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 org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.core.io.support.ResourcePatternResolver;

import javax.sql.DataSource;

/**
 *
 * 需要用到分布式事务的微服务都需要使用seata DataSourceProxy代理自己的数据源
 */
@Configuration
@MapperScan("com.czing.order.mapper")
public class MybatisConfig {
    
    /**
     * 从配置文件获取属性构造datasource，注意前缀，这里用的是druid，根据自己情况配置,
     * 原生datasource前缀取"spring.datasource"
     *
     * @return
     */
    @Bean
    @ConfigurationProperties(prefix = "spring.datasource.druid")
    public DruidDataSource druidDataSource() {
        DruidDataSource druidDataSource = new DruidDataSource();
        return druidDataSource;
    }
    
    /**
     * 构造datasource代理对象，替换原来的datasource
     * @param druidDataSource
     * @return
     */
    @Primary
    @Bean("dataSource")
    public DataSource dataSourceProxy(DruidDataSource druidDataSource) {
//        return new DataSourceProxyXA(druidDataSource);
        return new DataSourceProxy(druidDataSource);
    }
    
    
    @Bean(name = "sqlSessionFactory")
    public SqlSessionFactory sqlSessionFactoryBean(DataSource dataSource) throws Exception {
        SqlSessionFactoryBean factoryBean = new SqlSessionFactoryBean();
        //设置代理数据源
        factoryBean.setDataSource(dataSource);
        ResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
        factoryBean.setMapperLocations(resolver.getResources("classpath*:mybatis/**/*-mapper.xml"));
        
        org.apache.ibatis.session.Configuration configuration=new org.apache.ibatis.session.Configuration();
        //使用jdbc的getGeneratedKeys获取数据库自增主键值
        configuration.setUseGeneratedKeys(true);
        //使用列别名替换列名
        configuration.setUseColumnLabel(true);
        //自动使用驼峰命名属性映射字段，如userId ---> user_id
        configuration.setMapUnderscoreToCamelCase(true);
        factoryBean.setConfiguration(configuration);
        
        return factoryBean.getObject();
    }
    
}

client层的StockClient类，为了通过restTemplate远程调用stock模块，这里也可以采用feign的方式调用

package com.czing.order.client;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;

/**
 * @Description TODO
 * @Author wangchengzhi
 * @Date 2023/9/24 21:43
 */
@Service
public class StockClient {
    @Value("${service-url.nacos-user-service}")
    private String serviceUrl;

    @Autowired
    private RestTemplate restTemplate;

   public String decr(){
       ResponseEntity<String> result = restTemplate.getForEntity(serviceUrl+"/stockInfo/decr",String.class);
       return result.getBody();
   }
}

controller入口层

package com.czing.order.controller;

import com.czing.order.client.StockClient;
import com.czing.order.service.OrderInfoService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * @Description TODO
 * @Author wangchengzhi
 * @Date 2023/9/24 15:06
 */
@RestController
@RequestMapping(value = "/orderInfo")

public class OrderInfo {

    @Autowired
    private StockClient stockClient;
    @Autowired
    private OrderInfoService orderInfoService;

    /**
     * @Author wangchengzhi
     * @Description创建订单
     * @Date 15:30 2023/9/24
     * @Param
     * @return
     **/
    @GetMapping(value = "/create")

    public String create(){
        //创建订单
        String s = orderInfoService.creatOrder();

        return s;
    }
}

service层的接口和其实现类

package com.czing.order.service;



/**
 * @Author wangchengzhi
 * @Description 订单的相关操作
 * @Date 15:28 2023/9/24
 * @Param
 * @return
 **/
public interface OrderInfoService {
    String creatOrder();
}

package com.czing.order.service.impl;

import com.czing.order.client.StockClient;
import com.czing.order.mapper.OrderMapper;
import com.czing.order.service.OrderInfoService;
import io.seata.spring.annotation.GlobalTransactional;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;


/**
 * @Description TODO
 * @Author wangchengzhi
 * @Date 2023/9/24 15:14
 */
@Service
public class OrderInfoServiceImpl implements OrderInfoService {

    @Autowired
    private StockClient stockClient;
    @Autowired
    private OrderMapper orderMapper;
    @GlobalTransactional
    @Override
    public String creatOrder() {

        //减少库存
        String decr = stockClient.decr();
        int i = 1/0;

        boolean order = orderMapper.createOrder();
        if(order){
            return "创建订单成功";
        }else{
            return "订单创建失败";
        }

    }
}

数据处理层mapper下面的OrderMapper

package com.czing.order.mapper;


import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Mapper;
import org.springframework.stereotype.Component;


@Component
@Mapper
public interface OrderMapper {
   @Insert("INSERT INTO order (`product`, `count`) VALUES ('老北京','6')")
   boolean createOrder();

}

order工程的启动类

package com.czing.order;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication(exclude = DataSourceAutoConfiguration.class)
@EnableDiscoveryClient
public class SeataOrderApplication {

    public static void main(String[] args) {
        SpringApplication.run(SeataOrderApplication.class, args);
    }

    @Bean
    @LoadBalanced
    public RestTemplate getRestTemplate(){
        return new RestTemplate();
    }

}

seata-stock模块的代码搭建

pom文件

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>com.czing</groupId>
        <artifactId>springnacos</artifactId>
        <version>0.0.1-SNAPSHOT</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.czing</groupId>
    <artifactId>seata-stock</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>seata-stock</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.2.17</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.3.5</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-seata</artifactId>
        </dependency>
        <dependency>
            <groupId>io.seata</groupId>
            <artifactId>seata-spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

config下面的MybatisConfig实现数据源代理类

package com.czing.stock.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.mybatis.spring.annotation.MapperScan;
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 org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.core.io.support.ResourcePatternResolver;

import javax.sql.DataSource;

/**
 *
 * 需要用到分布式事务的微服务都需要使用seata DataSourceProxy代理自己的数据源
 */
@Configuration
@MapperScan("com.czing.stock.mapper")
public class MybatisConfig {
    
    /**
     * 从配置文件获取属性构造datasource，注意前缀，这里用的是druid，根据自己情况配置,
     * 原生datasource前缀取"spring.datasource"
     *
     * @return
     */
    @Bean
    @ConfigurationProperties(prefix = "spring.datasource.druid")
    public DruidDataSource druidDataSource() {
        DruidDataSource druidDataSource = new DruidDataSource();
        return druidDataSource;
    }
    
    /**
     * 构造datasource代理对象，替换原来的datasource
     * @param druidDataSource
     * @return
     */
    @Primary
    @Bean("dataSource")
    public DataSource dataSourceProxy(DruidDataSource druidDataSource) {
//        return new DataSourceProxyXA(druidDataSource);
        return new DataSourceProxy(druidDataSource);
    }
    
    
    @Bean(name = "sqlSessionFactory")
    public SqlSessionFactory sqlSessionFactoryBean(DataSource dataSource) throws Exception {
        SqlSessionFactoryBean factoryBean = new SqlSessionFactoryBean();
        //设置代理数据源
        factoryBean.setDataSource(dataSource);
        ResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
        factoryBean.setMapperLocations(resolver.getResources("classpath*:mybatis/**/*-mapper.xml"));
        
        org.apache.ibatis.session.Configuration configuration=new org.apache.ibatis.session.Configuration();
        //使用jdbc的getGeneratedKeys获取数据库自增主键值
        configuration.setUseGeneratedKeys(true);
        //使用列别名替换列名
        configuration.setUseColumnLabel(true);
        //自动使用驼峰命名属性映射字段，如userId ---> user_id
        configuration.setMapUnderscoreToCamelCase(true);
        factoryBean.setConfiguration(configuration);
        
        return factoryBean.getObject();
    }
    
}

controller入口类

package com.czing.stock.controller;

import com.czing.stock.service.impl.StockInfoService;
import io.seata.core.context.RootContext;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * @Description TODO
 * @Author wangchengzhi
 * @Date 2023/9/24 15:12
 */
@RestController
@RequestMapping(value = "/stockInfo")
public class StockController {
    private Logger logger = LoggerFactory.getLogger(this.getClass());
    @Autowired
    StockInfoService stockInfoService;
    @RequestMapping(value = "/decr")
    public String decr(){
        logger.info("当前 XID: {}", RootContext.getXID());
        return stockInfoService.decr();
    }
}

service层的接口和实现类

package com.czing.stock.service.impl;

/**
 * @Author wangchengzhi
 * @Description 库存相关的操作
 * @Date 15:15 2023/9/24
 * @Param
 * @return
 **/

public interface StockInfoService {
    //减少库存
    String  decr();
}

package com.czing.stock.service.impl;

import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import com.czing.stock.mapper.StockMapper;
/**
 * @Description 库存相关操作的实现类
 * @Author wangchengzhi
 * @Date 2023/9/24 15:14
 */
@Service
public class StockInfoServiceImpl implements StockInfoService {

    @Resource
    private StockMapper stockMapper;
    @Override
    public String decr() {
        stockMapper.decr();
        return "我是库存管理者，你进来啦";
    }
}

mapper层的StockMapper类

package com.czing.stock.mapper;

import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Update;

@Mapper
public interface StockMapper {

    @Update("update stock set count = count-1 where product='老北京' ")
    boolean decr();
}

启动类

package com.czing.stock;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;

@SpringBootApplication(exclude = DataSourceAutoConfiguration.class)
@EnableDiscoveryClient
public class SeataStockApplication {

    public static void main(String[] args) {
        SpringApplication.run(SeataStockApplication.class, args);
    }

}

七、分布式事务的异常回滚验证

1、启动seata-order和seata-stock项目

nacos的服务列表注册情况

2、调用seata-order的入口

调用地址:localhost:8888/orderInfo/create

seata-order创建订单的具体逻辑

@Service
public class OrderInfoServiceImpl implements OrderInfoService {

    @Autowired
    private StockClient stockClient;
    @Autowired
    private OrderMapper orderMapper;
    @GlobalTransactional
    @Override
    public String creatOrder() {

        //减少库存
        String decr = stockClient.decr();

        //为了让事务报错，验证数据回滚的场景
        int i = 1/0;

        //创建订单
        boolean order = orderMapper.createOrder();
        if(order){
            return "创建订单成功";
        }else{
            return "订单创建失败";
        }

    }
}

启动之后seata的TM和RM注册成功的截图

3、事务注册回滚的流程

调用localhost:8888/orderInfo/create的时候增加@GlobalTransactional注解开启全局事务，调用进来的时候把全局事务的xid写入global_table表

执行String decr = stockClient.decr()减少库存之后，开启分支事务记录到branch_table表，并开启分支事务的表锁记录到lock_table表。

调用库存之后分支事务会存数据到test_stock库的undo_log表中，如果事务发生异常则进行回滚，并删除undo_log。整体的流程图如下图所示。

八、注意事项总结

1、注意spring cloud alibaba、nacos、seata-server依赖版本

2、加载数据源代理

这是AT模式的核心，只有使用了代理数据源才能实现分支事务的注册和回滚，不然不能实现分支事务的分布式处理。

以上为seata的AT模式详解，分享给大家，如有疑问，欢迎评论区留言讨论。

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