seata基本使用
官方文檔：https://seata.io/zh-cn/docs/overview/what-is-seata.html
seata是一款開源的分布式事務解決方案，致力於在微服務架構下提供高性能和簡單易用的分布式事務服務
一ID+三組件模型
Transaction ID XID：全局唯一的事務ID
Transaction Coordinator（TC）：事務協調者，維護全局事務的運行狀態，負責協調並驅動全局事務的提交或回滾
Transaction Manager（TM）：事務管理器，定義全局事務的范圍：開始全局事務、提交或回滾全局事務
Resource Manager（RM）：資源管理器，控制分支事務，負責分支注冊、狀態匯報、並接收事務協調器的指令，驅動分支事務的提交和回滾
seata分布式事務處理過程
- TM向TC申請開啟一個全局事務，全局事務創建成功並生成一個全局唯一的XID
- XID在微服務調用鏈路的上下文中傳播
- RM向TC注冊分支事務，將其納入XID對應全局事務的管轄
- TM向TC發起針對XIK的全局提交或回滾決議
- TC調度XID下管轄的全部分支事務完成提交或回滾請求
windows安裝啟動seata服務端
下載seata，地址：https://github.com/seata/seata/releases
下載后解壓，不同版本的seata解壓后的內容不一樣，但配置都沒有太大的區別，筆者下載的是1.4.1版本
修改conf目錄下的file.conf配置文件
1、設置存儲模式為db
mode = "db"
2、設置db配置的用戶名和密碼（自己本地mysql的用戶名和密碼）
user = "root"
password = "123456"
注意：如果mysql版本是8.0及以上，driverClassName和url需要如下配置：
driverClassName = "com.mysql.cj.jdbc.Driver"
url = "jdbc:mysql://127.0.0.1:3306/seata?serverTimezone=UTC"
3、新建seata數據庫並執行對應sql腳本，conf目錄下的README-zh.md文件中server鏈接了server端的配置和sql，，為了方便，腳本內容貼在下面：
-- -------------------------------- 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(6),
`gmt_modified` DATETIME(6),
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`)
) 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 ('HandleAllSession', ' ', 0);
修改conf目錄下的registry.conf配置文件
4、設置注冊類型為nacos
type = "nacos"
5、設置服務注冊到nacos（namespace不指定默認為public）
registry {
# file 、nacos 、eureka、redis、zk、consul、etcd3、sofa
type = "nacos"
loadBalance = "RandomLoadBalance"
loadBalanceVirtualNodes = 10
nacos {
application = "seata-server"
serverAddr = "127.0.0.1:8848"
group = "SEATA_GROUP"
namespace = "426851b4-b7d3-4977-a440-bf6efa561760"
cluster = "default"
username = "nacos"
password = "nacos"
}
}
至此，配置完成，啟動nacos，然后雙擊bin目錄下的seata-server.bat啟動seata，可以在nacos看到seata服務成功注冊進去
registry.conf默認將配置存儲在file.conf，也可以設置存儲在nacos
實戰案例
業務背景
創建三個服務，一個訂單服務，一個庫存服務，一個賬戶服務
當用戶下單時，會在訂單服務中創建一個訂單，然后通過遠程調用庫存服務來扣減下單商品的庫存，再通過遠程調用賬戶服務來扣減用戶賬戶里面的余額，最后在訂單服務中修改訂單狀態為已完成
該操作跨越三個數據庫，有兩次遠程調用，很明顯會有分布式事務問題
數據庫
准備三個服務對應數據庫和表，sql腳本如下：
CREATE DATABASE seata_order;
USE seata_order;
CREATE TABLE t_order(
id BIGINT(11) NOT NULL AUTO_INCREMENT PRIMARY KEY ,
user_id BIGINT(11) DEFAULT NULL COMMENT '用戶id',
product_id BIGINT(11) DEFAULT NULL COMMENT '產品id',
count INT(11) DEFAULT NULL COMMENT '數量',
money DECIMAL(11,0) DEFAULT NULL COMMENT '金額',
status INT(1) DEFAULT NULL COMMENT '訂單狀態：0創建中，1已完結'
)ENGINE=InnoDB AUTO_INCREMENT=7 CHARSET=utf8;
CREATE DATABASE seata_storage;
USE seata_storage;
CREATE TABLE t_storage(
id BIGINT(11) NOT NULL AUTO_INCREMENT PRIMARY KEY ,
product_id BIGINT(11) DEFAULT NULL COMMENT '產品id',
total INT(11) DEFAULT NULL COMMENT '總庫存',
used INT(11) DEFAULT NULL COMMENT '已用庫存',
residue INT(11) DEFAULT NULL COMMENT '剩余庫存'
)ENGINE=InnoDB AUTO_INCREMENT=7 CHARSET=utf8;
INSERT INTO t_storage(id, product_id, total, used, residue) VALUES(1,1,100,0,100);
CREATE DATABASE seata_account;
USE seata_account;
CREATE TABLE t_account(
id BIGINT(11) NOT NULL AUTO_INCREMENT PRIMARY KEY ,
user_id BIGINT(11) DEFAULT NULL COMMENT '用戶id',
total DECIMAL(10,0) DEFAULT NULL COMMENT '總額度',
used DECIMAL(10,0) DEFAULT NULL COMMENT '已用額度',
residue DECIMAL(10,0) DEFAULT 0 COMMENT '剩余可用額度'
)ENGINE=InnoDB AUTO_INCREMENT=7 CHARSET=utf8;
INSERT INTO t_account(id, user_id, total, used, residue) VALUES(1,1,1000,0,1000);
每個數據庫需要分別創建一張seata回滾日志表，conf目錄下的README-zh.md文件中client 鏈接了該sql腳本（和舊版seata有所不同），為了方便，腳本內容貼在下面：
-- for AT mode you must to init this sql for you business database. the seata server not need it.
CREATE TABLE IF NOT EXISTS `undo_log`
(
`branch_id` BIGINT NOT NULL COMMENT 'branch transaction id',
`xid` VARCHAR(128) NOT NULL COMMENT 'global transaction id',
`context` VARCHAR(128) NOT NULL COMMENT 'undo_log context,such as serialization',
`rollback_info` LONGBLOB NOT NULL COMMENT 'rollback info',
`log_status` INT(11) NOT NULL COMMENT '0:normal status,1:defense status',
`log_created` DATETIME(6) NOT NULL COMMENT 'create datetime',
`log_modified` DATETIME(6) NOT NULL COMMENT 'modify datetime',
UNIQUE KEY `ux_undo_log` (`xid`, `branch_id`)
) ENGINE = InnoDB
AUTO_INCREMENT = 1
DEFAULT CHARSET = utf8mb4 COMMENT ='AT transaction mode undo table';
新建三個項目，分別對應訂單、庫存、賬戶，項目除了業務不同配置基本一致，由於業務代碼量太多（基本就是增刪改查比較簡單）所以下面只講解訂單項目相關配置：
導入依賴
spring-cloud-starter-alibaba-seata中包含了seata-all依賴，由於spring-cloud-starter-alibaba-seata版本可能跟本地安裝的seata版本不一致，所以需要排除spring-cloud-starter-alibaba-seata中的seata依賴，重新導入seata依賴保持版本和本地安裝的seata版本一致
<dependency>
<groupId>com.alibaba.cloud</groupId>
<artifactId>spring-cloud-starter-alibaba-seata</artifactId>
<exclusions>
<exclusion>
<artifactId>seata-all</artifactId>
<groupId>io.seata</groupId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>io.seata</groupId>
<artifactId>seata-all</artifactId>
<version>1.4.1</version>
</dependency>
seata客戶端配置
在項目resource文件夾下新建registry.conf配置文件，內容如下：
# 注冊管理
registry {
# 注冊類型:file 、nacos 、eureka、redis、zk、consul、etcd3、sofa
type = "nacos"
nacos {
application = "seata-server"
serverAddr = "127.0.0.1:8848"
group = "SEATA_GROUP"
namespace = "426851b4-b7d3-4977-a440-bf6efa561760"
cluster = "default"
username = "nacos"
password = "nacos"
}
}
# 配置管理
config {
# 配置信息存儲類型:file、nacos 、apollo、zk、consul、etcd3
type = "nacos"
nacos {
serverAddr = "127.0.0.1:8848"
namespace = ""
group = "SEATA_GROUP"
username = "nacos"
password = "nacos"
}
}
conf目錄下的README-zh.md文件中config-center鏈接了seata客戶端配置文件（config.txt）和讀取seata客戶端配置文件在nacos生成配置的腳本（nacos-confg-interactive.sh）
將config.txt和nacos-confg-interactive.sh下載到本地（config.txt需要放在nacos-confg-interactive.sh所在目錄的上一級目錄）
config.txt內容包含了seata服務端和客戶端所有配置，我們只需要保存客戶端相關配置即可，為了方便，內容貼在下面：
#For details about configuration items, see https://seata.io/zh-cn/docs/user/configurations.html
#Transport configuration, for client and server
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 事務組,default_tx_group可以自定義配置
service.vgroupMapping.default_tx_group=default
#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=false
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.rm.sqlParserType=druid
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
在nacos-confg-interactive.sh所在目錄啟動git終端執行以下命令運行腳本（本地需要先安裝git）
sh nacos-confg-interactive.sh
運行后根據提示在終端輸入nacos相關參數（和registry.conf配置保持一致）在nacos生成seata配置文件
application.yml配置文件seata相關配置
spring:
cloud:
alibaba:
seata:
# 配置事務組名稱
tx-service-group: default_tx_group
# 配置事務組值(service.vgroupMapping.default_tx_group中的default_tx_group是tx-service-group配置的值)
service:
vgroupMapping:
default_tx_group: default
注意：tx-service-group配置的值和config.txt中service.vgroupMapping配置保持一致
使用Seata對數據源進行代理
新建配置類
package com.yl.seata.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.transaction.SpringManagedTransactionFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import javax.sql.DataSource;
/**
* 使用Seata對數據源進行代理
*
* @auther Y-wee
*/
@Configuration
public class DataSourceProxyConfig {
@Value("${mybatis.mapperLocations}")
private String mapperLocations;
@Bean
@ConfigurationProperties(prefix = "spring.datasource")
public DataSource druidDataSource() {
return new DruidDataSource();
}
@Bean
public DataSourceProxy dataSourceProxy(DataSource dataSource) {
return new DataSourceProxy(dataSource);
}
@Bean
public SqlSessionFactory sqlSessionFactoryBean(DataSourceProxy dataSourceProxy) throws Exception {
SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
sqlSessionFactoryBean.setDataSource(dataSourceProxy);
sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources(mapperLocations));
sqlSessionFactoryBean.setTransactionFactory(new SpringManagedTransactionFactory());
return sqlSessionFactoryBean.getObject();
}
}
主啟動類
主動類取消數據源的自動創建
package com.yl.seata.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.openfeign.EnableFeignClients;
//@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
// 取消數據源的自動創建
@SpringBootApplication(exclude = DataSourceAutoConfiguration.class)
public class SeataOrderApplication {
public static void main(String[] args) {
SpringApplication.run(SeataOrderApplication.class,args);
}
}
業務層
業務方法加@GlobalTransactional注解實現事務控制
package com.yl.seata.order.service.impl;
import com.yl.seata.order.entity.Order;
import com.yl.seata.order.mapper.OrderMapper;
import com.yl.seata.order.service.AccountService;
import com.yl.seata.order.service.OrderService;
import com.yl.seata.order.service.StorageService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Service;
import io.seata.spring.annotation.GlobalTransactional;
import javax.annotation.Resource;
/**
* 訂單
*
* @auther Y-wee
*/
@Service
@Slf4j
public class OrderServiceImpl implements OrderService {
@Resource
private OrderMapper orderDao;
@Resource
private StorageService storageService;
@Resource
private AccountService accountService;
/**
* 創建訂單->調用庫存服務扣減庫存->調用賬戶服務扣減賬戶余額->修改訂單狀態
* 簡單說：下訂單->扣庫存->減余額->改狀態
*
* @param order
*/
@Override
@GlobalTransactional(rollbackFor = Exception.class)
public void create(Order order) {
log.info("-----開始新建訂單");
//1 新建訂單
orderDao.create(order);
//2 扣減庫存
log.info("-----訂單微服務開始調用庫存，做扣減Count");
storageService.decrease(order.getProductId(), order.getCount());
log.info("-----訂單微服務開始調用庫存，做扣減end");
//3 扣減賬戶
log.info("-----訂單微服務開始調用賬戶，做扣減Money");
accountService.decrease(order.getUserId(), order.getMoney());
log.info("-----訂單微服務開始調用賬戶，做扣減end");
//4 修改訂單狀態，從零到1,1代表已經完成
log.info("-----修改訂單狀態開始");
orderDao.update(order.getUserId(), 0);
log.info("-----修改訂單狀態結束");
log.info("-----下訂單結束了，O(∩_∩)O哈哈~");
}
}
配置完成->啟動nacos->啟動seata服務端->分別啟動訂單、庫存、賬戶項目->發送請求拋出異常事務回滾