（Java企业 / 公司项目）分布式事务Seata详解（含Seata+Nacos组合使用）（二）

比眉伴天荒 2024-04-29 19:05 36阅读 0赞

## 一. Seata Server配置Nacos ##

*  什么是配置中心?配置中心可以说是一个"大货仓",内部放置着各种配置文件,你可以通过自己所需进行获取配置加载到对应的客户端.比如Seata Client端(TM,RM),Seata Server(TC),会去读取全局事务开关,事务会话存储模式等信息.
 *  Seata的配置中心与Spring cloud的配置中心区别是?在广义上来说,并无区别,只不过Spring cloud的配置中心仅是作用于它们自身的组件,而Seata的配置中心也是一样是作用于Seata自身.(注:Spring cloud的配置中心与Seata无关)
 *  Seata支持哪些配置中心?
    
    1.  nacos
    2.  consul
    3.  apollo
    4.  etcd
    5.  zookeeper
    6.  file (读本地文件, 包含conf、properties、yml配置文件的支持)

配置nacos打开下载好的文件夹找到配置文件

![ccb45593a4c3450895a1885f6ee753f0.png][]

![ba9e8e84355b45ef8602126304417a78.png][]

config:
        # support: nacos, consul, apollo, zk, etcd3
        # type: file
        type: nacos
        nacos:
          server-addr: 127.0.0.1:8848
          namespace: train
          group: SEATA_GROUP
          username: nacos
          password: nacos
          context-path:
          ##if use MSE Nacos with auth, mutex with username/password attribute
          #access-key:
          #secret-key:
          data-id: seataServer.properties

配置中心的文件名就是data-id

接下来修改注册中心

![0ca8af4510c84e50af07c047f586b562.png][]

启动项目模块打开seata服务出现注册中心，接下来打开nacos查看命名空间，nacos的配置在前面的博客当中有可以查看怎么集成。

![4b30437e407c4021b9936e073c843caa.png][]

访问nacos，显示的信息都是前面配置成功的信息

![42735ed7b75b432a973d83fb131ce31f.png][]

注意这里的id需要和配置文件中的一致， group也需要一致![55ea6aaa3af146349743969fb45a3f80.png][]

下面的配置内容为

# 和微服务模块的seata.tx-service-group保持一致
     service.vgroupMapping.train-group=default
     service.default.grouplist=127.0.0.1:8091
    
     # 和微服务模块的seata.tx-service-group保持一致
     service.vgroupMapping.test-group=default1
     service.default1.grouplist=127.0.0.1:18091

AT模式会有一个全局锁，用于防止脏读，线程1的事务修改了库存，但还没提交事务，线程2读库存的时候，读的还是原来的库存

然后下面就是连接数据库nacos所要执行的，官方提供的MySQL数据表存全局id，分布式锁的表

![4ff3df98494248c28a3ab4eda1e28b4c.png][]

-- -------------------------------- 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`),
        KEY `idx_xid` (`xid`)
    ) 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);

现在所有的配置都放在nacos了。

## 二. Seata Client客户端配置nacos ##

在对应的模块下的配置文件 bootstrap.properties，下面的配置不用多说了

# seata注册中心，要和seata server的application.yml配置保持一致
    seata.registry.type=nacos
    seata.registry.nacos.application=seata-server
    seata.registry.nacos.server-addr=127.0.0.1:8848
    seata.registry.nacos.group=SEATA_GROUP
    seata.registry.nacos.namespace=train
    seata.registry.nacos.username=nacos
    seata.registry.nacos.password=nacos
    
    # seata配置中心，要和seata server的application.yml配置保持一致
    seata.config.type=nacos
    seata.config.nacos.server-addr=127.0.0.1:8848
    seata.config.nacos.group=SEATA_GROUP
    seata.config.nacos.namespace=train
    seata.config.nacos.dataId=seataServer.properties
    seata.config.nacos.username=nacos
    seata.config.nacos.password=nacos

![277033e2b1f4433e881fa9b7b0fd0975.png][]

使得当我们的接口出现错误，seata事务会进行回滚，全局事务会放进前面官方提供的表中， 其他的配置都可以简化

## 三. Seata和MySQL存储演示 ##

![7357c6b2fc394fa098a2c31ff6af9ce8.png][]

事务回滚逆向生成SQL数据

当我们把接口的线程延迟10秒后点击执行这个接口，我们会发现两个表里面有数据，在全局id表里面只有一个id，当我们10秒之后再次运行SQL刷新SQL之后就会被清除![21f4edc72b3c415fa11cef09df84d792.png][]

![1043d737f35a4aaeba86141eda373883.png][]

SQL限制官方

![da7ae83eeeeb49f4ab5d22bce4bef1eb.png][]

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