分布式事物 Seata，AT模式

女爷i 2021-07-24 23:46 485阅读 0赞

[官方文档地址][Link 1]

1、Seata service下载地址：[https://github.com/seata/seata/releases][https_github.com_seata_seata_releases]

2、下载完之后解压。

3、conf目录下自定义配置

seata—>conf—>file.conf

## transaction log store, only used in seata-server
    store {
      ## store mode: file、db
    ##改成db
      mode = "db"
    
      ## file store property
      file {
        ## store location dir
        dir = "sessionStore"
        # branch session size , if exceeded first try compress lockkey, still exceeded throws exceptions
        maxBranchSessionSize = 16384
        # globe session size , if exceeded throws exceptions
        maxGlobalSessionSize = 512
        # file buffer size , if exceeded allocate new buffer
        fileWriteBufferCacheSize = 16384
        # when recover batch read size
        sessionReloadReadSize = 100
        # async, sync
        flushDiskMode = async
      }
    
      ## database store property
      db {
        ## the implement of javax.sql.DataSource, such as DruidDataSource(druid)/BasicDataSource(dbcp) etc.
        datasource = "druid"
        ## mysql/oracle/postgresql/h2/oceanbase etc.
        dbType = "mysql"
        driverClassName = "com.mysql.jdbc.Driver"
    
    ## 如果要是没有seata数据库，要建立一个
        url = "jdbc:mysql://172.0.0.1:3306/seata?useUnicode=true&characterEncoding=UTF-8"
        user = "123"
        password = "123"
        minConn = 5
        maxConn = 30
    
    ## 建好数据库之后新建下面的这三张表
        globalTable = "global_table"
        branchTable = "branch_table"
        lockTable = "lock_table"
        queryLimit = 100
        maxWait = 5000
      }
    }

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_gmt_modified_status` (`gmt_modified`, `status`),
        KEY `idx_transaction_id` (`transaction_id`)
    ) ENGINE = InnoDB
      DEFAULT CHARSET = utf8;
    
    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 = utf8;
    
    
    CREATE TABLE IF NOT EXISTS `lock_table`
    (
        `row_key`        VARCHAR(128) NOT NULL,
        `xid`            VARCHAR(96),
        `transaction_id` BIGINT,
        `branch_id`      BIGINT       NOT NULL,
        `resource_id`    VARCHAR(256),
        `table_name`     VARCHAR(32),
        `pk`             VARCHAR(36),
        `gmt_create`     DATETIME,
        `gmt_modified`   DATETIME,
        PRIMARY KEY (`row_key`),
        KEY `idx_branch_id` (`branch_id`)
    ) ENGINE = InnoDB
      DEFAULT CHARSET = utf8;

seata—>conf—>registry.conf     这里用的是nacos

registry {
      # file 、nacos 、eureka、redis、zk、consul、etcd3、sofa
      type = "nacos"
    
      nacos {
        application = "seata-server-chenmf"
        serverAddr = "172.0.0.1:8848"
        namespace = "ffa677cd-a2e5-4af6-bf32-102fc1397d33"
        cluster = "default"
        username = ""
        password = ""
      }
    }
    
    config {
      # file、nacos 、apollo、zk、consul、etcd3
      type = "nacos"
    
      nacos {
        serverAddr = "172.0.0.1:8848"
        namespace = "ffa677cd-a2e5-4af6-bf32-102fc1397d33"
        group = "DEFAULT_GROUP"
        username = ""
        password = ""
      }
    }

4、进入seata-server解压之后的bin文件夹,双击seata-server.bat启动。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzI4MjU2Nzgz_size_16_color_FFFFFF_t_70][]

5、配置、导包（每个微服务都要加）

# 这里配置的是微服务之间的调用超时时间
    feign:
      client:
        config:
          default:
            connect-timeout: 4000
            read-timeout: 4000
    
    # Seata 配置项，对应 SeataProperties 类
    seata:
      application-id: ${spring.application.name} # Seata 应用编号，默认为 ${spring.application.name}
      tx-service-group: seata-crm-group # Seata 事务组编号，用于 TC 集群名，此处的名称一定要与 vgroup-mapping下配置的参数保持一致
      # Seata 服务配置项，对应 ServiceProperties 类
      service:
        # 虚拟组和分组的映射
        vgroup_mapping:
          seata-crm-group: default
      # Seata 注册中心配置项，对应 RegistryProperties 类
      registry:
        type: nacos # 注册中心类型，默认为 file
        nacos:
          cluster: DEFAULT_GROUP # 使用的 Seata 分组
          namespace: ffa677cd-a2e5-4af6-bf32-102fc1397d33 # Nacos 命名空间
          serverAddr: 172.0.0.1:8848 # Nacos 服务地址
          application: seata-server-chenmf

<dependency>
        <groupId>com.alibaba.cloud</groupId>
        <artifactId>spring-cloud-alibaba-seata</artifactId>
        <version>2.2.0.RELEASE</version>
        <exclusions>
    	<exclusion>
    	    <artifactId>seata-spring-boot-starter</artifactId>
    	    <groupId>io.seata</groupId>
    	</exclusion>
        </exclusions>
    </dependency>
    
    
    <dependency>
        <groupId>io.seata</groupId>
        <artifactId>seata-spring-boot-starter</artifactId>
        <version>1.2.0</version>
    </dependency>

6、在每个微服务下面建立一张undo\_log表

CREATE TABLE IF NOT EXISTS `undo_log`
    (
        `id`            BIGINT(20)   NOT NULL AUTO_INCREMENT COMMENT 'increment id',
        `branch_id`     BIGINT(20)   NOT NULL COMMENT 'branch transaction id',
        `xid`           VARCHAR(100) 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     NOT NULL COMMENT 'create datetime',
        `log_modified`  DATETIME     NOT NULL COMMENT 'modify datetime',
        PRIMARY KEY (`id`),
        UNIQUE KEY `ux_undo_log` (`xid`, `branch_id`)
    ) ENGINE = InnoDB
      AUTO_INCREMENT = 1
      DEFAULT CHARSET = utf8 COMMENT ='AT transaction mode undo table';

7、在微服务业务上加入@GlobalTransactional注解

A服务调B服务saveUser()方法并插入数据

@GlobalTransactional(rollbackFor = Exception.class)
    @PostMapping(value = "saveclient")
    public Integer save(@RequestBody User user){
            User one = new User();
            one.setId(4432);
            testTransactionService.saveUser(one);
            // 手动抛出异常
            int a = 1/0;
            userService.save(user);
            return user.getId();
    }

8、测试，通过微服务A调用微服务B中的saveUser()事务方法，执行完毕，返回微服务A之后，手动抛出异常，看B事务是否已经回滚

9、在B执行完毕之后，返回微服务A，抛出异常之前debug，查看库里的user表和undo\_log表里面数据的变化

[Link 1]: https://seata.io/zh-cn/docs/overview/what-is-seata.html
[https_github.com_seata_seata_releases]: https://github.com/seata/seata/releases
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