分布式事物 Seata，AT模式

官方文档地址

1、Seata service下载地址：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。

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

    com.alibaba.cloud
    spring-cloud-alibaba-seata
    2.2.0.RELEASE
    
	
	    seata-spring-boot-starter
	    io.seata
	
    




    io.seata
    seata-spring-boot-starter
    1.2.0

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