分布式事务 Seata 详解 + 链路追踪 SkyWalking 实战

一、事务基础概念

1.1 什么是本地事务

当需要一次执行多条 SQL 时，要么全部成功提交，要么全部失败回滚 ，这就是事务。经典总结：去不了终点，回到原点。

1.2 事务四大特性（ACID）

原子性（Atomicity）：事务是最小执行单位，不可分割
一致性（Consistency）：事务执行前后数据保持正确
隔离性（Isolation）：并发事务相互隔离，互不干扰
持久性（Durability）：事务提交后不可回滚

1.3 本地事务控制方式

1）数据库原生控制

mysql

复制代码

START TRANSACTION;
-- 保存订单
-- 扣减库存
COMMIT;
-- 异常执行
ROLLBACK;

2）JDBC 控制事务

java

复制代码

// 关闭自动提交
conn.setAutoCommit(false);
try {
    // 执行多条SQL
    conn.commit();
} catch (Exception e) {
    conn.rollback();
}

3）Spring AOP 事务

java

复制代码

@Transactional
public void insertOrder(TbOrder tbOrder) {
    // 保存订单
    tbOrderMapper.insertSelective(tbOrder);
    // 扣减库存
    itemServiceFeign.updateItem(tbOrder.getItemId(), tbOrder.getNum());
}

二、分布式事务详解

2.1 什么是分布式事务

单体应用拆分为微服务后，跨服务、跨数据库、跨 JVM 完成的事务操作，就是分布式事务。典型场景：下单 + 减库存、注册送积分、跨库转账。

2.2 分布式事务产生场景

微服务远程调用 （跨 JVM）：订单服务 → 商品服务
单服务访问多数据库 ：操作不同 MySQL 实例
多服务访问同数据库 ：不同连接导致事务失效

2.3 本地事务失效问题

java

复制代码

@Transactional
public void insertOrder(TbOrder tbOrder) {
    // 保存订单
    tbOrderMapper.insertSelective(tbOrder);
    // 远程扣减库存
    itemServiceFeign.updateItem(...);
    // 模拟异常
    int a = 6/0;
}

两个服务中订单回滚了
库存扣减无法回滚，出现数据不一致

三、分布式事务解决方案 ------ Seata

3.1 Seata 简介

Seata（原 Fescar）是阿里巴巴开源的一站式分布式事务解决方案 ，目标：让分布式事务用起来像本地事务一样简单。官网：https://seata.io/zh-cn/https://seata.io/zh-cn/

3.2 Seata 四种事务模式

XA 模式：强一致性，无业务侵入
AT 模式 ：最终一致，无侵入，默认使用
TCC 模式：最终一致，有业务侵入
SAGA 模式：长事务，有业务侵入

3.3 Seata 三大核心组件

TC（Transaction Coordinator）：事务协调器，维护全局事务状态，协调提交 / 回滚
TM（Transaction Manager）：事务管理器，定义全局事务，开启 / 提交 / 回滚全局事务
RM（Resource Manager）：资源管理器，管理本地事务，注册分支、上报状态

四、Seata AT 模式工作流程

4.1 一阶段（执行 + 准备回滚）

解析 SQL，获取表、条件等信息
查询前镜像（修改前数据）
执行业务 SQL
查询后镜像（修改后数据）
写入undo_log回滚日志
注册分支事务，申请全局锁
本地事务提交
上报状态给 TC

4.2 二阶段 - 回滚

接收 TC 回滚指令
根据 XID + BranchID 查询undo_log
数据校验
使用前镜像恢复数据
本地提交，删除undo_log

4.3 二阶段 - 提交

全局事务成功，异步删除 undo_log，速度极快。

五、Seata 安装与启动（Nacos 注册配置）

5.1 下载

https://github.com/seata/seata/releases

5.2 上传并解压

复制代码

cd /usr/upload
tar -zxvf seata-server-1.4.2.tar.gz -C /usr/local

5.3 修改 registry.conf

修改seata/seata-server-1.4.2/conf/目录下的registry.conf文件：

properties

复制代码


registry {
  type = "nacos"
  nacos {
    serverAddr = "192.168.19.132:8848"    # nacos的地址
    group = "SEATA_GROUP"                 # seata服务所在分组
    application = "seata-server"      # seata服务所在的名称空间，这里不填就是使用默认的"public"
    cluster = "default"               # TC集群名，默认是"default"
  }
}
config {
  type = "nacos"
  nacos {
    serverAddr = "192.168.19.132:8848"
    group = "SEATA_GROUP"
    dataId = "seataServer.properties"
  }
}

5.4 Nacos 配置中心添加配置

配置文件地址：https://gitee.com/seata-io/seata/raw/develop/script/config-center/config.txt主要配置：存储模式为 db，连接 MySQL。

复制代码

# 数据存储方式，db代表数据库
store.mode=db
store.db.datasource=druid
store.db.dbType=mysql
store.db.driverClassName=com.mysql.jdbc.Driver
store.db.url=jdbc:mysql://192.168.19.130:3306/seata?useUnicode=true&rewriteBatchedStatements=true&useSSL=false
store.db.user=root
store.db.password=1111
store.db.minConn=5
store.db.maxConn=30
store.db.globalTable=global_table
store.db.branchTable=branch_table
store.db.queryLimit=100
store.db.lockTable=lock_table
store.db.maxWait=5000
# 事务、日志等配置
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.undo.logSaveDays=7
server.undo.logDeletePeriod=86400000
# 客户端与服务端传输方式
transport.serialization=seata
transport.compressor=none
# 关闭metrics功能，提高性能
metrics.enabled=false
metrics.registryType=compact
metrics.exporterList=prometheus
metrics.exporterPrometheusPort=9898

效果：

5.5 创建 Seata 服务表

mysql

复制代码

-- global_table、branch_table、lock_table

建表语句：https://gitee.com/seata-io/seata/raw/develop/script/server/db/mysql.sql

sql 复制代码

-- -------------- 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_gmt_modified_status` (`gmt_modified`, `status`),
    KEY `idx_transaction_id` (`transaction_id`)
) ENGINE = InnoDB
  DEFAULT CHARSET = utf8;

-- 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 = utf8;

-- the table to store lock data
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;

5.6 启动 Seata

sql 复制代码

cd seata/bin
./seata-server.sh -h 192.168.19.133 -p 8091

注册成功如下：

六、微服务整合 Seata 实战

6.1 准备数据库

item 库：tb_item + undo_log
order 库：tb_order + undo_log

tb_item 建表语句

mysql

sql 复制代码

-- 商品表 ----------------------------
DROP TABLE IF EXISTS `tb_item`;
CREATE TABLE `tb_item` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) DEFAULT NULL,
  `num` int(11) DEFAULT '0',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8;
-- Records of tb_item ----------------------------
INSERT INTO `tb_item` VALUES ('1', '手机', '100');
INSERT INTO `tb_item` VALUES ('3', '电脑', '100');

-- 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 = utf8 COMMENT ='AT transaction mode undo table';

tb_order 建表语句

mysql

sql 复制代码

-- Table structure for tb_order ----------------------------
DROP TABLE IF EXISTS `tb_order`;
CREATE TABLE `tb_order` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `item_id` int(11) DEFAULT NULL,
  `num` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

-- 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 = utf8 COMMENT ='AT transaction mode undo table';

6.2 项目结构

springcloud_parent（父工程）

pom.xml

java 复制代码

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.hg</groupId>
    <artifactId>springcloud_parent</artifactId>
    <packaging>pom</packaging>
    <version>1.0-SNAPSHOT</version>
    <modules>
        <module>springcloud_common</module>
        <module>nacos_provider</module>
        <module>nacos_consumer</module>
        <module>nacos_config</module>
        <module>ribbon_provider_01</module>
        <module>ribbon_provider_02</module>
        <module>ribbon_consumer</module>
        <module>feign_provider_01</module>
        <module>feign_provider_02</module>
        <module>feign_interface</module>
        <module>feign_consumer</module>
        <module>sentinel_provider</module>
        <module>sentinel_interface</module>
        <module>sentinel_consumer</module>
        <module>api_gateway</module>
        <module>seata_item_service</module>
        <module>seata_common</module>
        <module>seata_order_service</module>
        <module>seata_Item_service_feign</module>
    </modules>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>

    <dependencyManagement>
        <dependencies>
            <!--Spring Boot-->
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>2.3.2.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <!--spring cloud Netflix-->
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Hoxton.SR9</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <!--spring cloud 阿里巴巴-->
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-alibaba-dependencies</artifactId>
                <version>2.2.6.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
</project>

common_pojo（实体）

Item 实体

java 复制代码

package com.hg.pojo;

public class Item {
    private Integer id;
    private String name;
    private Integer num;

    public Item() {
    }

    @Override
    public String toString() {
        return "Item{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", num=" + num +
                '}';
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getNum() {
        return num;
    }

    public void setNum(Integer num) {
        this.num = num;
    }
}

Order 实体

java 复制代码

package com.hg.pojo;

public class Order {
    private Integer id;
    private Integer itemId;
    private Integer num;



    @Override
    public String toString() {
        return "Order{" +
                "id=" + id +
                ", itemId=" + itemId +
                ", num=" + num +
                '}';
    }

    public Order() {
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public Integer getItemId() {
        return itemId;
    }

    public void setItemId(Integer itemId) {
        this.itemId = itemId;
    }

    public Integer getNum() {
        return num;
    }

    public void setNum(Integer num) {
        this.num = num;
    }
}

seata_item_service（商品服务）

pom.xml

java 复制代码

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>seata_demo</artifactId>
        <groupId>com.hg</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>seata_item_service</artifactId>

    <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>
        <!-- MyBatis -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
        </dependency>
        <!-- MySql Driver -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <!--Alibaba DataBase Connection Pool-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
        </dependency>
        <!--MyBatis And Spring Integration Starter-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>com.hg</groupId>
            <artifactId>common_pojo</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
    </dependencies>
</project>

application.yml

java 复制代码

server:
  port: 81
spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://192.168.19.130:3306/item?characterEncoding=UTF-8&serverTimezone=Asia/Shanghai
    username: root
    password: 1111
    type: com.alibaba.druid.pool.DruidDataSource
  cloud:
    nacos:
      discovery:
        server-addr: 192.168.19.132:8848
  application:
    name: seata-item-service
mybatis:
  mapper-locations: classpath:mapper/*.xml
seata:
  registry:
    type: nacos #查找TC服务，参考registry.conf
    nacos:
      server-addr: 192.168.19.132:8848
      namespace: ""
      group: SEATA_GROUP
      application: seata-server #TC服务名
  tx-service-group: springcloud-parent #事务组，根据tx-service-group名称获得TC服务cluster名称
  service:
    vgroup-mapping: #tx-service-group与TC cluster的映射关系
      springcloud-parent: default

service

java 复制代码

@Service
@Transactional
public class ItemServiceImpl implements ItemService {
    @Autowired
    private ItemMapper itemMapper;
    @Override
    public void updateItem(Integer itemId, Integer num) {
        Item tbItem = itemMapper.selectByPrimaryKey(itemId);
        tbItem.setNum(tbItem.getNum()-num);
        itemMapper.updateByPrimaryKeySelective(tbItem);
    }
}

controller

java 复制代码

@RestController
@RequestMapping("/item")
public class ItemController {
    @Autowired
    private ItemService itemService;

    @RequestMapping("/updateItem")
    public void updateItem(Integer itemId, Integer num){
        itemService.updateItem(itemId,num);
    }
}

mapper

java 复制代码

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.hg.mapper.ItemMapper">

    <!-- 商品表结果映射 -->
    <resultMap id="BaseResultMap" type="com.hg.pojo.Item">
        <id column="id" property="id" jdbcType="INTEGER"/>
        <result column="name" property="name" jdbcType="VARCHAR"/>
        <result column="num" property="num" jdbcType="INTEGER"/>
    </resultMap>

    <!-- 根据主键查询商品信息 -->
    <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Integer">
        SELECT id, name, num
        FROM tb_item
        WHERE id = #{id,jdbcType=INTEGER}
    </select>

    <!-- 根据主键选择性更新商品信息 -->
    <update id="updateByPrimaryKeySelective" parameterType="com.hg.pojo.Item">
        UPDATE tb_item
        <set>
            <if test="name != null">
                name = #{name,jdbcType=VARCHAR},
            </if>
            <if test="num != null">
                num = #{num,jdbcType=INTEGER},
            </if>
        </set>
        WHERE id = #{id,jdbcType=INTEGER}
    </update>

</mapper>

app启动类

java 复制代码

@SpringBootApplication
@EnableDiscoveryClient
@MapperScan("com.hg.mapper")
public class seataItemServiceApp {
    public static void main(String[] args) {
        SpringApplication.run(seataItemServiceApp.class);
    }
}

seata_item_feign（feign 接口）

pom.xml

java 复制代码

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>springcloud_parent</artifactId>
        <groupId>com.hg</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>seata_Item_service_feign</artifactId>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>
        <dependency>
            <groupId>com.hg</groupId>
            <artifactId>seata_common</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
    </dependencies>
</project>

Feign接口

java 复制代码

@FeignClient("seata-item-service")
@RequestMapping("/item")
public interface SeataItemFeign {
    @RequestMapping("/updateItem")
    public void updateItem(@RequestParam("itemId") Integer itemId, @RequestParam("num") Integer num);
}

seata_order_service（订单服务）

pom.xml

java 复制代码

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>springcloud_parent</artifactId>
        <groupId>com.hg</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>seata_order_service</artifactId>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </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.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.1</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.0</version>
        </dependency>
        <dependency>
            <groupId>com.hg</groupId>
            <artifactId>seata_common</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
        <dependency>
            <groupId>com.hg</groupId>
            <artifactId>seata_Item_service_feign</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-seata</artifactId>
        </dependency>
    </dependencies>
</project>

application.yml

java 复制代码

server:
  port: 80
spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://192.168.19.130:3306/order?characterEncoding=UTF-8&serverTimezone=Asia/Shanghai
    username: root
    password: 1111
    type: com.alibaba.druid.pool.DruidDataSource
  cloud:
    nacos:
      discovery:
        server-addr: 192.168.19.132:8848
  application:
    name: seata-order-service

mybatis:
  mapper-locations: classpath:mapper/*.xml
  type-aliases-package: com.hg.pojo
seata:
  registry:
    type: nacos #查找TC服务，参考registry.conf
    nacos:
      server-addr: 192.168.19.132:8848
      namespace: ""
      group: SEATA_GROUP
      application: seata-server #TC服务名
  tx-service-group: springcloud-parent #事务组，根据tx-service-group名称获得TC服务cluster名称
  service:
    vgroup-mapping: #tx-service-group与TC cluster的映射关系
      springcloud-parent: default

controller

java 复制代码

@RestController
@RequestMapping("/order")
public class OrderController {
    @Autowired
    private OrderService orderService;

    @RequestMapping("/addOrder")
    public Map addOrder(Order order){
        Map<Integer, Object> result = new HashMap<>();
        try {
            orderService.addOrder(order);
            result.put(200,"下单成功");
            return result;
        } catch (Exception e) {
            e.printStackTrace();
            result.put(500,"下单失败");
            return result;
        }
    }
}

service

java 复制代码

@Service
@Transactional
public class OrderServiceImpl implements OrderService {
    @Autowired
    private OrderMapper orderMapper;
    @Autowired
    private SeataItemFeign seataItemFeign;
    @Override
    public void addOrder(Order order) {
        //1、保存订单
        orderMapper.addOrder(order);
        //2、扣减库存
        seataItemFeign.updateItem(order.getItemId(), order.getNum());
        //模拟扣款失败，此时扣减库存会回滚吗？
        int a = 6/0;
    }
}

mapper

java 复制代码

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.hg.mapper.OrderMapper">

    <!-- 订单表结果映射 -->
    <resultMap id="BaseResultMap" type="com.hg.pojo.Order">
        <id column="id" property="id" jdbcType="INTEGER"/>
        <result column="item_id" property="itemId" jdbcType="INTEGER"/>
        <result column="num" property="num" jdbcType="INTEGER"/>
    </resultMap>

    <!-- 添加订单 -->
    <insert id="addOrder" parameterType="com.hg.pojo.Order" useGeneratedKeys="true" keyProperty="id">
        INSERT INTO tb_order (item_id, num)
        VALUES (#{itemId}, #{num})
    </insert>

</mapper>

app启动类

java 复制代码

@SpringBootApplication
@EnableDiscoveryClient
@EnableFeignClients
@MapperScan("com.hg.mapper")
public class seataOrderServiceApp {
    public static void main(String[] args) {
        SpringApplication.run(seataOrderServiceApp.class);
    }
}

6.3 核心依赖

xml

复制代码

<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-seata</artifactId>
</dependency>

6.4 微服务配置（application.yml）

查找TC服务，需要四个信息：namespace、group、application name、cluster name

yaml

item服务和order服务都需要配置

java 复制代码

seata:
  registry:
    type: nacos
    nacos:
      server-addr: 192.168.19.132:8848
      group: SEATA_GROUP
      application: seata-server
  tx-service-group: springcloud-parent
  service:
    vgroup-mapping:
      springcloud-parent: default

测试：

启动seata_item_service服务如果发现RM注册失败

查看注册到Nacos中的seata-server服务ip不是公网

在seata启动时，后面加上-h:ip

java 复制代码

./seata-server.sh -h 192.168.204.135

6.5 开启分布式事务

在订单服务 方法上添加 @GlobalTransactional

java

复制代码

@Service
public class OrderServiceImpl implements OrderService {
    @GlobalTransactional
    public void insertOrder(TbOrder tbOrder) {
        // 保存订单
        tbOrderMapper.insertSelective(tbOrder);
        // 扣减库存
        itemServiceFeign.updateItem(...);
        // 模拟异常
        int a = 6/0;
    }
}

6.6 测试效果

异常时：订单回滚 + 库存回滚
成功时：订单创建 + 库存扣减完美解决分布式事务一致性问题！

七、分布式链路追踪 ------ SkyWalking

7.1 为什么需要 SkyWalking

微服务调用链复杂，一个请求跨多个服务，传统日志无法追踪整条链路，SkyWalking 可以：

分布式链路追踪
服务性能监控
异常告警
日志采集

7.2 SkyWalking 架构

Agent：探针，无侵入采集数据
OAP：接收、分析、存储数据
UI：可视化展示

7.3 SkyWalking 安装

下载：https://archive.apache.org/dist/skywalking/
解压（路径不能有中文）
修改 UI 端口：webapp/application.yml

yaml

复制代码

serverPort: ${SW_SERVER_PORT:-18080} #端口号

启动：bin/startup.bat

启动成功后会启动两个服务，skywalking-aop-server和skywalking-web-ui

skywalking-aop-server服务启动后会暴露11800和12800两个端口，分别为收集监控数据的端口11800和接受前端请求的端口12800

访问：http://localhost:18080

八、SkyWalking 接入微服务

8.1 JVM 探针配置

yaml

复制代码

# 你的 skywalking-agent.jar包地址
-javaagent:D:\skywalking-agent\skywalking-agent.jar
# 在skywalking上显示的服务名
-DSW_AGENT_NAME=skywalking-agent
#你的skywalking-aop-server地址及端口号
-DSW_AGENT_COLLECTOR_BACKEND_SERVICES=127.0.0.1:11800

注意：配置时去掉注释

启动成功后，随便对一个接口进行访问，然后刷新我们的skywalking UI界面

服务界面介绍

8.2 数据持久化（MySQL）

默认使用 H2 内存库，重启数据丢失，改为 MySQL：

修改 config/application.yml
放入 MySQL 驱动到 oap-libs
创建数据库swtest ，重启自动建表

九、SkyWalking 高级功能

9.1 自定义链路追踪（@Trace）

xml

复制代码

<dependency>
    <groupId>org.apache.skywalking</groupId>
    <artifactId>apm-toolkit-trace</artifactId>
    <version>8.5.0</version>
</dependency>

java

复制代码

@Trace
@Tags({
    @Tag(key = "参数", value = "arg[0]"),
    @Tag(key = "返回值", value = "returnedObj")
})
public String test(String str) {
    return "hello " + str;
}

为追踪链路增加其额外的信息，实现方式：在方法上增加@Tags和@Tag

测试

重启后，对一个接口访问，然后刷新skywalking UI界面，自定义链路追踪效果：

可以看到我们的业务方法也进入到了链路当中

链路追踪添加的额外信息，效果：

9.2 日志整合

引入日志依赖，配置 logback.xml，日志自动带上 TraceID。

在需要添加日志的服务里引入依赖

java 复制代码

<!--apm‐toolkit‐logback‐1.x  日志 -->
<dependency>
    <groupId>org.apache.skywalking</groupId>
    <artifactId>apm-toolkit-logback-1.x</artifactId>
    <version>8.5.0</version>
</dependency>

添加文件logback.xml

java 复制代码

<?xml version="1.0" encoding="UTF-8"?>
<configuration>

    <!-- 日志输出格式 -->
    <property name="log.pattern"
              value="%black(%contextName-) %red(%d{yyyy-MM-dd HH:mm:ss}) %green([%thread]) %boldMagenta([%tid]) %highlight(%-5level) %boldMagenta(%logger{36}) - %gray(%msg%n)"/>

    <!-- 控制台输出 -->
    <appender name="console" class="ch.qos.logback.core.ConsoleAppender">
        <encoder class="ch.qos.logback.core.encoder.LayoutWrappingEncoder">
            <layout class="org.apache.skywalking.apm.toolkit.log.logback.v1.x.TraceIdPatternLogbackLayout">
                <Pattern>${log.pattern}</Pattern>
            </layout>
        </encoder>
    </appender>
    <!-- 使用gRpc将日志发送到skywalking服务端 -->
    <appender name="grpc-log" class="org.apache.skywalking.apm.toolkit.log.logback.v1.x.log.GRPCLogClientAppender">
        <encoder class="ch.qos.logback.core.encoder.LayoutWrappingEncoder">
            <layout class="org.apache.skywalking.apm.toolkit.log.logback.v1.x.TraceIdPatternLogbackLayout">
                <Pattern>${log.pattern}</Pattern>
            </layout>
        </encoder>
    </appender>

    <root level="info">
        <appender-ref ref="console"/>
        <appender-ref ref="grpc-log"/>
    </root>
</configuration>

重启项目，查看日志

9.3 性能分析

针对接口做慢查询采样，定位性能瓶颈。

模拟慢查询

java 复制代码

@RequestMapping(value = "/getUserById/{id}")
public User getUserById(@PathVariable Integer id) {
    try {
        Thread.sleep(500);
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
    System.out.println("测试慢查询");
    return userFeign.getUserById(id);
}

点击新建任务

设置监控端点

请求5次以上然后进行刷新

作用：可以准确定位资源的问题所在

9.4 告警配置

修改 config/alarm-settings.yml，配置阈值与 Webhook，实现服务异常自动通知。

实体类用来接受数据

java 复制代码

@Data
public class SkAlarmDTO {
    private Integer scopeId;
    private String scope;
    private String name;
    private String id0;
    private String id1;
    private String ruleName;
    private String alarmMessage;
    private Long startTime;
 }

实现告警通知

java 复制代码

@RestController
@RequestMapping("/skAlarm")
public class SkAlarmController {

    @RequestMapping("/getMsg")
    public void getMsg(@RequestBody List<SkAlarmDTO> skAlarmDTOList){
        System.out.println("接收消息，然后进行处理-发送短信，发送邮件");
        StringBuilder sb = new StringBuilder();
        for (SkAlarmDTO dto : skAlarmDTOList) {
            sb.append("\nscopeId: ").append(dto.getScopeId())
                    .append("\nscope: ").append(dto.getScope())
                    .append("\n目标 Scope 的实体名称: ").append(dto.getName())
                    .append("\nScope 实体的 ID: ").append(dto.getId0())
                    .append("\nid1: ").append(dto.getId1())
                    .append("\n告警规则名称: ").append(dto.getRuleName())
                    .append("\n告警消息内容: ").append(dto.getAlarmMessage())
                    .append("\n告警时间: ").append(dto.getStartTime())
                    .append("\n‐‐‐‐‐‐‐‐‐‐‐‐‐‐--------------------------‐\n");
        }
        System.out.println(sb);
    }
}

添加告警后需要请求的接口

修改config/alarm-settings.yml文件

java 复制代码

webhooks:
  - http://127.0.0.1:80/skAlarm/getMsg

定义报错的接口

java 复制代码

@RequestMapping(value = "/getUserById/{id}")
public User getUserById(@PathVariable Integer id) {
    int a = 6/0;
    return userFeign.getUserById(id);
}

重新启动skywalking，然后对接口进行请求触发告警，控制台即可打印出告警信息

十、总结

本地事务：单库单服务，@Transactional 即可
分布式事务：跨服务 / 跨库，必须用 Seata
Seata AT 模式：无侵入、最终一致，生产首选
SkyWalking：无侵入链路追踪 + 性能监控 + 告警，微服务必备

本文从理论到实战，完整覆盖分布式事务与链路追踪两大微服务核心痛点，建议收藏反复练习！