Go 报错 import cycle not allowed 怎么解决？循环依赖的三大修复方案与包分层规范

// service/order.go —— 业务层直接 import repository
import "example.com/demo/repository"

func CreateOrder() {
	repository.SaveOrder() // 依赖数据层
}

// repository/order.go —— 想回写状态，反向 import 了 service，形成环
import "example.com/demo/service"

// repository/store.go —— 接口定义在最底层，不依赖 service
package repository

type OrderStore interface {
	SaveOrder(id string, total float64) error
	MarkNotified(id string) error
}

// repository/memory.go —— 实现
type MemoryStore struct{ orders map[string]float64 }

func NewMemoryStore() *MemoryStore {
	return &MemoryStore{orders: make(map[string]float64)}
}

func (m *MemoryStore) SaveOrder(id string, total float64) error {
	m.orders[id] = total
	return nil
}

func (m *MemoryStore) MarkNotified(id string) error { return nil }

// service/order.go —— 只依赖接口，不依赖具体实现
package service

import "example.com/demo/repository"

type OrderService struct {
	store repository.OrderStore
}

func NewOrderService(s repository.OrderStore) *OrderService {
	return &OrderService{store: s}
}

func (svc *OrderService) Create(id string, total float64) error {
	if err := svc.store.SaveOrder(id, total); err != nil {
		return err
	}
	// 通知逻辑收敛在 service 内，repository 无需感知上层
	return svc.store.MarkNotified(id)
}

// main.go —— 在入口组装依赖
package main

import (
	"fmt"

	"example.com/demo/repository"
	"example.com/demo/service"
)

func main() {
	store := repository.NewMemoryStore()
	svc := service.NewOrderService(store)
	fmt.Println(svc.Create("order-1", 99.0))
}

// repository/order.go
package repository

var onSaved func(id string) // 由上层注入的回调

func SetOnSavedHook(fn func(id string)) { onSaved = fn }

func SaveOrder(id string, total float64) error {
	// ... 保存逻辑
	if onSaved != nil {
		onSaved(id) // 通知上层，但不 import 上层
	}
	return nil
}

// service/order.go —— 启动时注入回调
import "example.com/demo/repository"

func Init() {
	repository.SetOnSavedHook(func(id string) {
		fmt.Println("order saved:", id)
	})
}

# 列出每个包导入了哪些包，肉眼找环
go list -f '{{.ImportPath}} -> {{.Imports}}' ./...

# 只列出有问题的包链（编译失败时 go list 会直接报 cycle）
go list -e ./...