Python实现依赖注入的3种方法_依赖注入原理与实战

Python中实现依赖注入的方法

依赖注入(Dependency Injection, DI)是一种设计模式，用于解耦组件之间的依赖关系。在Python中，有几种实现依赖注入的方式：

1. 构造函数注入

class Service:
    def do_something(self):
        return "Service action"

class Client:
    def __init__(self, service):  # 通过构造函数注入依赖
        self.service = service
    
    def execute(self):
        return self.service.do_something()

# 使用
service = Service()
client = Client(service)  # 注入依赖
print(client.execute())

2. 方法注入

class Client:
    def set_service(self, service):  # 通过方法注入依赖
        self.service = service
    
    def execute(self):
        return self.service.do_something()

# 使用
client = Client()
client.set_service(Service())  # 注入依赖
print(client.execute())

3. 使用第三方库

injector库

from injector import inject, Injector, Module, provider

class Service:
    def do_something(self):
        return "Service action"

class Client:
    @inject
    def __init__(self, service: Service):
        self.service = service
    
    def execute(self):
        return self.service.do_something()

class AppModule(Module):
    @provider
    def provide_service(self) -> Service:
        return Service()

# 配置和使用
injector = Injector(AppModule())
client = injector.get(Client)
print(client.execute())

dependency-injector库

from dependency_injector import containers, providers

class Service:
    def do_something(self):
        return "Service action"

class Client:
    def __init__(self, service):
        self.service = service
    
    def execute(self):
        return self.service.do_something()

class Container(containers.DeclarativeContainer):
    service = providers.Singleton(Service)
    client = providers.Factory(Client, service=service)

# 使用
container = Container()
client = container.client()
print(client.execute())

4. 使用Python 3.7+的dataclasses

from dataclasses import dataclass

@dataclass
class Service:
    def do_something(self):
        return "Service action"

@dataclass
class Client:
    service: Service  # 依赖通过dataclass自动注入
    
    def execute(self):
        return self.service.do_something()

# 使用
client = Client(Service())  # 注入依赖
print(client.execute())

选择哪种方法取决于项目规模和复杂度。对于小型项目，手动依赖注入可能就足够了；对于大型项目，使用专门的DI库会更有利于管理依赖关系。