为什么我们需要依赖注入：
Most important, for me, is making it easy to follow the Single Responsibility Principle.
DI/IoC makes it simple for me to manage dependencies between objects.
In turn, that makes it easier for me to break coherent functionality off into it's
own contract (interface).
As a result, my code has been far more modularized since I learned of DI/IoC.
Another result of this is that I can much more easily see my way through to a
design that supports the Open-Closed Principle. This is one of the most confidence
inspiring techniques (second only to automated testing). I doubt I could espouse the
virtues of Open-Closed Principle enough.
DI/IoC is one of the few things in my programming career that has been a "game changer."
There is a huge gap in quality between code I wrote before & after learning DI/IoC.
Let me emphasize that some more. HUGE improvement in code quality.
go get github.com/douyacun/go-ioc
构造一个问候服务需要知道
- 向谁问候
- 问候什么
package simple
import (
"fmt"
di "github.com/douyacun/go-ioc"
"testing"
)
type MessagePrinter interface {
Print()
}
type UserProvider interface {
GetUserName() string
}
type UserProviderImpl struct {
UserName string `di:"userName"` // will match message
}
func (impl *UserProviderImpl) GetUserName() string {
return impl.UserName
}
type MessagePrinterImpl struct {
message string `di:"message"` // will match message
}
func (impl *MessagePrinterImpl) Print() {
fmt.Println(impl.message)
}
func (impl *MessagePrinterImpl) SetMessage(m string) {
impl.message = m
}
type GreeterService struct {
UserProvider UserProvider `di:"*"` // will match type
Printer MessagePrinter `di:"*"` // will match type
}
func (s *GreeterService) Print() {
fmt.Printf("%s:", s.UserProvider.GetUserName())
s.Printer.Print()
}通常来说的初始化过程
message := "say hello"
printer := &MessagePrinterImpl{}
printer.SetMessage(message)
userName := "word"
userProvider := &UserProviderImpl{UserName: userName}
service := &MessagePrinterService{Printer: printer, UserProvider:userProvider}
service.Print()
使用依赖注入后
di.Register("message", "hello world")
di.Register("userName", "douyacun")
di.Register("printer", &MessagePrinterImpl{})
di.Register("userProvider", &UserProviderImpl{})
service := &GreeterService{}
di.MustBind(service)
service.Print()