中介者模式

中介者模式封装对象之间互交，使依赖变的简单，并且使复杂互交简单化，封装在中介者中。

例子中的中介者使用单例模式生成中介者。

中介者的change使用switch判断类型。

mediator.go

package mediatorimport ("fmt""strings"
)type CDDriver struct {Data string
}func (c *CDDriver) ReadData() {c.Data = "music,image"fmt.Printf("CDDriver: reading data %s\n", c.Data)GetMediatorInstance().changed(c)
}type CPU struct {Video stringSound string
}func (c *CPU) Process(data string) {sp := strings.Split(data, ",")c.Sound = sp[0]c.Video = sp[1]fmt.Printf("CPU: split data with Sound %s, Video %s\n", c.Sound, c.Video)GetMediatorInstance().changed(c)
}type VideoCard struct {Data string
}func (v *VideoCard) Display(data string) {v.Data = datafmt.Printf("VideoCard: display %s\n", v.Data)GetMediatorInstance().changed(v)
}type SoundCard struct {Data string
}func (s *SoundCard) Play(data string) {s.Data = datafmt.Printf("SoundCard: play %s\n", s.Data)GetMediatorInstance().changed(s)
}type Mediator struct {CD    *CDDriverCPU   *CPUVideo *VideoCardSound *SoundCard
}var mediator *Mediatorfunc GetMediatorInstance() *Mediator {if mediator == nil {mediator = &Mediator{}}return mediator
}func (m *Mediator) changed(i interface{}) {switch inst := i.(type) {case *CDDriver:m.CPU.Process(inst.Data)case *CPU:m.Sound.Play(inst.Sound)m.Video.Display(inst.Video)}
}

mediator_test.go

package mediatorimport "testing"func TestMediator(t *testing.T) {mediator := GetMediatorInstance()mediator.CD = &CDDriver{}mediator.CPU = &CPU{}mediator.Video = &VideoCard{}mediator.Sound = &SoundCard{}//Tigglemediator.CD.ReadData()if mediator.CD.Data != "music,image" {t.Fatalf("CD unexpect data %s", mediator.CD.Data)}if mediator.CPU.Sound != "music" {t.Fatalf("CPU unexpect sound data %s", mediator.CPU.Sound)}if mediator.CPU.Video != "image" {t.Fatalf("CPU unexpect video data %s", mediator.CPU.Video)}if mediator.Video.Data != "image" {t.Fatalf("VidoeCard unexpect data %s", mediator.Video.Data)}if mediator.Sound.Data != "music" {t.Fatalf("SoundCard unexpect data %s", mediator.Sound.Data)}
}