03. 中介者模式
<p>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。</p>
<p>例子中的中介者使用单例模式生成中介者。</p>
<p>中介者的change使用switch判断类型。</p>
<h4>mediator.go</h4>
<pre><code>package mediator
import (
"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 string
Sound 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 = data
fmt.Printf("VideoCard: display %s\n", v.Data)
GetMediatorInstance().changed(v)
}
type SoundCard struct {
Data string
}
func (s *SoundCard) Play(data string) {
s.Data = data
fmt.Printf("SoundCard: play %s\n", s.Data)
GetMediatorInstance().changed(s)
}
type Mediator struct {
CD *CDDriver
CPU *CPU
Video *VideoCard
Sound *SoundCard
}
var mediator *Mediator
func 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)
}
}</code></pre>
<h4>mediator_test.go</h4>
<pre><code>package mediator
import "testing"
func TestMediator(t *testing.T) {
mediator := GetMediatorInstance()
mediator.CD = &CDDriver{}
mediator.CPU = &CPU{}
mediator.Video = &VideoCard{}
mediator.Sound = &SoundCard{}
//Tiggle
mediator.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)
}
}</code></pre>