1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77

package main

import "fmt"

// 抽象
type computer interface {
	print()
	setPrinter(printer)
}

// 精确抽象
type mac struct {
	printer printer
}

func (m *mac) print() {
	fmt.Println("Print request for mac")
	m.printer.printFile()
}

func (m *mac) setPrinter(p printer) {
	m.printer = p
}

// 精确抽象
type windows struct {
	printer printer
}

func (w *windows) print() {
	fmt.Println("Print request for windows")
	w.printer.printFile()
}

func (w *windows) setPrinter(p printer) {
	w.printer = p
}

// 实施
type printer interface {
	printFile()
}

// 具体实施
type epson struct{}

func (p *epson) printFile() {
	fmt.Println("Printing by a EPSON Printer")
}

// 具体实施
type hp struct{}

func (p *hp) printFile() {
	fmt.Println("Printing by a HP Printer")
}

// 客户端调用
func main() {
	macComputer := &mac{}
	macComputer.setPrinter(&hp{})
	macComputer.print()
	fmt.Println()

	macComputer.setPrinter(&epson{})
	macComputer.print()
	fmt.Println()

	winComputer := &windows{}
	winComputer.setPrinter(&hp{})
	winComputer.print()
	fmt.Println()

	winComputer.setPrinter(&epson{})
	winComputer.print()
	fmt.Println()
}