type GoroutinePool struct {
 2     Queue  chan func() error
 3     Number int
 4     Total  int
 5 
 6     result         chan error
 7     finishCallback func()
 8 }
 9 
10 // 初始化
11 func (self *GoroutinePool) Init(number int,total int) {
12     self.Queue = make(chan func() error,total)
13     self.Number = number
14     self.Total = total
15     self.result = make(chan error,total)
16 }
17 
18 // 开门接客
19 func (self *GoroutinePool) Start() {
20     // 开启Number个goroutine
21     for i := 0; i < self.Number; i++ {
22         go func() {
23             for {
24                 task,ok := <-self.Queue
25                 if !ok {
26                     break
27                 }
28 
29                 err := task()
30                 self.result <- err
31             }
32         }()
33     }
34 
35     // 获得每个work的执行结果
36     for j := 0; j < self.Total; j++ {
37         res,ok := <-self.result
38         if !ok {
39             break
40         }
41 
42         if res != nil {
43             fmt.Println(res)
44         }
45     }
46 
47     // 所有任务都执行完成，回调函数
48     if self.finishCallback != nil {
49         self.finishCallback()
50     }
51 }
52 
53 // 关门送客
54 func (self *GoroutinePool) Stop() {
55     close(self.Queue)
56     close(self.result)
57 }
58 
59 // 添加任务
60 func (self *GoroutinePool) AddTask(task func() error) {
61     self.Queue <- task
62 }
63 
64 // 设置结束回调
65 func (self *GoroutinePool) SetFinishCallback(callback func()) {
66     self.finishCallback = callback
67 }
 

开启3个线程，下载10个文件的测试代码：

 1 func Download_test() {
 2     urls := []string{
 3         "http://dlsw.baidu.com/sw-search-sp/soft/44/17448/Baidusd_Setup_4.2.0.7666.1436769697.exe",4         "http://dlsw.baidu.com/sw-search-sp/soft/3a/12350/QQ_V7.4.15197.0_setup.1436951158.exe",5         "http://dlsw.baidu.com/sw-search-sp/soft/9d/14744/ChromeStandalone_V43.0.2357.134_Setup.1436927123.exe",6         "http://dlsw.baidu.com/sw-search-sp/soft/6f/15752/iTunes_V12.2.1.16_Setup.1436855012.exe",7         "http://dlsw.baidu.com/sw-search-sp/soft/70/17456/BaiduAn_Setup_5.0.0.6747.1435912002.exe",8         "http://dlsw.baidu.com/sw-search-sp/soft/40/12856/QIYImedia_1_06_v4.0.0.32.1437470004.exe",9         "http://dlsw.baidu.com/sw-search-sp/soft/42/37473/BaiduSoftMgr_Setup_7.0.0.1274.1436770136.exe",10         "http://dlsw.baidu.com/sw-search-sp/soft/49/16988/YoudaoNote_V4.1.0.300_setup.1429669613.exe",11         "http://dlsw.baidu.com/sw-search-sp/soft/55/11339/bdbrowserSetup-7.6.100.2089-1212_11000003.1437029629.exe",12         "http://dlsw.baidu.com/sw-search-sp/soft/53/21734/91zhushoupc_Windows_V5.7.0.1633.1436844901.exe",13     }
14 
15     pool := new(GoroutinePool)
16     pool.Init(3,len(urls))
17 
18     for i := range urls {
19         url := urls[i]
20         pool.AddTask(func() error {
21             return download(url)
22         })
23     }
24 
25     isFinish := false
26 
27     pool.SetFinishCallback(func() {
28         func(isFinish *bool) {
29             *isFinish = true
30         }(&isFinish)
31     })
32 
33     pool.Start()
34 
35     for !isFinish {
36         time.Sleep(time.Millisecond * 100)
37     }
38 
39     pool.Stop()
40     fmt.Println("所有操作已完成！")
41 }
42 
43 func download(url string) error {
44     fmt.Println("开始下载... ",url)
45 
46     sp := strings.Split(url,"/")
47     filename := sp[len(sp)-1]
48 
49     file,err := os.Create("/Users/staff/Documents/Red_Test/AAAA/" + filename)
50     if err != nil {
51         return err
52     }
53 
54     res,err := http.Get(url)
55     if err != nil {
56         return err
57     }
58 
59     length,err := io.Copy(file,res.Body)
60     if err != nil {
61         return err
62     }
63 
64     fmt.Println("## 下载完成！ ",url," 文件长度：",length)
65     return nil
66 }