GO语言练习：第二个工程--模拟音乐播放器

1、代码

2、编译及运行

---

1、目录结构

　　1.1）

 $ tree
 .
 ├── mplayer.go
 └── src
     ├── mlib
     │   ├── manager.go
     │   └── manager_test.go
     └── mp
         ├── mp3.go
         └── play.go

　　1.2）mlib库的代码

　　　　1.2.1）manager.go代码

 package library

 import "errors"

 type MusicEntry struct {
     Id        string
     Name    string
     Artist    string
     Genre    string
     Source    string
     Type    string
 }

 type MusicManager struct {
     musics []MusicEntry
 }

 func NewMusicManager() * MusicManager {
     return &MusicManager {make( []MusicEntry, 0)}
 }

 func (m * MusicManager) Len() int {
     return len(m.musics);
 }

 func (m* MusicManager ) Get(index int) (music * MusicEntry, err error) {
     if index < 0 || index >= len(m.musics) {
         return nil, errors.New("Index out of range.")
     }

     return &m.musics[index], nil
 }

 func (m * MusicManager) Find (name string) * MusicEntry {
     if len(m.musics) == 0 {
         return nil
     }

     for _,m := range m.musics {
         if m.Name == name {
             return &m
         }
     }
     return nil
 }

 func (m * MusicManager) Add (music * MusicEntry) {
     m.musics = append(m.musics, * music)
 }

 func (m * MusicManager) Remove (index int) * MusicEntry {
     if index < 0 || index >= len(m.musics) {
         return nil
     }
     removedMusic := &m.musics[index]

     if index < len(m.musics) - 1 {
         m.musics = append(m.musics[:index - 1], m.musics[index + 1:]...)
     }else if index == 0 {
         m.musics = make([]MusicEntry, 0)
     } else {
         m.musics = m.musics[:index - 1]
     }

     return removedMusic
 }

 func (m * MusicManager) RemoveByName (name string) * MusicEntry {
     var removedMusic * MusicEntry = nil
     var iPos int = -1
     for i := 0; i < m.Len(); i++ {
         if m.musics[i].Name == name {
             iPos = i
             break
         }
     }

     if iPos < 0 {
         return nil
     }

     removedMusic = m.Remove(iPos)

     return removedMusic
 }

　　1.2.2）manager.go的测试代码manager_test.go

 package library

 import (
     "testing"
 )

 func TestOps(t * testing.T) {
     mm := NewMusicManager()
     if mm == nil {
         t.Error("NewMusicManager faild.");
     }
     if mm.Len() != 0 {
         t.Error("NewMusicManager faild, not empty")
     }
     m0 := &MusicEntry { "1", "My Heart Will Go On", "Celion Dion", "Pop", "http://qbox.me/24501234", "MP3" }
     mm.Add(m0)

     if mm.Len() != 1 {
         t.Error("MusicManager.Add faild.")
     }

     m := mm.Find(m0.Name)
     if m == nil {
         t.Error("MusicManager.Find faild")
     }

     if    m.Id != m0.Id ||
         m.Name != m0.Name ||
         m.Artist != m0.Artist ||
         m.Genre != m0.Genre ||
         m.Source != m0.Source ||
         m.Type != m0.Type {
             t.Error("MusicManager.Find() faild. Found item mismatch.")
     }

     m, err := mm.Get(0)
     if m == nil {
         t.Error("MusicManager.Get() faild.", err)
     }

     m = mm.Remove(0)
     if m == nil || mm.Len() != 0 {
         t.Error("MusicManager.Remove() faild.", err)
     }
 }

　　1.3）mp库代码

　　　　1.3.1）src/mp/mp3.go代码

 package mp

 import (
     "fmt"
     "time"
 )

 type MP3Player struct {
     stat int
     progress int
 }

 type WAVPlayer struct {
     stat int
     progress int
 }

 func (p * MP3Player) Play (source string) {
     fmt.Println("Playing MP3 music", source)

     p.progress = 0

     for p.progress < 100 {
         time.Sleep(100 * time.Millisecond)
         fmt.Print(".")
         p.progress += 10
     }
     fmt.Println("\nFinished playing", source)
 }

 func (p * WAVPlayer) Play (source string) {
     fmt.Println("Playing WAV music", source)

     p.progress = 0

     for p.progress < 100 {
         time.Sleep(100 * time.Millisecond)
         fmt.Print(".")
         p.progress += 10
     }
     fmt.Println("\nFinished playing", source)
 }

　　　　1.3.2）src/mp/play.go代码

 package mp

 import "fmt"

 type Player interface {
     Play(source string)
 }

 func Play(source, mtype string) {
     var p Player

     switch mtype {
     case "MP3" :
         p = &MP3Player{}
     case "WAV" :
         p = &WAVPlayer{}
         default :
         fmt.Println("Unsupported music type", mtype)
         return
     }
     p.Play(source)
 }

　　1.4）main package模块代码mplayer.go

 package main

 import (
     "bufio"
     "fmt"
     "os"
     "strconv"
     "strings"

     "mlib"
     "mp"
 )

 var lib * library.MusicManager
 var id int = 1
 var ctrl, signal chan int

 func handleLibCommands(tokens []string) {
     switch tokens[1] {
     case "list" :
         for i := 0; i < lib.Len(); i++ {
             e, _ := lib.Get(i)
             fmt.Println(i + 1, ":", e.Name, e.Artist, e.Source, e.Type)
         }
     case "add" :
         if len(tokens) == 7 {
             id++
             lib.Add(&library.MusicEntry { strconv.Itoa(id), tokens[2], tokens[3], tokens[4], tokens[5], tokens[6] })
         } else {
             fmt.Println("USAGE : lib add <name><artist><genre><source><type> (7 argv)")
         }
     case "remove" :
         if len(tokens) == 3 {
             lib.RemoveByName(tokens[2])
         } else {
             fmt.Println("USAGE: lib remove <name>")
         }
         default :
         fmt.Println("Unrecogized lib command: ", tokens[1])
     }
 }

 func handlePlayCommands(tokens []string) {
     if len(tokens) != 2 {
         fmt.Println("USAGE : play <name>")
         return
     }

     e := lib.Find(tokens[1])
     if e == nil {
         fmt.Println("The music", tokens[1], "does not exist.")
         return
     }

     mp.Play(e.Source, e.Type)
 }

 func main() {
     fmt.Println(`
     Enter following commands to control the player:
     lib list --View the existing music lib
     lib add <name><artist><genre><source><type> -- Add a music to the music lib
     lib remove <name> --Remove the specified music from the lib
     play <name> -- Play the specified music
     `)
     lib = library.NewMusicManager()

     r := bufio.NewReader(os.Stdin)

     for i := 0; i <= 100; i++ {
         fmt.Print("Enter command-> ")
         rawLine, _, _ := r.ReadLine()

         line := string(rawLine)
         if line == "q" || line == "e" {
             break
         }
         tokens := strings.Split(line, " ")

         if tokens[0] == "lib" {
             handleLibCommands(tokens)
         } else if tokens[0] == "play" {
             handlePlayCommands(tokens)
         } else {
             fmt.Println("Unrecognized command :", tokens[0])
         }
     }
 }

　　2）编译及运行

　　　　2.1）设置环境GOPATH

$ export GOPATH="/home/normal/musicplayer"

　　　　2.2）编译

 $ go build

　　　　2.3）查看编译后的目录结构

 .
 ├── mplayer.go
 ├── musicplayer
 └── src
     ├── mlib
     │   ├── manager.go
     │   └── manager_test.go
     └── mp
         ├── mp3.go
         └── play.go

　　　　2.4）运行

$ ./musicplayer 

    Enter following commands to control the player:
    lib list --View the existing music lib
    lib add <name><artist><genre><source><type> -- Add a music to the music lib
    lib remove <name> --Remove the specified music from the lib
    play <name> -- Play the specified music

Enter command-> lib add a b c d e
Enter command-> lib list
 : a b d e
Enter command-> play a
Unsupported music type e
Enter command-> lib remove a
Enter command-> lib add a b c d e MP3
USAGE : lib add <name><artist><genre><source><type> ( argv)
Enter command-> lib add a b c d MP3
Enter command-> lib list
 : a b d MP3
Enter command-> play a
Playing MP3 music d
..........
Finished playing d
Enter command-> q

注：代码来源《Go语言编程》第三章，代码结构与原书有差别