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("
Finished 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("
Finished 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
1 : 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> (7 argv)
Enter command-> lib add a b c d MP3
Enter command-> lib list
1 : 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