Golang如何构建简易的笔记应用

type Note struct {
    Title     string    `json:"title"`
    Content   string    `json:"content"`
    CreatedAt time.Time `json:"created_at"`
}

func saveNotes(notes []Note) error {
    data, err := json.MarshalIndent(notes, "", "  ")
    if err != nil {
        return err
    }
    return ioutil.WriteFile("notes.json", data, 0644)
}

func loadNotes() ([]Note, error) {
    var notes []Note
    data, err := ioutil.ReadFile("notes.json")
    if err != nil {
        return notes, nil // 文件不存在时返回空列表
    }
    json.Unmarshal(data, &notes)
    return notes, nil
}

func addNote(title, content string) error {
    notes, err := loadNotes()
    if err != nil {
        return err
    }
    newNote := Note{
        Title:     title,
        Content:   content,
        CreatedAt: time.Now(),
    }
    notes = append(notes, newNote)
    return saveNotes(notes)
}

func main() {
    args := os.Args[1:]
    if len(args) < 1 {
        fmt.Println("Usage: note add|list|find [args...]")
        return
    }
<pre class='brush:php;toolbar:false;'>switch args[0] {
case "add":
    if len(args) != 3 {
        fmt.Println("Usage: note add <title> <content>")
        return
    }
    err := addNote(args[1], args[2])
    if err != nil {
        fmt.Println("Error:", err)
    } else {
        fmt.Println("Note added.")
    }
case "list":
    notes, _ := loadNotes()
    for _, n := range notes {
        fmt.Printf("- %s (%s)\n", n.Title, n.CreatedAt.Format("2006-01-02"))
    }
case "find":
    if len(args) != 2 {
        fmt.Println("Usage: note find <title>")
        return
    }
    notes, _ := loadNotes()
    for _, n := range notes {
        if strings.Contains(strings.ToLower(n.Title), strings.ToLower(args[1])) {
            fmt.Printf("Title: %s\nCreated: %s\nContent: %s\n\n",
                n.Title, n.CreatedAt.Format("2006-01-02"), n.Content)
        }
    }
default:
    fmt.Println("Unknown command")
}

go build -o note main.go
./note add "Meeting" "Discuss project timeline"
./note list
./note find "meet"