如何在Golang中实现装饰器模式_Golang装饰器模式实现方法汇总

func LoggingMiddleware(next http.HandlerFunc) http.HandlerFunc {
    return func(w http.ResponseWriter, r *http.Request) {
        log.Printf("Received request: %s %s", r.Method, r.URL.Path)
        next(w, r)
    }
}

func AuthMiddleware(next http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        token := r.Header.Get("Authorization")
        if token == "" {
            http.Error(w, "Unauthorized", http.StatusUnauthorized)
            return
        }
        next.ServeHTTP(w, r)
    })
}

http.HandleFunc("/", LoggingMiddleware(myHandler))
http.Handle("/admin", AuthMiddleware(http.HandlerFunc(adminHandler)))

type Reader interface {
    Read() string
}

type FileReader struct{}

func (f *FileReader) Read() string {
    return "data from file"
}

type CachedReader struct {
    reader Reader
    cache  string
}

func (c *CachedReader) Read() string {
    if c.cache == "" {
        c.cache = c.reader.Read()
        log.Println("Reading from source...")
    } else {
        log.Println("Reading from cache...")
    }
    return c.cache
}

r := &FileReader{}
cachedR := &CachedReader{reader: r}
fmt.Println(cachedR.Read()) // 第一次读源
fmt.Println(cachedR.Read()) // 第二次走缓存

type ServiceFunc func()

func LogDecorator(f ServiceFunc) ServiceFunc {
    return func() {
        log.Println("Before service execution")
        f()
        log.Println("After service execution")
    }
}

func PanicRecoverDecorator(f ServiceFunc) ServiceFunc {
    return func() {
        defer func() {
            if err := recover(); err != nil {
                log.Printf("Recovered from panic: %v", err)
            }
        }()
        f()
    }
}

service := func() {
    fmt.Println("Running business logic")
}

decorated := LogDecorator(PanicRecoverDecorator(service))
decorated()

func RetryDecorator(retries int, fn func() error) func() error {
    return func() error {
        for i := 0; i <= retries; i++ {
            err := fn()
            if err == nil {
                return nil
            }
            log.Printf("Attempt %d failed: %v", i+1, err)
            time.Sleep(time.Second)
        }
        return fmt.Errorf("failed after %d retries", retries)
    }
}

callAPI := func() error {
    // 模拟可能失败的网络请求
    return errors.New("network error")
}

retryCall := RetryDecorator(3, callAPI)
retryCall()