func uploadHandler(w http.ResponseWriter, r *http.Request) {
    if r.Method != "POST" {
        http.Error(w, "只允许POST请求", http.StatusMethodNotAllowed)
        return
    }

    // 解析 multipart 表单，最大内存32MB
    err := r.ParseMultipartForm(32 << 20)
    if err != nil {
        http.Error(w, "解析表单失败", http.StatusBadRequest)
        return
    }

    file, handler, err := r.FormFile("file")
    if err != nil {
        http.Error(w, "获取文件失败", http.StatusBadRequest)
        return
    }
    defer file.Close()

    // 创建保存文件
    f, err := os.Create("./uploads/" + handler.Filename)
    if err != nil {
        http.Error(w, "创建文件失败", http.StatusInternalServerError)
        return
    }
    defer f.Close()

    // 写入文件
    _, err = io.Copy(f, file)
    if err != nil {
        http.Error(w, "保存文件失败", http.StatusInternalServerError)
        return
    }

    w.Write([]byte("文件上传成功"))
}

files := r.MultipartForm.File["files"]
for _, fh := range files {
    src, err := fh.Open()
    if err != nil {
        continue
    }
    defer src.Close()

    dst, err := os.Create("./uploads/" + fh.Filename)
    if err != nil {
        continue
    }
    defer dst.Close()

    io.Copy(dst, src)
}

func main() {
    http.HandleFunc("/upload", uploadHandler)
    os.MkdirAll("./uploads", os.ModePerm)
    http.ListenAndServe(":8080", nil)
}

curl -X POST -F "file=@./test.jpg" http://localhost:8080/upload