<form action="/upload" method="post" enctype="multipart/form-data">
  <input type="file" name="files" multiple>
  <button type="submit">上传文件</button>
</form>

func uploadHandler(w http.ResponseWriter, r *http.Request) {
    if r.Method != "POST" {
        http.Error(w, "仅支持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
    }

    files := r.MultipartForm.File["files"]

    for _, fileHeader := range files {
        // 打开上传的文件
        file, err := fileHeader.Open()
        if err != nil {
            http.Error(w, "无法打开文件", http.StatusInternalServerError)
            return
        }
        defer file.Close()

        // 创建本地保存的目标文件
        dst, err := os.Create("./uploads/" + fileHeader.Filename)
        if err != nil {
            http.Error(w, "创建文件失败", http.StatusInternalServerError)
            return
        }
        defer dst.Close()

        // 复制文件内容
        _, err = io.Copy(dst, 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"))
}