1、URL格式

package main

import (
    "fmt"
    "io"
    "mime"
    "net/http"
    "path"
)

func main() {
    res, err := GetFileInfo("https://pic.616pic.com/ys_bnew_img/00/02/37/PlF9pGxaEh.jpg")
    if err != nil {
        fmt.Println("Error:", err)
        return
    }
    fmt.Println(res)
}

type FileInfo struct {
    FileName string `json:"fileName"`
    FileSize string `json:"fileSize"`
    Mimetype string `json:"mimetype"`
}

func GetFileInfo(url string) (res *FileInfo, err error) {
    res = new(FileInfo)
    resp, err := http.Get(url)
    if err != nil {
        return nil, err
    }
    defer resp.Body.Close()

    // 读取响应体的前 512 个字节
    buf := make([]byte, 512)
    _, err = io.ReadFull(resp.Body, buf)
    if err != nil {
        return
    }

    // 使用 http.DetectContentType 检测 MIME 类型
    res.Mimetype = http.DetectContentType(buf)
    fmt.Println("Mimetype:", res.Mimetype)
    contentDisposition := resp.Header.Get("Content-Disposition")
    _, params, errs := mime.ParseMediaType(contentDisposition)
    if errs != nil {
        // 如果 Content-Disposition 不可用，从 URL 解析文件名
        res.FileName = path.Base(url)
        fmt.Println("Filename path.Base:", res.FileName)

        // 解析后缀名
        fileExt := path.Ext(url)
        fmt.Println("File Extension2:", fileExt)
    } else {
        // 如果 Content-Disposition 可用，使用它获取文件名
        fileName, ok := params["filename"]
        if ok {
            res.FileName = fileName
            fmt.Println("Filename params: ", fileName)

            // 解析后缀名
            fileExt := path.Ext(fileName)
            fmt.Println("File Extension1:", fileExt)
        }
    }

    // 获取文件大小
    res.FileSize = resp.Header.Get("Content-Length")
    if res.FileSize != "" {
        fmt.Println("fileSize Content Length:", res.FileSize)
    } else {
        fmt.Println("Content Length not provided")
    }

    return
}

2、本地文件路径

package main

import (
    "fmt"
    "mime"
    "os"
    "path/filepath"
    "github.com/spf13/cast"
)

func main() {
    res, err := GetFileInfo("./img/WechatIMG8.jpg")
    if err != nil {
        fmt.Println("Error:", err)
        return
    }
    fmt.Print(res)
}

type FileInfo struct {
    FileName string `json:"fileName"`
    FileSize string `json:"fileSize"`
    Mimetype string `json:"mimetype"`
}

func GetFileInfo(url string) (res *FileInfo, err error) {
    res = new(FileInfo)
    extension := filepath.Ext(url)
    res.Mimetype = mime.TypeByExtension(extension)
    var file *os.File
    file, err = os.Open(url)
    if err != nil {
        return nil, err
    }
    defer file.Close()
    var fileInfo os.FileInfo
    fileInfo, err = file.Stat()
    if err != nil {
        return
    }
    res.FileName = fileInfo.Name()
    if err != nil {
        return
    }
    res.FileSize = cast.ToString(fileInfo.Size())
    if err != nil {
        return
    }

    return
}