使用golang来实现图片的上传，服务端我们使用gin框架来接收保存图片

服务端

服务端路由

router.POST("/uploadimage", controller.UploadImage)

服务端保存上传的图片

这里设置了一个简单的认证，上传文件的时候需要带一个pass字段里面存储了需要认证的字符串，防止非法上传。
上传的图片设置了最大不能超过5M

func UploadImage(c *gin.Context) {
	var resp RespData
	pass := c.Request.FormValue("pass")
	if pass != "ningto" {
		resp.ErrCode = http.StatusBadRequest
		resp.ErrMsg = "No Auth"
		c.JSON(resp.ErrCode, resp)
		return
	}

	header, err := c.FormFile("file")
	if err != nil {
		resp.ErrCode = http.StatusBadRequest
		resp.ErrMsg = err.Error()
		c.JSON(resp.ErrCode, resp)
		return
	}

	if header.Size > (5 * 1024 * 1024) {
		resp.ErrCode = http.StatusBadRequest
		resp.ErrMsg = fmt.Sprintf("Picture is too big, size:%v bytes", header.Size)
		c.JSON(resp.ErrCode, resp)
		return
	}

	newFilename := fmt.Sprintf("%s-%s", time.Now().Format("20060102"), header.Filename)
	imagePath := path.Join(configs.UploadDir(), newFilename)
	if !util.PathExist(imagePath) {
		if err := c.SaveUploadedFile(header, imagePath); err != nil {
			resp.ErrCode = http.StatusInternalServerError
			resp.ErrMsg = err.Error()
			c.JSON(resp.ErrCode, resp)
			return
		}
	}

	resp.ErrCode = 0
	resp.ErrMsg = ""
	resp.Content = c.Request.Host + "/upload/" + newFilename
	c.JSON(200, resp)
}

服务端应答

统一使用RespData结构来应答，正常为ErrCode为0，失败为非0，ErrMsg是失败的信息，Content是成功后的应答内容。

type RespData struct {
	ErrCode int    `json:"errcode"`
	ErrMsg  string `json:"errmsg"`
	Content string `json:"content"`
}

客户端

客户端直接看代码，从命令行传入两个参数：上传的url和图片路径。

package main

import (
	"bytes"
	"flag"
	"fmt"
	"io"
	"io/ioutil"
	"mime/multipart"
	"net/http"
	"os"
)

func main() {
	var paramImgPath string
	var paramUrl string
	flag.StringVar(&paramUrl, "url", "", "url")
	flag.StringVar(&paramImgPath, "path", "", "image path")
	flag.Parse()

	if len(paramUrl) == 0 || len(paramImgPath) == 0 {
		fmt.Println("url or path is empty")
		return
	}

	data := map[string]string{
		"pass": "ningto",
	}
	b, err := PostFile(paramImgPath, data, paramUrl)
	if err != nil {
		panic(err)
	}

	fmt.Println(string(b))
}

func PostFile(filename string, data map[string]string, targetUrl string) ([]byte, error) {
	bodyBuf := &bytes.Buffer{}
	bodyWriter := multipart.NewWriter(bodyBuf)

	for k, v := range data {
		if err := bodyWriter.WriteField(k, v); err != nil {
			fmt.Println("write filed error, k:", k, ", v:", v)
		}
	}

	// open file handle
	fh, err := os.Open(filename)
	if err != nil {
		fmt.Println("error opening file")
		return []byte{}, err
	}
	defer fh.Close()

	fi, err := fh.Stat()
	if err != nil {
		return []byte{}, err
	}

	// this step is very important
	fileWriter, err := bodyWriter.CreateFormFile("file", fi.Name())
	if err != nil {
		fmt.Println("error writing to buffer")
		return []byte{}, err
	}

	//iocopy
	_, err = io.Copy(fileWriter, fh)
	if err != nil {
		return []byte{}, err
	}

	contentType := bodyWriter.FormDataContentType()
	bodyWriter.Close()

	resp, err := http.Post(targetUrl, contentType, bodyBuf)
	if err != nil {
		return []byte{}, err
	}
	defer resp.Body.Close()
	resp_body, err := ioutil.ReadAll(resp.Body)
	return resp_body, err
}