解决golang读取http的body时遇到的坑

func main(){
 url:="http://127.0.0.1:8335/api/v2/submit"
 myReq:= struct {
 ProductId  int  `json:"product_id"`
 Mobile   string `json:"mobile"`
 Content  string  `json:"content"`
 Grade  float64 `form:"grade" json:"grade"`
 Image  string `form:"image" json:"image"`
  Longitude  float64    `json:"longitude"`
 Latitude  float64   `json:"latitude"`
 }{
 ProductId:219,
 Mobile:"15911111111",
 Content: "这个软件LOGO真丑",
 Image: "www.picture.com;www.picture.com",
 Longitude: 106.3037109375,
 Latitude: 38.5137882595,
 Grade:9.9,
 }
 reqByte,err:=json.Marshal(myReq)
 req, err := http.NewRequest("POST", url, bytes.NewReader(reqByte))
 if err != nil {
 return
 }
 //设置请求头
 req.Header.Add("Content-Type", "application/json")
 cli := http.Client{
 Timeout: 45 * time.Second,
 }
 resp, err := cli.Do(req)
 if err != nil {
 return
 }
 out, err := ioutil.ReadAll(resp.Body)
 if err != nil {
 return
 }
 fmt.Println(string(out))
}

func SubmitV2(c *gin.Context) {
 resp := &dto.Response{}
 obj:=make(map[string]interface{})
 var buf []byte
 var err error
 buf, err =ioutil.ReadAll(c. Request.Body)
 if err!=nil {
 return
 }
 err=json.Unmarshal(buf,&obj)
 if err!=nil {
 return
 }
 fmt.Println("product_id:",reflect.TypeOf(obj["product_id"]))
 fmt.Println("image:",reflect.TypeOf(obj["image"]))
 fmt.Println(obj)
 productId:=obj["product_id"].(float64)
 //注意，这里断言成int类型会出错
 c.Request.Body = ioutil.NopCloser(bytes.NewBuffer(buf))
 if !checkProduct(int(productId)){
 resp.Code = -1
 resp.Message = "xxxxxx"
 c.JSON(http.StatusOK, resp)
 return
 }
 url := config.Optional.OpinionHost + "/api/v1/submit"
 err = http_utils.PostAndUnmarshal(url, c.Request.Body, nil, resp)
 if err != nil {
 logrus.WithError(err).Errorln("Submit: error")
 resp.Code = -1
 resp.Message = "Submit"
 }
 c.JSON(http.StatusOK, resp)
}

package main
import (
 "fmt"
 "net/http"
)
func headerBody(rw http.ResponseWriter, r *http.Request) {
 // 获取请求报文的内容长度
 len := r.ContentLength
 // 新建一个字节切片，长度与请求报文的内容长度相同
 body := make([]byte, len)
 // 读取 r 的请求主体，并将具体内容读入 body 中
 r.Body.Read(body)
 // 将字节切片内容写入相应报文
 fmt.Fprintln(rw, body)
}
func main() {
 server := http.Server{
 Addr: "127.0.0.1:http",
 }
 http.HandleFunc("/", headerBody)
 server.ListenAndServe()
}