golang http文件上传操作

1. beego作为服务器
2. 通过post formData的格式上传

报文格式如下：

package main

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

func main() {
	req, _ := newfileUploadRequest("http://192.168.2.144:8956/v1/body-eval/data-info", nil, "file_name", "1.txt")
	client := &http.Client{}
	fmt.Println(req)
	resp, err := client.Do(req)

	defer resp.Body.Close()

	body, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		// handle error
	}

	fmt.Println(string(body))
}

func newfileUploadRequest(uri string, params map[string]string, paramName, path string) (*http.Request, error) {
	file, err := os.Open(path)
	if err != nil {
		return nil, err
	}
	defer file.Close()

	body := &bytes.Buffer{}
	writer := multipart.NewWriter(body)
	part, err := writer.CreateFormFile(paramName, path)
	if err != nil {
		return nil, err
	}
	_, err = io.Copy(part, file)

	for key, val := range params {
		_ = writer.WriteField(key, val)
	}
	err = writer.Close()
	if err != nil {
		return nil, err
	}
	request, err := http.NewRequest("POST", uri, body)
	request.Header.Set("Content-Type", writer.FormDataContentType())
	return request, err
}