post请求

server端

package main

import (
	"crypto/rand"
	"fmt"
	"html/template"
	"io"
	"log"
	"net/http"
	"os"
)

const maxBytes = 2 * 1024 * 1024 // 2 MB
const uploadPath = "./tmp"

func randToken(len int) string {
	b := make([]byte, len)
	_, _ = rand.Read(b)
	return fmt.Sprintf("%x", b)
}

func uploadHandler() http.HandlerFunc {
	return func(w http.ResponseWriter, req *http.Request) {
		http.MaxBytesReader(w, req.Body, maxBytes)
		if err := req.ParseMultipartForm(maxBytes); err != nil {
			log.Printf("req.ParseMultipartForm: %v", err)
			return
		}

		file, _, err := req.FormFile("uploadFile")
		if err != nil {
			log.Printf("req.FormFile: %v", err)
			return
		}
		defer func() { _ = file.Close()}()

		f, _ := os.Create("poloxue.txt")
		defer func() {_ = f.Close()}()
		_, _ = io.Copy(f, file)

		fmt.Println(req.FormValue("words"))
	}
}

func main() {
	http.HandleFunc("/", func(w http.ResponseWriter, req *http.Request) {
		tpl, err := template.ParseFiles("./form.html")
		if err != nil {
			log.Printf("template.New: %v", err)
			return
		}

		if err := tpl.Execute(w, nil); err != nil {
			log.Printf("tpl.Execute: %v", err)
			return
		}
	})
	http.HandleFunc("/upload", uploadHandler())

	fs := http.FileServer(http.Dir(uploadPath))
	http.Handle("/files", http.StripPrefix("/files", fs))

	log.Println("Server started on localhost:8080, use /upload for uploading files and /files/{filename} for downloading files.")

	log.Fatal(http.ListenAndServe(":8080", nil))
}

 客户端

package main

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"io/ioutil"
	"mime/multipart"
	"net/http"
	"net/url"
	"os"
	"strings"
)

func postForm() {
	// form data 形式 query string，类似于 name=poloxue&age=18
	data := make(url.Values)
	data.Add("name", "poloxue")
	data.Add("age", "18")
	payload := data.Encode()

	r, _ := http.Post(
		"http://httpbin.org/post",
		"application/x-www-form-urlencoded",
		strings.NewReader(payload),
	)
	defer func() { _ = r.Body.Close() }()

	content, _ := ioutil.ReadAll(r.Body)
	fmt.Printf("%s", content)
}

func postJson() {
	u := struct {
		Name string `json:"name"`
		Age  int    `json:"age"`
	}{
		Name: "poloxue",
		Age:  18,
	}
	payload, _ := json.Marshal(u)
	r, _ := http.Post(
		"http://httpbin.org/post",
		"application/json",
		bytes.NewReader(payload),
	)
	defer func() { _ = r.Body.Close() }()

	content, _ := ioutil.ReadAll(r.Body)
	fmt.Printf("%s", content)
}

func postFile() {
	body := &bytes.Buffer{}

	writer := multipart.NewWriter(body)
	_ = writer.WriteField("words", "123")

	// 一个是输入表单的 name，一个上传的文件名称
	upload1Writer, _ := writer.CreateFormFile("uploadfile1", "uploadfile1")

	uploadFile1, _ := os.Open("uploadfile1")
	defer func() {_ = uploadFile1.Close()}()

	_, _ = io.Copy(upload1Writer, uploadFile1)

	// 一个是输入表单的 name，一个上传的文件名称
	upload2Writer, _ := writer.CreateFormFile("uploadfile2", "uploadfile2")

	uploadFile2, _ := os.Open("uploadfile2")
	defer func() {_ = uploadFile2.Close()}()

	_, _ = io.Copy(upload2Writer, uploadFile2)

	_ = writer.Close()

	fmt.Println(writer.FormDataContentType())
	fmt.Println(body.String())
	r, _ := http.Post("http://httpbin.org/post",
		writer.FormDataContentType(),
		body,
	)
	defer func() {_ = r.Body.Close()}()

	content, _ := ioutil.ReadAll(r.Body)

	fmt.Printf("%s", content)
}

func main() {
	// post 请求的本质，它是 request body 提交，相对于 get 请求（urlencoded 提交查询参数, 提交内容有大小限制，好像 2kb）
	// post 不同的形式也就是 body 的格式不同
	// post form 表单，body 就是 urlencoded 的形式，比如 name=poloxue&age=18
	// post json，提交的 json 格式
	// post 文件，其实也是组织 body 数据
	// postJson()
	postFile()
}