pro-go-study/25-httpclient/httpclient/main.go

package main

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

func main() {
	mainInit()
	main1()
	main2()
	main3()
	main4()
	main5()
	main6()
	main7()
	main8()
	main9()
	main10()
}

func mainInit() {
	Printfln("Starting HTTP Server")
	go http.ListenAndServe("localhost:5000", nil)

	time.Sleep(time.Second)
}

func main1() {
	Printfln("\n\nmain1:")
	response, err := http.Get("http://localhost:5000/html")
	if err != nil {
		Printfln("Error: %v", err.Error())
		return
	}

	Printfln("Status: %v", response.Status)
	Printfln("Headers: %v", response.Header)

	Printfln("\n response.Write: ------  ")
	response.Write(os.Stdout)
}

func main2() {
	Printfln("\n\nmain2:")
	response, err := http.Get("http://localhost:5000/html")
	if err != nil {
		Printfln("Error: %v", err.Error())
		return
	}

	Printfln("\n response.Body: ------ ")
	body := response.Body
	defer body.Close()
	data, err := io.ReadAll(body)
	if err != nil {
		Printfln("Error: %v", err.Error())
		return
	}
	os.Stdout.Write(data)
}

func main3() {
	Printfln("\n\nmain3:")
	response, err := http.Get("http://localhost:5000/json")
	if err != nil {
		Printfln("Error: %v", err.Error())
		return
	}
	if response.StatusCode != http.StatusOK {
		Printfln("Status Code: %v", response.StatusCode)
		return
	}
	var products []Product
	err = json.NewDecoder(response.Body).Decode(&products)
	if err != nil {
		Printfln("Decode Error: %v", err.Error())
		return
	}
	for _, p := range products {
		Printfln("Name: %v ,Category : %v , Price: $%.2f", p.Name, p.Category, p.Price)
	}
}

func main4() {
	Printfln("\n\nmain4:")

	formData := map[string][]string{
		"name":     {"Kayak"},
		"category": {"Watersports"},
		"price":    {"279"},
	}

	response, err := http.PostForm("http://localhost:5000/echo", formData)
	if err != nil {
		Printfln("Error: %v", err.Error())
		return
	}
	if response.StatusCode != http.StatusOK {
		Printfln("Status Code: %v", response.StatusCode)
		return
	}
	defer response.Body.Close()
	io.Copy(os.Stdout, response.Body)
}

func main5() {
	Printfln("\n\nmain5:")

	var builder strings.Builder
	err := json.NewEncoder(&builder).Encode(&Kayak)
	if err != nil {
		Printfln("Encoder Error: %v", err.Error())
		return
	}

	reqUrl, err := url.Parse("http://localhost:5000/echo")
	if err != nil {
		Printfln("URL Parse Error: %v", err.Error())
		return
	}
	req := &http.Request{
		Method: "POST",
		URL:    reqUrl,
		Header: map[string][]string{
			"Content-Type": {"application/json"},
		},
		Body: io.NopCloser(strings.NewReader(builder.String())),
	}
	response, err := http.DefaultClient.Do(req)
	if err != nil {
		Printfln("Response Error: %v", err.Error())
		return
	}
	if response.StatusCode != http.StatusOK {
		Printfln("Status Code: %v", response.StatusCode)
		return
	}
	defer response.Body.Close()
	io.Copy(os.Stdout, response.Body)
}

func main6() {
	Printfln("\n\nmain6:")

	var builder strings.Builder
	err := json.NewEncoder(&builder).Encode(&Kayak)
	if err != nil {
		Printfln("Encoder Error: %v", err.Error())
		return
	}

	req, err := http.NewRequest(http.MethodPost, "http://localhost:5000/echo", strings.NewReader(builder.String()))
	if err != nil {
		Printfln("Request Init Error: %v", err.Error())
		return
	}
	req.Header.Add("Content-Type", "application/json")
	response, err := http.DefaultClient.Do(req)
	if err != nil {
		Printfln("Response Error: %v", err.Error())
		return
	}
	defer response.Body.Close()
	if response.StatusCode != http.StatusOK {
		Printfln("Status Code: %v", response.StatusCode)
		return
	}
	io.Copy(os.Stdout, response.Body)
}

func main7() {
	Printfln("\n\nmain7:")
	jar, err := cookiejar.New(nil)
	if err != nil {
		Printfln("Cookie Error: %v", err.Error())
		return
	}
	http.DefaultClient.Jar = jar

	for i := 0; i < 3; i++ {
		Printfln("\nRequest #%v --------", i+1)
		req, err := http.NewRequest(http.MethodGet, "http://localhost:5000/cookie", nil)
		if err != nil {
			Printfln("Request Init Error: %v", err.Error())
			continue
		}
		response, err := http.DefaultClient.Do(req)
		if err != nil {
			Printfln("Response Error: %v", err.Error())
			continue
		}
		defer response.Body.Close()
		if response.StatusCode != http.StatusOK {
			Printfln("Status Code: %v", response.StatusCode)
			continue
		}
		io.Copy(os.Stdout, response.Body)

		cookies := jar.Cookies(req.URL)
		for _, c := range cookies {
			Printfln("\n Http Client Response Cookie: %v = %v", c.Name, c.Value)
		}
	}
}

func main8() {
	Printfln("\n\nmain8:")

	req, err := http.NewRequest(http.MethodGet, "http://localhost:5000/redirect1", nil)
	if err != nil {
		Printfln("Request Init Error: %v", err.Error())
		return
	}
	response, err := http.DefaultClient.Do(req)
	if err != nil {
		Printfln("Response Error: %v", err.Error())
		return
	}
	defer response.Body.Close()
	if response.StatusCode != http.StatusOK {
		Printfln("Status Code: %v", response.StatusCode)
		return
	}
	io.Copy(os.Stdout, response.Body)
}

func main9() {
	Printfln("\n\nmain9:")
	defer func() {
		http.DefaultClient.CheckRedirect = nil
	}()
	http.DefaultClient.CheckRedirect = func(req *http.Request, previous []*http.Request) error {
		if len(previous) == 3 {
			for _, r := range previous {
				Printfln("Previous Request: %v", r.URL.String())
			}
			Printfln("Now Request: %v", req.URL.String())
			u, _ := url.Parse("http://localhost:5000/html")
			req.URL = u
		}
		return nil
	}
	req, err := http.NewRequest(http.MethodGet, "http://localhost:5000/redirect1", nil)
	if err != nil {
		Printfln("Request Init Error: %v", err.Error())
		return
	}
	response, err := http.DefaultClient.Do(req)
	if err != nil {
		Printfln("Response Error: %v", err.Error())
		return
	}
	defer response.Body.Close()
	if response.StatusCode != http.StatusOK {
		Printfln("Status Code: %v", response.StatusCode)
		return
	}
	io.Copy(os.Stdout, response.Body)
}

func main10() {
	Printfln("\n\nmain10:")

	var buffer bytes.Buffer
	formWriter := multipart.NewWriter(&buffer)
	fieldWriter, err := formWriter.CreateFormField("name")
	if err == nil {
		io.WriteString(fieldWriter, "Yanzuoguang")
	}
	fieldWriter, err = formWriter.CreateFormField("city")
	if err == nil {
		io.WriteString(fieldWriter, "重庆")
		io.WriteString(fieldWriter, "渝北区")
	}
	fieldWriter, err = formWriter.CreateFormField("city")
	if err == nil {
		io.WriteString(fieldWriter, "上海")
	}
	fileWriter, err := formWriter.CreateFormFile("file", "printer.go")
	if err == nil {
		file, err := os.Open("printer.go")
		if err == nil {
			defer file.Close()
			io.Copy(fileWriter, file)
		}
	}
	fileWriter, err = formWriter.CreateFormFile("file", "go.mod")
	if err == nil {
		file, err := os.Open("go.mod")
		if err == nil {
			defer file.Close()
			io.Copy(fileWriter, file)
		}
	}
	formWriter.Close()

	req, err := http.NewRequest(http.MethodPost, "http://localhost:5000/form", &buffer)
	if err == nil {
		req.Header.Add("Content-Type", formWriter.FormDataContentType())
		response, err := http.DefaultClient.Do(req)
		if err == nil {
			io.Copy(os.Stdout, response.Body)
		} else {
			Printfln("Response Error: %v", err.Error())
		}
	} else {
		Printfln("Request Init Error: %v", err.Error())
	}

}