module goStudy1

go 1.17

package main

import (
	"fmt"
	"os"
	"strconv"

	//"github.com/thinkeridea/go-extend/exnet"
	"io"
	"log"
	"net/http"
	"strings"
)

/*
編寫一個 HTTP 服務器，4個功能：

	1，接收客戶端 request，并將 request 中帶的 header 寫入 response header
	2，讀取當前系統的環境變量中的 VERSION 配置，并寫入 response header
	3，Server 端記錄訪問日志包括客戶端 IP，HTTP 返回碼，輸出到 server 端的標準輸出
	4，當訪問 localhost/healthz 時，應返回 200
*/

// Main方法入口
func main() {
	println("環境正常")

	// 功能1
	http.HandleFunc("/requestAndResponse", requestAndResponse)

	// 功能2
	http.HandleFunc("/getVersion", getVersion)

	// 功能3
	http.HandleFunc("/ipAndStatus", ipAndStatus) //注冊接口句柄

	// 功能4
	http.HandleFunc("/healthz", healthz) //注冊接口句柄

	err := http.ListenAndServe(":81", nil) //監聽空句柄，80端口被占用，使用81端口
	if nil != err {
		log.Fatal(err) //顯示錯誤日志
	}
}

// 功能1，接收請求及響應
func requestAndResponse(response http.ResponseWriter, request *http.Request) {
	println("調用requestAndResponse接口")
	headers := request.Header //header是Map類型的數據
	println("傳入的hander：")
	for header := range headers { //value是[]string
		//println("header的key：" + header)
		values := headers[header]
		for index, _ := range values {
			values[index] = strings.TrimSpace(values[index])
			//println("index=" + strconv.Itoa(index))
			//println("header的value：" + values[index])

		}
		//valueString := strings.Join(values, "")
		//println("header的value：" + valueString)
		println(header + "=" + strings.Join(values, ","))        //打印request的header的k=v
		response.Header().Set(header, strings.Join(values, ",")) // 遍歷寫入response的Header
		//println()

	}
	fmt.Fprintln(response, "Header全部數據:", headers)
	io.WriteString(response, "succeed")

}

// 功能2，獲取環境變量的version
func getVersion(response http.ResponseWriter, request *http.Request) {
	println("調用getVersion接口")
	envStr := os.Getenv("VERSION")
	//envStr := os.Getenv("HADOOP_HOME")
	//println("系統環境變量：" + envStr) //可以看到 C:\soft\hadoop-3.3.1	Win10需要重啟電腦才能生效

	response.Header().Set("VERSION", envStr)
	io.WriteString(response, "succeed")

}

// 功能3，輸出IP與返回碼
func ipAndStatus(response http.ResponseWriter, request *http.Request) {
	println("調用ipAndStatus接口")

	form := request.RemoteAddr
	println("Client->ip:port=" + form) //虛擬機是橋接模式。使用postman返回的全部是127.0.0.1	用手機打開網站192.168.1.139:81/ipAndStatus可以看到新IP
	ipStr := strings.Split(form, ":")
	println("Client->ip=" + ipStr[0]) //打印ip

	// 獲取http響應碼
	//response.WriteHeader(301) //手動設置響應碼，默認200

	//response.WriteHeader(http.StatusOK)//由于默認是調用這個，∴返回碼都是這個200【server.go有源碼】
	println("Client->response code=" + strconv.Itoa(http.StatusOK))

	//println("response code->：" + code)

	io.WriteString(response, "succeed")
}

// 功能4，連通性測試接口
func healthz(response http.ResponseWriter, request *http.Request) {
	println("調用healthz接口")
	response.WriteHeader(200) //設置返回碼200
	//response.WriteHeader(http.StatusOK)//默認會調用這個方法，默認就是200【server.go有源碼】
	io.WriteString(response, "succeed")
}

	//envStr := os.Getenv("VERSION")
	envStr := os.Getenv("HADOOP_HOME")

環境正常
調用getVersion接口
調用ipAndStatus接口
Client->ip:port=127.0.0.1:59595
Client->ip=127.0.0.1
Client->response code=200      
調用ipAndStatus接口
Client->ip:port=192.168.1.138:37548
Client->ip=192.168.1.138
Client->response code=200

	// WriteHeader sends an HTTP response header with the provided
	// status code.
	//
	// If WriteHeader is not called explicitly, the first call to Write
	// will trigger an implicit WriteHeader(http.StatusOK).
	// Thus explicit calls to WriteHeader are mainly used to
	// send error codes.
	//
	// The provided code must be a valid HTTP 1xx-5xx status code.
	// Only one header may be written. Go does not currently
	// support sending user-defined 1xx informational headers,
	// with the exception of 100-continue response header that the
	// Server sends automatically when the Request.Body is read.
	WriteHeader(statusCode int)