Go语言实现的简单Web Services（接上一篇代码讲解示例）

Go语言实现WebService(添加Json格式化例子)

1. 代码如下

package main
import (
	"bufio"
	"encoding/json"
	"fmt"
	"log"
	"net"
	"net/http"
	"strconv"
)
//定义自己的路由器
type MyMux struct{

}
type point struct {
	Metric string			`json:"metric"`
	TimeStamp int64			`json:"timestamp"`
	Value float64			`json:"value"`
	Tags map[string]string	`json:"tags"`
}

type responseExample struct {
	Message string	`json:"message"`
	Error 	string	`json:"error"`
}

func (mux *MyMux) sayHello(w http.ResponseWriter, r *http.Request) {
	if r.Method != "GET" {
		http.Error(w, "the method is not allowed！", http.StatusMethodNotAllowed)
		return
	}
	_, err:=  fmt.Fprintf(w, "Hello World!")
	fmt.Printf("在控制台输出Hello,World!\n")
	if err != nil{
		http.Error(w, "控制台打印出错1", http.StatusExpectationFailed)
		return
	}
}

func (mux *MyMux) sayHi(w http.ResponseWriter, r *http.Request){
	if r.Method != "POST"{
		http.Error(w, "the method is not allowed！", http.StatusMethodNotAllowed)
		return
	}
	_, err:=  fmt.Fprintf(w, "Hi World!")
	fmt.Printf("在控制台输出Hi,World!\n")
	if err != nil{
		http.Error(w, "控制台打印出错2", http.StatusExpectationFailed)
		return
	}
}

func (mux *MyMux) writeJsonToClient(w http.ResponseWriter, r *http.Request){

    response := make([]*responseExample,3)
    //初始化response的信息
    for index, _ := range response{
     	response[index] = &responseExample{
     		Message: "this is test message "+strconv.Itoa(index),
     		Error:"this is test error "+strconv.Itoa(index),
     	}
    }

     //解析go结构体变量为json数据
     jsonData, err:= json.Marshal(response)
     if err != nil{
		 log.Fatalf("JSON marshaling  failed: %s",err)
	 }
	 w.Header().Set("Content-Type","application/json")
     //打印到控制台
	 fmt.Printf("%s\n", jsonData)
     //打印到浏览器
	 _, _ = fmt.Fprintf(w, "%s\n", jsonData)
}

func (muc *MyMux) parseJsonFromClient(w http.ResponseWriter, r *http.Request){
	if r.Method != "POST"{
     	http.Error(w, "the method is not allowed", http.StatusMethodNotAllowed)
	}

	if r.Header.Get("Content-TyPe") != "application/json"{
		http.Error(w, "please set Encode method application/json", http.StatusBadRequest)
	}
    //流式解码器
	br := bufio.NewReader(r.Body)

	// 查看前1个字节
	f, err := br.Peek(1)
	if err != nil || len(f) != 1 {
		http.Error(w, "peek error: "+err.Error(), http.StatusBadRequest)
		return
	}
	// Peek to see if this is a JSON array.
	var multi bool
	switch f[0] {
	case '{':
		multi = false
	case '[':
		multi = true
	default:
		http.Error(w, "expected JSON array or hash", http.StatusBadRequest)
		return
	}

	dps := make([]point,1)
	//如果是多个对象{}组成的数组[],那么久解码到dps
	if dec := json.NewDecoder(br);multi{
		if err := dec.Decode(&dps); err!=nil{
			http.Error(w, "json array decode error", http.StatusBadRequest)
			return
		}
	}else{//否则，解码到dps[0]
		if err = dec.Decode(&dps[0]); err != nil {
			http.Error(w, "json object decode error", http.StatusBadRequest)
			return
		}
	}
   // fmt.Print(len(dps))
   // fmt.Print(dps)
	jsonData, err:= json.Marshal(dps)
	if err!= nil{
		log.Fatalf("JSON marshaling  failed: %s",err)
	}
	w.Header().Set("Content-Type","application/json")
	fmt.Printf("%s\n", jsonData)
	_, _ = fmt.Fprintf(w, "%s\n", jsonData)
	//_, _ = fmt.Fprint(w, jsonData)
}
//实现http.Handler这个接口的唯一方法
func (mux *MyMux) ServeHTTP(w http.ResponseWriter, r *http.Request){
	urlPath := r.URL.Path
	switch urlPath{
		case "/hello":
			mux.sayHello(w, r)
		case "/hi":
			mux.sayHi(w, r)
		case "/jsonPost":
			mux.parseJsonFromClient(w, r)
		case "/jsonGet":
			mux.writeJsonToClient(w, r)
		default:
		    http.Error(w, "没有此url路径", http.StatusBadRequest)
	}
}

func main(){
	   //实例化路由器Handler
	   mymux := &MyMux{}
	   //基于TCP服务监听8088端口
       ln, err := net.Listen("tcp", ":8088")
       if err != nil{
       		fmt.Printf("设置监听端口出错...")
	   }
       //调用http.Serve(l net.Listener, handler Handler)方法，启动监听
      err1 := http.Serve(ln, mymux)
      if err1 != nil{
      	fmt.Printf("启动监听出错")
	  }
}

在Goland工具中启动该程序，并在PostMan中测试