本文的是一篇入门文章，通过一个简单的例子介绍Golang的Web编程主要用到的技术。

文章结构包括：

1. Client-Get 请求
   
2. Client-Post请求
   
3. Server 处理 Get 和 Post 数据

在数据的封装中，我们部分采用了json，因而本文也涉及到Golang中json的编码和解码。

一、Client-Get

package main

import (
        "fmt"
        "net/url"
        "net/http"
        "io/IoUtil"
        "log"
)

func main() {
        u,_ := url.Parse("http://localhost:9001/xiaoyue")
        q := u.Query()
        q.Set("username","user")
        q.Set("password","passwd")
        u.RawQuery = q.Encode()
        res,err := http.Get(u.String());
       if err != nil { 
              log.Fatal(err) return 
        }
       result,err := IoUtil.ReadAll(res.Body) 
        res.Body.Close() 
        if err != nil { 
              log.Fatal(err) return 
        } 
        fmt.Printf("%s",result)
}

二、Client-Post

package main

import (
        "fmt"
        "net/url"
        "net/http"
        "io/IoUtil"
        "log"
        "bytes"
        "encoding/json"
)

type Server struct {
        ServerName string
        ServerIP   string
}

type Serverslice struct {
        Servers []Server
        ServersID  string
}


func main() {

        var s Serverslice

       var newServer Server;
        newServer.ServerName = "Guangzhou_VPN";
        newServer.ServerIP = "127.0.0.1"       
        s.Servers = append(s.Servers,newServer)

       s.Servers = append(s.Servers,Server{ServerName: "Shanghai_VPN",ServerIP: "127.0.0.2"})
        s.Servers = append(s.Servers,Server{ServerName: "Beijing_VPN",ServerIP: "127.0.0.3"})
 
 s.ServersID = "team1"

 b,err := json.Marshal(s)
 if err != nil {
 fmt.Println("json err:",err)
 }

 body := bytes.NewBuffer([]byte(b))
 res,err := http.Post("http://localhost:9001/xiaoyue","application/json;charset=utf-8",body)
 if err != nil {
 log.Fatal(err)
 return
 }
 result,err := IoUtil.ReadAll(res.Body)
 res.Body.Close()
 if err != nil {
 log.Fatal(err)
 return
 }
 fmt.Printf("%s",result)
}

三、Server

package main

import (
        "fmt"
        "net/http"
        "strings"
        "html"
        "io/IoUtil"
        "encoding/json"
)

type Server struct {
        ServerName string
        ServerIP   string
}

type Serverslice struct {
        Servers []Server
        ServersID  string
}

func main() {
       http.HandleFunc("/",handler) 
        http.ListenAndServe(":9001",nil)
}

func handler(w http.ResponseWriter,r *http.Request) { 
        r.ParseForm() //解析参数，默认是不会解析的 
        fmt.Fprintf(w,"Hi,I love you %s",html.EscapeString(r.URL.Path[1:]))
       if r.Method == "GET" {
               fmt.Println("method:",r.Method) //获取请求的方法 

                fmt.Println("username",r.Form["username"]) 
                fmt.Println("password",r.Form["password"]) 

                for k,v := range r.Form {
                       fmt.Print("key:",k,"; ")
                       fmt.Println("val:",strings.Join(v,""))
               }
        } else if r.Method == "POST" {
               result,_:= IoUtil.ReadAll(r.Body)
               r.Body.Close()
               fmt.Printf("%s\n",result)

                //未知类型的推荐处理方法

               var f interface{}
               json.Unmarshal(result,&f) 
                m := f.(map[string]interface{})
               for k,v := range m {
                       switch vv := v.(type) {
                               case string:
                                       fmt.Println(k,"is string",vv)
                               case int:
                                       fmt.Println(k,"is int",vv)
                               case float64:
                                       fmt.Println(k,"is float64",vv)
                               case []interface{}:
                                       fmt.Println(k,"is an array:")
                                       for i,u := range vv {
                                               fmt.Println(i,u)
                                       }
                               default:
                                       fmt.Println(k,"is of a type I don't know how to handle") 
                         }
                 }

                 //结构已知，解析到结构体

                var s Serverslice;
             json.Unmarshal([]byte(result),&s)

        fmt.Println(s.ServersID);
 
         for i:=0; i<len(s.Servers); i++ {
          fmt.Println(s.Servers[i].ServerName)
         fmt.Println(s.Servers[i].ServerIP)
         }
       } 
}