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)
}

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)
 }
} 
}