goでjson apiを叩く

goでjson apiを叩くサンプル(Decoderを使ったバージョンも追加)

json_sample.go

package main

import (
  "net/http"
  "fmt"
  "log"
  "encoding/json"
  "io/ioutil"
  "flag"
)

type JsonTestDate struct {
  Time string `json:"time"`
  Msec int64  `json:"milliseconds_since_epoch"`
  Date string `json:"date"`
}

func main(){
  useDecoder := false
  flag.BoolVar(&useDecoder, "decoder", false, "use json decoder")
  flag.Parse()

  res, err := http.Get("http://date.jsontest.com/")
  if err != nil {
    log.Fatal(err)
  }
  defer res.Body.Close()
  if res.StatusCode != 200 {
    fmt.Println("StatusCode=%d", res.StatusCode)
    return
  }
  //Dump response status line
  fmt.Printf("======Status line======\n")
  fmt.Printf("%s %s\n", res.Proto, res.Status)

  //Dump response header
  fmt.Printf("======Header======\n")
  for k, v := range res.Header {
    fmt.Printf("%s:%s\n", k, v)    
  }

  var d JsonTestDate
  if !useDecoder {
    //Dump response body (use json.Unmarshal)
    fmt.Printf("======Body (use json.Unmarshal)======\n")
    body, err := ioutil.ReadAll(res.Body)
    if err != nil {
      log.Fatal(err)    
    }

    err = json.Unmarshal(body, &d)
    if err != nil {
      log.Fatal(err)    
    }
  } else {
    //Dump response body (use Decoder)
    fmt.Printf("======Body(use json.Decoder)======\n")
    decoder := json.NewDecoder(res.Body)
    err = decoder.Decode(&d)
    if err != nil {
      log.Fatal(err)    
    }
  }
  fmt.Printf("%v\n", d)
}

➜  golan go run json_sample.go -decoder=1
======Status line======
HTTP/1.1 200 OK
======Header======
Access-Control-Allow-Origin:[*]
Content-Type:[application/json; charset=ISO-8859-1]
Date:[Fri, 10 Jun 2016 14:28:38 GMT]
Server:[Google Frontend]
Content-Length:[100]
======Body(use json.Decoder)======
{02:28:38 PM 1465568918612 06-10-2016}
➜  golan go run json_sample.go
======Status line======
HTTP/1.1 200 OK
======Header======
Access-Control-Allow-Origin:[*]
Content-Type:[application/json; charset=ISO-8859-1]
Date:[Fri, 10 Jun 2016 14:28:43 GMT]
Server:[Google Frontend]
Content-Length:[100]
======Body (use json.Unmarshal)======
{02:28:43 PM 1465568923974 06-10-2016}