我尝试从web读取JSON数据,但代码返回空结果。我不确定我到底做错了什么。
package main
import "os"
import "fmt"
import "net/http"
import "io/ioutil"
import "encoding/json"
type Tracks struct {
Toptracks []Toptracks_info
}
type Toptracks_info struct {
Track []Track_info
Attr []Attr_info
}
type Track_info struct {
Name string
Duration string
Listeners string
Mbid string
Url string
Streamable []Streamable_info
Artist []Artist_info
Attr []Track_attr_info
}
type Attr_info struct {
Country string
Page string
PerPage string
TotalPages string
Total string
}
type Streamable_info struct {
Text string
Fulltrack string
}
type Artist_info struct {
Name string
Mbid string
Url string
}
type Track_attr_info struct {
Rank string
}
func get_content() {
// json data
url := "http://ws.audioscrobbler.com/2.0/?method=geo.gettoptracks&api_key=c1572082105bd40d247836b5c1819623&format=json&country=Netherlands"
res, err := http.Get(url)
if err != nil {
panic(err.Error())
}
body, err := ioutil.ReadAll(res.Body)
if err != nil {
panic(err.Error())
}
var data Tracks
json.Unmarshal(body, &data)
fmt.Printf("Results: %v\n", data)
os.Exit(0)
}
func main() {
get_content()
}
发布于 2013-06-18 06:10:32
您的问题是数据structs
中的切片声明(除了Track
,它们不应该是切片...)。在获取的json文件中,一些相当愚蠢的字段名使这一点变得更加复杂,这可以通过结构标签来修复,请参阅godoc。
下面的代码成功解析了json。如果你还有其他问题,请告诉我。
package main
import "fmt"
import "net/http"
import "io/ioutil"
import "encoding/json"
type Tracks struct {
Toptracks Toptracks_info
}
type Toptracks_info struct {
Track []Track_info
Attr Attr_info `json: "@attr"`
}
type Track_info struct {
Name string
Duration string
Listeners string
Mbid string
Url string
Streamable Streamable_info
Artist Artist_info
Attr Track_attr_info `json: "@attr"`
}
type Attr_info struct {
Country string
Page string
PerPage string
TotalPages string
Total string
}
type Streamable_info struct {
Text string `json: "#text"`
Fulltrack string
}
type Artist_info struct {
Name string
Mbid string
Url string
}
type Track_attr_info struct {
Rank string
}
func perror(err error) {
if err != nil {
panic(err)
}
}
func get_content() {
url := "http://ws.audioscrobbler.com/2.0/?method=geo.gettoptracks&api_key=c1572082105bd40d247836b5c1819623&format=json&country=Netherlands"
res, err := http.Get(url)
perror(err)
defer res.Body.Close()
decoder := json.NewDecoder(res.Body)
var data Tracks
err = decoder.Decode(&data)
if err != nil {
fmt.Printf("%T\n%s\n%#v\n",err, err, err)
switch v := err.(type){
case *json.SyntaxError:
fmt.Println(string(body[v.Offset-40:v.Offset]))
}
}
for i, track := range data.Toptracks.Track{
fmt.Printf("%d: %s %s\n", i, track.Artist.Name, track.Name)
}
}
func main() {
get_content()
}
发布于 2013-06-18 04:42:25
为了被json包使用,你需要在你的结构中使用大写的属性名。
大写属性名称为exported properties
。不会导出小写的特性名称。
您还需要按引用传递数据对象(&data
)。
package main
import "os"
import "fmt"
import "net/http"
import "io/ioutil"
import "encoding/json"
type tracks struct {
Toptracks []toptracks_info
}
type toptracks_info struct {
Track []track_info
Attr []attr_info
}
type track_info struct {
Name string
Duration string
Listeners string
Mbid string
Url string
Streamable []streamable_info
Artist []artist_info
Attr []track_attr_info
}
type attr_info struct {
Country string
Page string
PerPage string
TotalPages string
Total string
}
type streamable_info struct {
Text string
Fulltrack string
}
type artist_info struct {
Name string
Mbid string
Url string
}
type track_attr_info struct {
Rank string
}
func get_content() {
// json data
url := "http://ws.audioscrobbler.com/2.0/?method=geo.gettoptracks&api_key=c1572082105bd40d247836b5c1819623&format=json&country=Netherlands"
res, err := http.Get(url)
if err != nil {
panic(err.Error())
}
body, err := ioutil.ReadAll(res.Body)
if err != nil {
panic(err.Error())
}
var data tracks
json.Unmarshal(body, &data)
fmt.Printf("Results: %v\n", data)
os.Exit(0)
}
func main() {
get_content()
}
发布于 2013-06-18 07:41:18
从json.Unmarshal
(到var data interface{}
中)的结果与Go类型和变量声明不直接匹配。例如,
package main
import (
"encoding/json"
"fmt"
"io/ioutil"
"net/http"
"os"
)
type Tracks struct {
Toptracks []Toptracks_info
}
type Toptracks_info struct {
Track []Track_info
Attr []Attr_info
}
type Track_info struct {
Name string
Duration string
Listeners string
Mbid string
Url string
Streamable []Streamable_info
Artist []Artist_info
Attr []Track_attr_info
}
type Attr_info struct {
Country string
Page string
PerPage string
TotalPages string
Total string
}
type Streamable_info struct {
Text string
Fulltrack string
}
type Artist_info struct {
Name string
Mbid string
Url string
}
type Track_attr_info struct {
Rank string
}
func get_content() {
// json data
url := "http://ws.audioscrobbler.com/2.0/?method=geo.gettoptracks&api_key=c1572082105bd40d247836b5c1819623&format=json&country=Netherlands"
url += "&limit=1" // limit data for testing
res, err := http.Get(url)
if err != nil {
panic(err.Error())
}
body, err := ioutil.ReadAll(res.Body)
if err != nil {
panic(err.Error())
}
var data interface{} // TopTracks
err = json.Unmarshal(body, &data)
if err != nil {
panic(err.Error())
}
fmt.Printf("Results: %v\n", data)
os.Exit(0)
}
func main() {
get_content()
}
输出:
Results: map[toptracks:map[track:map[name:Get Lucky (feat. Pharrell Williams) listeners:1863 url:http://www.last.fm/music/Daft+Punk/_/Get+Lucky+(feat.+Pharrell+Williams) artist:map[name:Daft Punk mbid:056e4f3e-d505-4dad-8ec1-d04f521cbb56 url:http://www.last.fm/music/Daft+Punk] image:[map[#text:http://userserve-ak.last.fm/serve/34s/88137413.png size:small] map[#text:http://userserve-ak.last.fm/serve/64s/88137413.png size:medium] map[#text:http://userserve-ak.last.fm/serve/126/88137413.png size:large] map[#text:http://userserve-ak.last.fm/serve/300x300/88137413.png size:extralarge]] @attr:map[rank:1] duration:369 mbid: streamable:map[#text:1 fulltrack:0]] @attr:map[country:Netherlands page:1 perPage:1 totalPages:500 total:500]]]
https://stackoverflow.com/questions/17156371
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