如何从 http.Get 获取 JSON 响应 [英] How to get JSON response from http.Get

问题描述

我正在尝试从网络读取 JSON 数据，但该代码返回空结果.我不确定我在这里做错了什么.

I'm trying read JSON data from web, but that code returns empty result. I'm not sure what I'm doing wrong here.

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
", data)
    os.Exit(0)
}

func main() {
    get_content()
}

推荐答案

理想的方式是不使用 ioutil.ReadAll，而是在阅读器上使用解码器直接地.这是一个很好的函数，它获取 url 并将其响应解码到 target 结构上.

The ideal way is not to use ioutil.ReadAll, but rather use a decoder on the reader directly. Here's a nice function that gets a url and decodes its response onto a target structure.

var myClient = &http.Client{Timeout: 10 * time.Second}

func getJson(url string, target interface{}) error {
    r, err := myClient.Get(url)
    if err != nil {
        return err
    }
    defer r.Body.Close()

    return json.NewDecoder(r.Body).Decode(target)
}

示例使用:

type Foo struct {
    Bar string
}

func main() {
    foo1 := new(Foo) // or &Foo{}
    getJson("http://example.com", foo1)
    println(foo1.Bar)

    // alternately:

    foo2 := Foo{}
    getJson("http://example.com", &foo2)
    println(foo2.Bar)
}

你不应该在生产中使用默认的 *http.Client 结构，因为这个答案最初是这样展示的！(这就是 http.Get/etc 调用的内容).原因是默认客户端没有设置超时；如果远程服务器没有响应，那你的日子就不好过了.

You should not be using the default *http.Client structure in production as this answer originally demonstrated! (Which is what http.Get/etc call to). The reason is that the default client has no timeout set; if the remote server is unresponsive, you're going to have a bad day.

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