使用golang解析JSON HTTP响应

Question

我试图从我的以下curl输出中获得说"ip"的值:

{  
  "type":"example",
  "data":{  
    "name":"abc",
    "labels":{  
      "key":"value"
    }
  },
  "subsets":[  
    {  
      "addresses":[  
        {  
          "ip":"192.168.103.178"
        }
      ],
      "ports":[  
        {  
          "port":80
        }
      ]
    }
  ]
}

我在互联网上发现很多例子来解析curl请求的json输出,我写了下面的代码,但这似乎没有给我回复说"ip"的值

package main

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

type svc struct {
    Ip string `json:"ip"`
}

func main() {

url := "http://myurl.com"

testClient := http.Client{
    Timeout: time.Second * 2, // Maximum of 2 secs
}

req, err := http.NewRequest(http.MethodGet, url, nil)
if err != nil {
    log.Fatal(err)
}


res, getErr := testClient.Do(req)
if getErr != nil {
    log.Fatal(getErr)
}

body, readErr := ioutil.ReadAll(res.Body)
if readErr != nil {
    log.Fatal(readErr)
}

svc1 := svc{}
jsonErr := json.Unmarshal(body, &svc1)
if jsonErr != nil {
    log.Fatal(jsonErr)
}

fmt.Println(svc1.Ip)
}

我很感激,如果有人能提供我需要添加到我的代码中的提示,以获得说"ip"的值.

Answer 1

您可以创建结构来模仿您的json结构,然后解码您的json.

package main

import (
    "bytes"
    "encoding/json"
    "fmt"
    "log"
)

type Example struct {
    Type    string   `json:"type,omitempty"`
    Subsets []Subset `json:"subsets,omitempty"`
}

type Subset struct {
    Addresses []Address `json:"addresses,omitempty"`
}

type Address struct {
    IP string `json:"IP,omitempty"`
}

    func main() {

    m := []byte(`{"type":"example","data": {"name": "abc","labels": {"key": "value"}},"subsets": [{"addresses": [{"ip": "192.168.103.178"}],"ports": [{"port": 80}]}]}`)

    r := bytes.NewReader(m)
    decoder := json.NewDecoder(r)

    val := &Example{}
    err := decoder.Decode(val)

    if err != nil {
        log.Fatal(err)
    }

    // If you want to read a response body
    // decoder := json.NewDecoder(res.Body)
    // err := decoder.Decode(val)

    // Subsets is a slice so you must loop over it
    for _, s := range val.Subsets {
        // within Subsets, address is also a slice
        // then you can access each IP from type Address
        for _, a := range s.Addresses {
            fmt.Println(a.IP)
        }
    }

}

输出将是: 192.168.103.178

通过将其解码为结构,您可以遍历任何切片,而不是将自己限制为一个IP

这里的例子:

https://play.golang.org/p/sWA9qBWljA

Answer 2

一种方法是将 JSON 解组为 a map，例如（假设jsData包含 JSON 字符串）

obj := map[string]interface{}{}
if err := json.Unmarshal([]byte(jsData), &obj); err != nil {
    log.Fatal(err)
}

接下来，实现一个函数，用于从映射中递归搜索与键关联的值，例如

func find(obj interface{}, key string) (interface{}, bool) {
    //if the argument is not a map, ignore it
    mobj, ok := obj.(map[string]interface{})
    if !ok {
        return nil, false
    }

    for k, v := range mobj {
        //key match, return value
        if k == key {
            return v, true
        }

        //if the value is a map, search recursively
        if m, ok := v.(map[string]interface{}); ok {
            if res, ok := find(m, key); ok {
                return res, true
            }
        }
        //if the value is an array, search recursively 
        //from each element
        if va, ok := v.([]interface{}); ok {
            for _, a := range va {
                if res, ok := find(a, key); ok {
                    return res,true
                }
            }
        }
    }

    //element not found
    return nil,false
}

请注意，上述函数返回一个interface{}. 您需要将其转换为适当的类型，例如使用类型开关：

if ip, ok := find(obj, "ip"); ok {
    switch v := ip.(type) {
    case string:
        fmt.Printf("IP is a string -> %s\n", v)
    case fmt.Stringer:
        fmt.Printf("IP implements stringer interface -> %s\n", v.String())
    case int:

    default:
        fmt.Printf("IP = %v, ok = %v\n", ip, ok)
    }
}

可以在https://play.golang.org/p/O5NUi4J0iR找到一个工作示例