package main

import (
  "encoding/json"
  "fmt"
)

func main() {
    jsonStr := []byte(`{"uin":1589276509,"feedID":10000,"videos":[{"picture":"http://qqpublic.qpic.cn/avatar.jpg","duration":"839"}]}`)
    var jsonMap map[string]interface{}
    if err := json.Unmarshal(jsonStr, &jsonMap); err!=nil {
      fmt.Printf("json decode failed, err=%v", err)
      return
    }
    value, ok:=jsonMap["videos"]
    fmt.Printf("value=%#v\n", value)
    if ok {
        sliceValue, ok := value.([]interface{})
        if ok {
            mapValue, ok := sliceValue[0].(map[string]interface{})
            if ok {
                duration, ok := mapValue["duration"]
                if ok {
                    fmt.Printf("d=%v,type=%T\n",duration,duration)
                }
            }
        }
    }
}

package main

import (
  "encoding/json"
  "fmt"
)

type Stu struct {
  Name string `json:"name"`
  Age  int
  sex  string
  Class *Class `json:"class"`
}

type Class struct {
  Name string
  Grade int
}

func main() {
//实例化一个数据结构，用于生成json字符串
  stu := Stu{
    Name: "张三",
    Age: 18,
    sex: "男",
  }

  //指针变量
  cla := new(Class)
  cla.Name = "1班"
  cla.Grade = 3
  stu.Class=cla

  //Marshal失败时err!=nil
  jsonStu, err := json.Marshal(stu)
  if err != nil {
    fmt.Println("生成json字符串错误")
  }

  //jsonStu是[]byte类型，转化成string类型便于查看
  fmt.Println(string(jsonStu))
}