json - 深度相等 : Why does an unmarshalled map return DeepEqual() results differently than a seemingly identical literal

Question

我不明白如何比较未编码的 JSON。示例:

package main

import (
    "fmt"
    "reflect"
    "encoding/json"
)

func main() {
    a := map[string]interface{} {"foo": 1, "bar": 2}
    b := map[string]interface{} {"bar": 2, "foo": 1}
    fmt.Printf("Literal B is %v, DeepEqual is %v\n", b, reflect.DeepEqual(a, b))

    err := json.Unmarshal([]byte(`{"bar": 2, "foo": 1}`), &b)
    if err != nil {
        panic("Could not unmarshal")
    }
    fmt.Printf("Umarshalled B is %v, DeepEqual is %v\n", b, reflect.DeepEqual(a, b))
}

打印

文字 B 是 map[bar:2 foo:1]，DeepEqual 是 true

Umarshalled B 是 map[bar:2 foo:1]，DeepEqual 是false

从文字初始化的 B 和 JSON 解码后的 B 有什么不同？

Answer 1

这回答了你的问题:

fmt.Printf("%T\n", b["foo"]) // Prints "float64" after unmarshaling.

JSON 数字是 64 位 float ，而您的原始 map 值是整数。来自docs :

To unmarshal JSON into an interface value, Unmarshal stores one of these in the interface value:

bool, for JSON booleans
float64, for JSON numbers
string, for JSON strings
[]interface{}, for JSON arrays
map[string]interface{}, for JSON objects
nil for JSON null