Go-json解码到结构体-踩坑

package main

import (
    "encoding/json"
    "fmt"
)

type User struct {
    Name string `json:"name"`
}

func main() {
    var u User
    fmt.Printf("u=%+v, &u=%p\n", u, &u) //output: u={Name:}, &u=0xc00003e230
    json.Unmarshal([]byte(`{"name":"polaris"}`), &u)
    fmt.Printf("u.Name=%+v\n", u.Name) //output: u.Name=polaris

    //var u1 *User
    //fmt.Printf("u1=%+v, &u1=%p\n", u1, &u1) //output: u1=<nil>, &u1=0xc00007a028
    //json.Unmarshal([]byte(`{"name":"polaris"}`), u1)
    ////以上会直接报错：panic: runtime error: invalid memory address or nil pointer dereference
    //fmt.Printf("u1.Name=%+v\n", u1.Name)

    var u2 *User
    fmt.Printf("u2=%+v, &u2=%p\n", u2, &u2) //output: u2=<nil>, &u2=0xc00007a028
    json.Unmarshal([]byte(`{"name":"polaris"}`), &u2)
    fmt.Printf("u2.Name=%+v\n", u2.Name) //正常打印出u2.Name=polaris

    /**
    总结：
        json.Unmarshal()第二个参数必须传入一个有内存地址的变量
    */
}