golang 11. pair reflect struct_tag json

pair1.go

package main

import "fmt"

func main() {

	var a string
	//pair<statictype:string, value:"aceld">
	a = "aceld"

	//pair<type:string, value:"aceld">
	var allType interface{}
	allType = a

	str, _ := allType.(string)
	fmt.Println(str)
}

pair2.go

package main

import (
	"fmt"
	"io"
	"os"
)

func main() {
	//tty: pair<type:*os.File, value:"/dev/tty"文件描述符>
	tty, err := os.OpenFile("/dev/tty", os.O_RDWR, 0)

	if err != nil {
		fmt.Println("open file error", err)
		return
	}

	//r: pair<type:  , value:>
	var r io.Reader
	//r: pair<type:*os.File, value:"/dev/tty"文件描述符>
	r = tty

	//w: pair<type:  , value:>
	var w io.Writer
	//w: pair<type:*os.File, value:"/dev/tty"文件描述符>
	w = r.(io.Writer)

	w.Write([]byte("HELLO THIS is A TEST!!!\n"))
}

pair3.go

package main

import "fmt"

type Reader interface {
	ReadBook()
}

type Writer interface {
	WriteBook()
}

//具体类型
type Book struct {
}

func (this *Book) ReadBook() {
	fmt.Println("Read a Book")
}

func (this *Book) WriteBook() {
	fmt.Println("Write a Book")
}

func main() {
	//b: pair<type:Book, value:book{}地址>
	b := &Book{}

	//r: pair<type:, value:>
	var r Reader
	//r: pair<type:Book, value:book{}地址>
	r = b

	r.ReadBook()

	var w Writer
	//r: pair<type:Book, value:book{}地址>
	w = r.(Writer) //此处的断言为什么会成功？ 因为w r 具体的type是一致

	w.WriteBook()
}

reflect1.go

package main

import (
	"fmt"
	"reflect"
)

func reflectNum(arg interface{}) {
	fmt.Println("type : ", reflect.TypeOf(arg))
	fmt.Println("value : ", reflect.ValueOf(arg))
}

func main() {
	var num float64 = 1.2345

	reflectNum(num)
}

reflect2.go

package main

import (
	"fmt"
	"reflect"
)

type User struct {
	Id   int
	Name string
	Age  int
}

func (this User) Call() {
	fmt.Println("user is called ..")
	fmt.Printf("%v\n", this)
}

func main() {
	user := User{1, "Aceld", 18}

	DoFiledAndMethod(user)
}

func DoFiledAndMethod(input interface{}) {
	//获取input的type
	inputType := reflect.TypeOf(input)
	fmt.Println("inputType is :", inputType.Name())

	//获取input的value
	inputValue := reflect.ValueOf(input)
	fmt.Println("inputValue is:", inputValue)

	//通过type 获取里面的字段
	//1. 获取interface的reflect.Type，通过Type得到NumField ,进行遍历
	//2. 得到每个field，数据类型
	//3. 通过filed有一个Interface()方法等到 对应的value
	for i := 0; i < inputType.NumField(); i++ {
		field := inputType.Field(i)
		value := inputValue.Field(i).Interface()

		fmt.Printf("%s: %v = %v\n", field.Name, field.Type, value)
	}

	//通过type 获取里面的方法,调用
	for i := 0; i < inputType.NumMethod(); i++ {
		m := inputType.Method(i)
		fmt.Printf("%s: %v\n", m.Name, m.Type)
	}

}
/*
inputType is : User
inputValue is: {1 Aceld 18}
Id: int = 1
Name: string = Aceld
Age: int = 18
Call: func(main.User)
*/

structtag.go

package main

import (
	"fmt"
	"reflect"
)

type resume struct {
	Name string `info:"name" doc:"我的名字"`
	Sex  string `info:"sex"`
}

func findTag(str interface{}) {
	t := reflect.TypeOf(str).Elem()

	for i := 0; i < t.NumField(); i++ {
		taginfo := t.Field(i).Tag.Get("info")
		tagdoc := t.Field(i).Tag.Get("doc")
		fmt.Println("info: ", taginfo, " doc: ", tagdoc)
	}
}

func main() {
	var re resume

	findTag(&re)

}

json.go

package main

import (
	"encoding/json"
	"fmt"
)

type Movie struct {
	Title  string   `json:"title"`
	Year   int      `json:"year"`
	Price  int      `json:"rmb"`
	Actors []string `json:"actors"`
}

func main() {
	movie := Movie{"喜剧之王", 2000, 10, []string{"xingye", "zhangbozhi"}}

	//编码的过程  结构体---> json
	jsonStr, err := json.Marshal(movie)
	if err != nil {
		fmt.Println("json marshal error", err)
		return
	}

	fmt.Printf("jsonStr = %s\n", jsonStr)

	//解码的过程 jsonstr ---> 结构体
	//jsonStr = {"title":"喜剧之王","year":2000,"rmb":10,"actors":["xingye","zhangbozhi"]}
	myMovie := Movie{}
	err = json.Unmarshal(jsonStr, &myMovie)
	if err != nil {
		fmt.Println("json unmarshal error ", err)
		return
	}

	fmt.Printf("%v\n", myMovie)
}