reflect
最后更新于：2022-04-02 02:45:39
[TOC]
## reflect
### type 所有的类型
```
const (
Invalid Kind = iota
Bool
Int
Int8
Int16
Int32
Int64
Uint
Uint8
Uint16
Uint32
Uint64
Uintptr
Float32
Float64
Complex64
Complex128
Array
Chan
Func
Interface
Map
Ptr
Slice
String
Struct
UnsafePointer
)
```
### reflect.ValueOf
```
type Value
func ValueOf(i interface{}) Value
func Zero(typ Type) Value
func New(typ Type) Value
func NewAt(typ Type, p unsafe.Pointer) Value
func Indirect(v Value) Value
func MakeSlice(typ Type, len, cap int) Value
func MakeMap(typ Type) Value
func MakeChan(typ Type, buffer int) Value
func MakeFunc(typ Type, fn func(args []Value) (results []Value)) Value
func Append(s Value, x ...Value) Value
func AppendSlice(s, t Value) Value
func (v Value) IsValid() bool
func (v Value) IsNil() bool
func (v Value) Kind() Kind
func (v Value) Type() Type
func (v Value) Convert(t Type) Value
func (v Value) Elem() Value
func (v Value) Bool() bool
func (v Value) Int() int64
func (v Value) OverflowInt(x int64) bool
func (v Value) Uint() uint64
func (v Value) OverflowUint(x uint64) bool
func (v Value) Float() float64
func (v Value) OverflowFloat(x float64) bool
func (v Value) Complex() complex128
func (v Value) OverflowComplex(x complex128) bool
func (v Value) Bytes() []byte
func (v Value) String() string
func (v Value) Pointer() uintptr
func (v Value) InterfaceData() [2]uintptr
func (v Value) Slice(i, j int) Value
func (v Value) Slice3(i, j, k int) Value
func (v Value) Cap() int
func (v Value) Len() int
func (v Value) Index(i int) Value
func (v Value) MapIndex(key Value) Value
func (v Value) MapKeys() []Value
func (v Value) NumField() int
func (v Value) Field(i int) Value
func (v Value) FieldByIndex(index []int) Value
func (v Value) FieldByName(name string) Value
func (v Value) FieldByNameFunc(match func(string) bool) Value
func (v Value) Recv() (x Value, ok bool)
func (v Value) TryRecv() (x Value, ok bool)
func (v Value) Send(x Value)
func (v Value) TrySend(x Value) bool
func (v Value) Close()
func (v Value) Call(in []Value) []Value
func (v Value) CallSlice(in []Value) []Value
func (v Value) NumMethod() int
func (v Value) Method(i int) Value
func (v Value) MethodByName(name string) Value
func (v Value) CanAddr() bool
func (v Value) Addr() Value
func (v Value) UnsafeAddr() uintptr
func (v Value) CanInterface() bool
func (v Value) Interface() (i interface{})
func (v Value) CanSet() bool
func (v Value) SetBool(x bool)
func (v Value) SetInt(x int64)
func (v Value) SetUint(x uint64)
func (v Value) SetFloat(x float64)
func (v Value) SetComplex(x complex128)
func (v Value) SetBytes(x []byte)
func (v Value) SetString(x string)
func (v Value) SetPointer(x unsafe.Pointer)
func (v Value) SetCap(n int)
func (v Value) SetLen(n int)
func (v Value) SetMapIndex(key, val Value)
func (v Value) Set(x Value)
```
### Type
```
type Type
func ArrayOf(count int, elem Type) Type
func ChanOf(dir ChanDir, t Type) Type
func FuncOf(in, out []Type, variadic bool) Type
func MapOf(key, elem Type) Type
func PtrTo(t Type) Type
func SliceOf(t Type) Type
func StructOf(fields []StructField) Type
func TypeOf(i interface{}) Type
```
## 实例
### reflect.ValueOf 查看反射类型
```
for _, v := range []interface{}{"hi", 42, func() {}} {
switch v := reflect.ValueOf(v); v.Kind() {
case reflect.String:
fmt.Println(v.String())
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
fmt.Println(v.Int())
default:
fmt.Printf("unhandled kind %s", v.Kind())
}
}
// Output:
// hi
// 42
// unhandled kind func
```
### reflect.TypeOf 查看tag 标签
```
type S struct {
F string `species:"gopher" color:"blue"`
}
var s S
of := reflect.TypeOf(s)
fmt.Printf("%+v\n", of.Field(0).Tag.Get("species")) // gopher
fmt.Printf("%+v\n", of.Field(0).Tag.Get("color")) // blue
```
### Elem 当传入指针时,获取类型
```
func main() {
type Admin struct {
username string `demo:"user" type:"name"`
title string
}
a:=Admin{
username: "123",
title: "22",
}
demo1(a)
demo2(&a)
}
func demo1(i interface{}) {
of := reflect.ValueOf(i)
fmt.Printf("%+v\n", of.Field(0).String())
}
func demo2(i interface{}) {
of := reflect.ValueOf(i).Elem()
fmt.Printf("%+v\n", of.Field(0).String())
}
```
### Set 赋值
```
type T struct {
Age int
Name string
Children []int
}
// 初始化测试用例
t := T{12, "someone-life", nil}
//var t T
s := reflect.ValueOf(&t).Elem() // 反射获取测试对象对应的struct枚举类型fmt.Println(s.NumField()) //3
log.Printf("%v",s.NumField()) //3
s.Field(1).SetString("ccc")
s.FieldByName("Age").SetInt(123)
sliceValue := reflect.ValueOf([]int{1, 2, 3})
s.FieldByName("Children").Set(sliceValue) // 使用字段名称get，并赋值。赋值类型必须为reflect.Value
fmt.Printf("%+v\n", s) //{Age:123 Name:ccc Children:[1 2 3]}
```
### MakeFunc 泛型函数
```
var intSwap func(int, int) (int, int)
var floatSwap func(float64, float64) (float64, float64)
var swap = func(in []reflect.Value) []reflect.Value {
return []reflect.Value{in[1], in[0]}
}
func makeSwap(fptr interface{}) {
fn := reflect.ValueOf(fptr).Elem()
v := reflect.MakeFunc(fn.Type(), swap)
fn.Set(v)
}
func init() {
makeSwap(&intSwap)
makeSwap(&floatSwap)
}
func main() {
fmt.Println(intSwap(0, 1)) // 1 0
fmt.Println(floatSwap(2.72, 3.14)) // 3.14 2.72
}
```
### reflect.DeepEqua` 可比较连个 interface 是否相等
```
equal := reflect.DeepEqual([]string{"13"}, []string{"123"})
```
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