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This article introduces the knowledge of "what does go language reflection refer to". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

Interpretation of reflection

Reflection in Go is quite different from other languages. Emission in Golang mainly involves two basic concepts, Type and Value, which are also the two most important types in the reflect package of the Go language package.

By reflecting all interfaces in Golang, you can get an information structure containing Type and Value. As the name implies, Type mainly expresses the type information of the reflected variable itself, while Value is the information of the instance of the variable itself.

The role of reflection

Reflection in Golang has two main functions, namely, getting type information and getting value types.

With reflection, we can:

The encapsulation of dynamic analytic functions. Reflection acquisition data type

Syntax:

Reflect.TypeOf (x)

Function:

Get data type

Usage:

Package main

Import (

"fmt"

"reflect"

)

Func main () {

Var x = 3.4

Var str = "Hello World"

Fmt.Println ("x type =", reflect.TypeOf (x))

Fmt.Println ("str type =", reflect.TypeOf (str))

} reflection to get Type

Syntax:

Reflect.TypeOf (varname)

Function:

You can get the corresponding value of this variable.

Usage:

Package main

Import (

"fmt"

"reflect"

)

Func main () {

Var x = 1024

Var str = "Hello World"

Fmt.Println ("x type =", reflect.TypeOf (x))

Fmt.Println ("str type =", reflect.TypeOf (str))

}

Reflection acquisition Type

Syntax:

Reflect.TypeOf (varname) .Kind ()

Function:

Use reflect.TypeOf to pass in the variable we want to get, that is, we can get the type of the variable, and use the Kind method to get the details of the type.

Usage:

Package main

Import (

"fmt"

"reflect"

)

Func main () {

Var x = 1024

Var str = "Hello World"

TypeX: = reflect.TypeOf (x)

TypeStr: = reflect.TypeOf (str)

TypexKind: = typeX.Kind ()

TypeStrKind: = typeStr.Kind ()

Fmt.Println ("x type =", typeX, ", Kind =", typexKind)

Fmt.Println ("str type =", typeStr, ", Kind =", typeStrKind)

} reflection gets variable value information

Syntax:

Reflect.ValueOf (varname)

Function:

Using reflect.ValueOf to pass in the variable we want to get, we can get the value information of the variable.

Usage:

Package main

Import (

"fmt"

"reflect"

)

Func main () {

Var x = 1024

Var str = "Hello World"

ValueX: = reflect.ValueOf (x)

ValueStr: = reflect.ValueOf (str)

Fmt.Println ("valueX =", valueX)

Fmt.Println ("valueStr =", valueStr)

} reflection gets the pointer pointed to by the variable

Syntax:

Reflect.ValueOf (varname) .Elem ()

Function:

Using reflect.ValueOf to pass in the variable we want to get, we can get the value information of the variable.

Usage:

Package main

Import (

"fmt"

"reflect"

)

Func main () {

Var x = 1024

Var str = "Hello World"

ValueX: = reflect.ValueOf (x)

ValueStr: = reflect.ValueOf (str)

Fmt.Println ("valueX =", valueX)

Fmt.Println ("valueStr =", valueStr)

ValueElemX: = valueX.Elem ()

ValueElemStr: = valueStr.Elem ()

Fmt.Println ("valueElemX =", valueElemX)

Fmt.Println ("valueElemStr =", valueElemStr)

} reflection calls the structure method

Syntax:

PersonValue: = reflect.ValueOf (p)

InfoFunc: = personValue.MethodByName ("Info")

InfoFunc.Call ([] reflect.Value {})

Function:

Get the value information of the structure through reflect.ValueOf, and then use the MethodByName of the structure value information to obtain the structure. Finally, you can use the Call method to call the structure.

Usage:

Import (

"fmt"

"reflect"

)

Type Student struct {

Name string

Age int

Score float64

}

Func (s Student) Info () {

Fmt.Println ("Name =", s.Name, "Age =", s.Age, "Score =", s.Score)

}

Func main () {

Var p = Student {

Name: "Jim"

Age:10

Score:99

}

PersonValue: = reflect.ValueOf (p)

InfoFunc: = personValue.MethodByName ("Info")

InfoFunc.Call ([] reflect.Value {})

} combined use

The following code uses TypeOf to deal with the array and time type values contained in the structure. It can be used as a general reflection method.

Func reflect (o interface {}) error {

Re: = reflect.TypeOf (o) .Elem ()

Rv: = reflect.ValueOf (o) .Elem ()

/ / determine whether it is a structure or not

If re.Kind () = = reflect.Struct {

For I: = 0; I < re.NumField (); iTunes + {

F: = re.Field (I)

Name: = f.Name

Fmt.Printf ("field name% v:", name)

/ / get the value of one of the fields in the structure

V: = rv.FieldByName (name)

If v.Kind () = = reflect.Struct {

/ / processing time type

If v.Type () .ConvertibleTo (reflect.TypeOf (time.Time {})) {

Fmt.Printf ("field name:% v type of time", name)

Continue

}

/ / determine whether it is empty or not

If! v.IsNil () {

Fmt.Printf ("field name:% v is empty", name)

Continue

}

/ / TODO there is no business logic to supplement here

}

/ / handle array types

If v.Kind () = = reflect.Slice {

For j: = 0; j < v.Len (); Jake + {

/ / determine whether the objects in the array are pointer types

If reflect.TypeOf (v.Index (j). Interface ()) .Kind () = = reflect.Ptr {

Fmt.Printf ("field name:% v type of Ptr", name)

Continue

}

}

}

}

}

Return nil

}

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