结构方法：
方法根据传入的参数的不同，又分为：值传递 和 指针传递。两者的效果就是：值传递不可改变值，指针传递可以改变值。
- 值传递的适用于取值
- 指针传递适用于更改字段的值
type Response struct {
Code int
Result []byte
Headers map[string]string
}
func (r Response) GetAttrCode() int {
return r.Code
}
func (r Response) GetAttrResult() []byte {
return r.Result
}
func (r Response) GetAttrHeader() map[string]string {
return r.Headers
}
func (r *Response) SetCode(code int) {
r.Code = code
}
func (r *Response) SetHeaders(key, value string) {
r.Headers[key] = value
}
func exampleResponse() {
var (
response Response
headers map[string]string
)
headers = make(map[string]string)
headers["Server"] = "GitHub.com"
headers["Status"] = "Ok"
response.Headers = headers
response.Code = 200
response.Result = []byte("hello world")
fmt.Println(response.GetAttrCode())
fmt.Println(response.GetAttrHeader())
fmt.Println(response.GetAttrResult())
response.SetCode(404)
fmt.Println(response)
response.SetHeaders("Status", "failed")
fmt.Println(response)
}
func main() {
exampleResponse()
}
>>>
200
map[Server:GitHub.com Status:Ok]
[104 101 108 108 111 32 119 111 114 108 100]
{404 [104 101 108 108 111 32 119 111 114 108 100] map[Server:GitHub.com Status:Ok]}
{404 [104 101 108 108 111 32 119 111 114 108 100] map[Status:failed Server:GitHub.com]}
函数和方法的区别
func NormalFunc(arg int) int {
return arg + 1
}
func (r *Response) SetCode(code int) {
r.Code = code
}
Go 方法是作用在接收者（receiver）上的一个函数。接收者可以是几乎任何类型。
但一般选择 结构体 作为接收者。
组合：
匿名字段
在 Golang 中可以通过结构体的组合实现类的继承。
即：将一个结构体A当成另一个结构体B的匿名字段，则 这个结构体B自动拥有A的所有字段和方法。
type Response struct {
Code int
Result []byte
Headers map[string]string
}
func (r Response) GetAttrCode() int {
return r.Code
}
func (r Response) GetAttrResult() []byte {
return r.Result
}
func (r Response) GetAttrHeader() map[string]string {
return r.Headers
}
func (r *Response) SetCode(code int) {
r.Code = code
}
func (r *Response) SetHeaders(key, value string) {
r.Headers[key] = value
}
type Requests struct {
Url string
Params string
}
type CollectionRequests struct {
CollectionNumber int
Requests
Response
}
func exampleCollectionRequests() {
var collectionRequests CollectionRequests
collectionRequests.CollectionNumber = 10
collectionRequests.Url = "https://www.example.com"
collectionRequests.Params = "name"
collectionRequests.Code = 201
collectionRequests.Result = []byte("hello Golang")
var headers map[string]string
headers = make(map[string]string)
headers["status"] = "Good"
collectionRequests.Headers = headers
fmt.Println(collectionRequests)
fmt.Println(collectionRequests.GetAttrCode())
}
func main() {
exampleCollectionRequests()
}
>>>
{10 {https://www.example.com name} {201 [104 101 108 108 111 32 71 111 108 97 110 103] map[status:Good]}}
201
上文CollectionRequests 拥有两个匿名字段Requests、Response ，则自动拥有这个两个结构体的字段和方法。
内嵌结构体
这个组合的形式会遇到两个问题：
- 字段相同怎么办？即结构体A 有字段 a, 结构体 B 也有字段 a。怎么处理？
- 方法相同怎么办？即结构体A 有方法 methodOne, 结构体 B 也有方法 methodOne。怎么处理？
应该尽量避免命名冲突。同时可以使用多个点号的方法访问字段。方法则优先使用结构体B 的。
type OtherRequests struct {
Request Requests
Resp Response
Code int
}
func (o OtherRequests) GetAttrCode() {
fmt.Println(fmt.Sprintf("Outer Code = %d", o.Code))
fmt.Println(fmt.Sprintf("inner Code = %d", o.Resp.Code))
}
func exampleOtherRequests() {
var other OtherRequests
other.Code = 201
other.Resp.Code = 202
fmt.Println(other)
other.GetAttrCode()
fmt.Println(other.Resp.GetAttrCode())
}
func main() {
exampleOtherRequests()
}
>>>
{{ } {202 [] map[]} 201}
Outer Code = 201
inner Code = 202
202
格式化显示结构体
type OtherRequests struct {
Request Requests
Resp Response
Code int
}
func (o OtherRequests) String() string {
return fmt.Sprintf("Request = %v , Response = %v , Code = %d", o.Request, o.Resp, o.Code)
}
func exampleOtherRequests() {
var other OtherRequests
other.Code = 201
other.Resp.Code = 202
fmt.Println(other)
other.GetAttrCode()
fmt.Println(other.Resp.GetAttrCode())
}
func main() {
exampleOtherRequests()
}
>>>
Request = { } , Response = {202 [] map[]} , Code = 201
Outer Code = 201
inner Code = 202
202
完整示例
package main
import "fmt"
type Response struct {
Code int
Result []byte
Headers map[string]string
}
type Requests struct {
Url string
Params string
}
type OtherRequests struct {
Request Requests
Resp Response
Code int
}
func (o OtherRequests) GetAttrCode() {
fmt.Println(fmt.Sprintf("Outer Code = %d", o.Code))
fmt.Println(fmt.Sprintf("inner Code = %d", o.Resp.Code))
}
func (r Response) GetAttrCode() int {
return r.Code
}
func (r Response) GetAttrResult() []byte {
return r.Result
}
func (r Response) GetAttrHeader() map[string]string {
return r.Headers
}
func (r *Response) SetCode(code int) {
r.Code = code
}
func (r *Response) SetHeaders(key, value string) {
r.Headers[key] = value
}
func (o OtherRequests) String() string {
return fmt.Sprintf("Request = %v , Response = %v , Code = %d", o.Request, o.Resp, o.Code)
}
func exampleOtherRequests() {
var other OtherRequests
other.Code = 201
other.Resp.Code = 202
headers := make(map[string]string)
headers["status"] = "Good"
other.Resp.Headers = headers
other.Resp.Result = []byte("hello Golang")
other.Request.Url = "https://www.example.com"
other.Request.Params = "name"
fmt.Println(other)
other.GetAttrCode()
fmt.Println(other.Resp.GetAttrCode())
}
func main() {
exampleOtherRequests()
}
输出：
Request = {https://www.example.com name} , Response = {202 [104 101 108 108 111 32 71 111 108 97 110 103] map[status:Good]} , Code = 201
Outer Code = 201
inner Code = 202
202