Mygin实现上下文

本篇是Mygin的第三篇

目的

• 将路由独立出来，方便后续扩展修改
• 上下文Context，对http.ResponseWriter和http.Request进行封装，实现对JSON、HTML等的支持

路由

新建一个router文件，将 Mygin实现简单的路由 中将路由部分复制出来

• 新建Mygin/router.go

package mygin

import (
	"log"
	"net/http"
)

// 路由节点
type methodTree struct {
	method string
	paths  map[string]func(c *Context)
}

type methodTrees map[string]methodTree

type Router struct {
	trees methodTrees
}

// 获取路由root根
func (r *Router) getRoot(method string) methodTree {
	if root, ok := r.trees[method]; ok {
		return root
	}
	r.trees[method] = methodTree{method: method, paths: make(map[string]func(c *Context))}
	return r.trees[method]
}

// 添加路由方法
func (r *Router) addRoute(method, path string, ctx func(c *Context)) {
	root := r.getRoot(method)

	if _, ok := root.paths[path]; ok {
		log.Default().Println(path, "is exist")
		return
	}

	root.method = method
	root.paths[path] = ctx

}

// Get Get方法
func (r *Router) Get(path string, handler func(c *Context)) {
	r.addRoute(http.MethodGet, path, handler)
}

// Post  Post方法
func (e *Engine) Post(path string, handler func(c *Context)) {
	e.addRoute(http.MethodPost, path, handler)
}

• 修改Mygin/engine.go文件

package mygin

import (
	"net/http"
)

type Engine struct {
	Router
}

func (e *Engine) ServeHTTP(w http.ResponseWriter, r *http.Request) {

	if tree, ok := e.trees[r.Method]; ok {
		if handler, ok := tree.paths[r.URL.Path]; ok {
			handler(w, r)
			return
		}
	}
	w.Write([]byte("404 Not found!\n"))
}

// Default returns an Engine
func Default() *Engine {
	return &Engine{
		Router{
			trees: make(methodTrees, 2),
		}}
}

// Run 启动方法start a http server
func (e *Engine) Run(addr string) {
	err := http.ListenAndServe(addr, e)
	if err != nil {
		return
	}
}

• 相当于engine继承router，engine可以调用router中的方法。

上下文

对于1个请求来说，无法就是接收http.Request的数据处理，然后将处理后的数据http.ResponseWriter返回。虽然响应的消息体(Body)不一样，但对于同一种类型比如JSON类型，消息头(Header)和消息体(Body)，而 Header 包含了状态码(StatusCode)，消息类型(ContentType)等几乎每次请求都需要重新写，所以进行封装，对于后续扩展和修改都非常必要。

• 新建mygin/context.go文件

package mygin

import (
	"encoding/json"
	"net/http"
)

type Context struct {
	Request *http.Request
	Writer  http.ResponseWriter
}

func writeContentType(w http.ResponseWriter, value []string) {
	header := w.Header()
	if val := header["Content-Type"]; len(val) == 0 {
		header["Content-Type"] = value
	}

}

func (c *Context) Status(code int) {
	c.Writer.WriteHeader(code)
}

func (c *Context) JSON(v interface{}) error {
	writeContentType(c.Writer, []string{"application/json; charset=utf-8"})
	encoder := json.NewEncoder(c.Writer)
	err := encoder.Encode(v)
	if err != nil {
		c.Status(http.StatusInternalServerError)
	}
	c.Status(http.StatusOK)
	return err
}

func (c *Context) Html(v string) error {
	writeContentType(c.Writer, []string{"text/html; charset=utf-8"})
	c.Status(http.StatusOK)
	_, err := c.Writer.Write([]byte(v))
	return err
}

func (c *Context) String(v string) error {
	writeContentType(c.Writer, []string{"text/plain; charset=utf-8"})
	c.Status(http.StatusOK)
	_, err := c.Writer.Write([]byte(v))
	return err
}

• 在context中实现了JSON、Html、String方法

main.go文件修改

package main

import (
	"gophp/mygin"
)

func main() {
	engine := mygin.Default()
	engine.Get("/json", func(c *mygin.Context) {
		c.JSON(map[string]interface{}{
			"name":     "zs",
			"password": "1234",
		})
	})

	engine.Get("/html", func(c *mygin.Context) {
		c.Html("<h1>hello html!</h1>")
	})

	engine.Get("/string", func(c *mygin.Context) {
		c.String("string...")
	})

	engine.Run(":9501")
}

接下来看实际效果

curl -i http://localhost:9501/json
HTTP/1.1 200 OK
Content-Type: application/json; charset=utf-8
Date: Wed, 17 Jan 2024 05:52:28 GMT
Content-Length: 32

{"name":"zs","password":"1234"}

 ~ curl -i http://localhost:9501/html
HTTP/1.1 200 OK
Content-Type: text/html; charset=utf-8
Date: Wed, 17 Jan 2024 05:52:36 GMT
Content-Length: 20

<h1>hello html!</h1>                                                                                                  

~ curl -i http://localhost:9501/string
HTTP/1.1 200 OK
Content-Type: text/plain; charset=utf-8
Date: Wed, 17 Jan 2024 05:52:42 GMT
Content-Length: 9

string...