七天实现web框架--分组路由

在项目中我们很多时候会对一组的路由进行处理，我们应该如何实现这个功能呢。目前来说，我们进行的都是单个路由的处理。

分组的实现

今天的内容不是很多，我们对router文件进行改在。
在分组的时候，给每个组要用自己的中间件，也就是共有的中间件，所以我们首先实现一个结构体

type RouterGroup struct {
    prefix      string
    middlewares []HandlerFunc // support middleware
    parent      *RouterGroup  // support nesting
    engine      *Engine       // all groups share a Engine instance
}

然后engine要实现所以的功能，所以我们要进行一个改造：

func New() *Engine {
    engine := &Engine{router: newRouter()}
    engine.RouterGroup = &RouterGroup{engine: engine}
    engine.groups = []*RouterGroup{engine.RouterGroup}
    return engine
}

然后下面是我们是我们总体的代码：

package gee

import (
    "log"
    "net/http"
)

type RouterGroup struct {
    prefix      string
    middlewares []HandlerFunc // support middleware
    parent      *RouterGroup  // support nesting
    engine      *Engine       // all groups share a Engine instance
}

// HandlerFunc defines the request handler used by gee
type HandlerFunc func(*Context)

// Engine implement the interface of ServeHTTP
type Engine struct {
    *RouterGroup
    router *router
    groups []*RouterGroup // store all groups
}

// New is the constructor of gee.Engine
func New() *Engine {
    engine := &Engine{router: newRouter()}
    engine.RouterGroup = &RouterGroup{engine: engine}
    engine.groups = []*RouterGroup{engine.RouterGroup}
    return engine
}

// Group is defined to create a new RouterGroup
// remember all groups share the same Engine instance
func (group *RouterGroup) Group(prefix string) *RouterGroup {
    engine := group.engine
    newGroup := &RouterGroup{
        prefix: group.prefix + prefix,
        parent: group,
        engine: engine,
    }
    engine.groups = append(engine.groups, newGroup)
    return newGroup
}

func (group *RouterGroup) addRoute(method string, comp string, handler HandlerFunc) {
    pattern := group.prefix + comp
    log.Printf("Route %4s - %s", method, pattern)
    group.engine.router.addRoute(method, pattern, handler)
}

// GET defines the method to add GET request
func (group *RouterGroup) GET(pattern string, handler HandlerFunc) {
    group.addRoute("GET", pattern, handler)
}

// POST defines the method to add POST request
func (group *RouterGroup) POST(pattern string, handler HandlerFunc) {
    group.addRoute("POST", pattern, handler)
}

// Run defines the method to start a http server
func (engine *Engine) Run(addr string) (err error) {
    return http.ListenAndServe(addr, engine)
}

//这里就是最后的处理函数，这里开始建立的上下文。
func (engine *Engine) ServeHTTP(w http.ResponseWriter, req *http.Request) {
    c := newContext(w, req)
    engine.router.handle(c)
}