前言

最近在学go，某天意外的看到了极客兔兔的七天用Go从零实现系列，给自己定个小目标。坚持跟极客兔兔学习go，并做个记录。

http.HandleFunc

内置的net/http包提供了http.HandleFunc方法，可以根据不同的访问路径，执行不同的代码片段

func main() {
      
    http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request){
        w.WriteHeader(200) 
        w.Write([]byte("index"))
    })
    http.HandleFunc("/test", func(w http.ResponseWriter, r *http.Request){         //只要请求path等于/test，都会走这个。无关请求方式是POST、GET等

        w.WriteHeader(200) //设置响应头为200
        w.Write([]byte("test")) //设置响应体
    })

    http.ListenAndServe(":9999", nil)
}

http.ListenAndServe

http.ListenAndServe(":9999", nil)，是用来启动一个web服务，其中":9999"，是指监听9999端口。第二个参数，需要传入一个实现了Handler接口的实例，即实现ServeHTTP(ResponseWriter, *Request)这个方法。传nil就会走默认的实例处理（顺带说一句go里的接口实现跟ts里的差不多，更类似于一种约定，并不需要像其他面向对象语言一样使用implements关键字来实现）net/http包底层会调用这个ServeHTTP方法，所以ServeHTTP差不多是我们处理http请求的入口和关键

  type engine struct {
  }

  func (t *engine) ServeHTTP(w http.ResponseWriter, r *http.Request) {
    switch r.URL.Path {
    case "/test" :
        w.WriteHeader(201)
        w.Write([]byte("test1"))
    case "/" :
        w.WriteHeader(201)
        w.Write([]byte("index1"))
    default:
        w.WriteHeader(http.StatusNotFound)
        w.Write([]byte("404 not found"))
    }
}

func main() {
    http.ListenAndServe(":9999", new(engine))
}
  

简单静态路由

利用map将访问路径和处理handle的对应关系缓存起来实现一个简单的路由表

type HandlerFunc func( http.ResponseWriter, *http.Request)
type engine struct {
    router map[string]HandlerFunc
}

func (t *engine) addRoute(method string, pattern string, handler HandlerFunc) {
    key := method + "-" + pattern
    t.router[key] = handler
}
func (t *engine) GET(pattern string, handler HandlerFunc) {
    t.addRoute("GET", pattern, handler)
}

func (t *engine) POST(pattern string, handler HandlerFunc) {
    t.addRoute("POST", pattern, handler)
}

func (t *engine) ServeHTTP(w http.ResponseWriter, r *http.Request) {
    key := r.Method + "-" + r.URL.Path
    if handle, ok := t.router[key]; ok {
        handle(w, r)

    } else {
        w.WriteHeader(http.StatusNotFound)
        w.Write([]byte("not found"))
    }
}

func main() {
    engine := new(engine)
    engine.router = make(map[string]HandlerFunc)

    engine.GET("/test", func(w http.ResponseWriter, r *http.Request) {
        w.WriteHeader(200)
        w.Write([]byte("test"))
    })

    engine.POST("/test", func(w http.ResponseWriter, r *http.Request) {
        w.WriteHeader(http.StatusCreated)
        log.Println(r.Header)
        s,_ := ioutil.ReadAll(r.Body)

        w.Write(s)
    })

    http.ListenAndServe(":9999", engine)
}