Golang HTTP编程的源码解析详解

func timeHandler(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "%v", time.Now().Format(time.RFC3339))
}
 
func helloHandler(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "%v", "hello world.")
}
 
func main() {
    // 1. 新建路由解码器
    h := http.NewServeMux()
    // 2. 路由注册
    h.HandleFunc("/hello", helloHandler)
    h.HandleFunc("/time", timeHandler)
    // 3. 服务启动 阻塞监听
    http.ListenAndServe(":8000", h)
}

type ServeMux struct {
    mu    sync.RWMutex
    m     map[string]muxEntry
    es    []muxEntry // slice of entries sorted from longest to shortest.
    hosts bool       // whether any patterns contain hostnames
}
type muxEntry struct {
    h       Handler
    pattern string
}
// NewServeMux allocates and returns a new ServeMux.
func NewServeMux() *ServeMux { return new(ServeMux) }

type Handler interface {
    ServeHTTP(ResponseWriter, *Request)
}

// HandleFunc registers the handler function for the given pattern.
func (mux *ServeMux) HandleFunc(pattern string, handler func(ResponseWriter, *Request)) {
    ...
    mux.Handle(pattern, HandlerFunc(handler))
}
 
func (mux *ServeMux) Handle(pattern string, handler Handler) {
    ...
    e := muxEntry{h: handler, pattern: pattern}
    mux.m[pattern] = e
    if pattern[len(pattern)-1] == '/' {
        mux.es = appendSorted(mux.es, e)
    }
    ...
}

func (f HandlerFunc) ServeHTTP(w ResponseWriter, r *Request) {
    f(w, r)
}

func ListenAndServe(addr string, handler Handler) error {
    server := &Server{Addr: addr, Handler: handler}
    return server.ListenAndServe()
}
func (srv *Server) ListenAndServe() error {
    ...
    ln, err := net.Listen("tcp", addr)
    if err != nil {
        return err
    }
    return srv.Serve(ln)
}

func (srv *Server) Serve(l net.Listener) error {
    ...
    for {
        rw, err := l.Accept()
        ...
        c := srv.newConn(rw)
        c.setState(c.rwc, StateNew, runHooks) // before Serve can return
        go c.serve(connCtx)
    }
}
// Serve a new connection.
func (c *conn) serve(ctx context.Context) {
    ...
    serverHandler{c.server}.ServeHTTP(w, w.req)
    ...
}
func (sh serverHandler) ServeHTTP(rw ResponseWriter, req *Request) {
    handler := sh.srv.Handler
    ...
    handler.ServeHTTP(rw, req)
}

// ServeHTTP dispatches the request to the handler whose
// pattern most closely matches the request URL.
func (mux *ServeMux) ServeHTTP(w ResponseWriter, r *Request) {
    ...
    h, _ := mux.Handler(r) // 通过路由获取处理函数
    h.ServeHTTP(w, r)
}