Golang中HTTP服务的分析与设计详解

type Server struct {
   // 请求监听地址
   Addr string
   // 请求核心处理函数
   Handler Handler 
}

http.ListenAndServe(httpAddr, nil)
// ListenAndServe always returns a non-nil error.
// 创造了一个server对象并调用ListenAndServe
func ListenAndServe(addr string, handler Handler) error {
	server := &Server{Addr: addr, Handler: handler}
	return server.ListenAndServe()
}
func (srv *Server) ListenAndServe() error {
  // 如果关闭了http监听则直接返回ErrServerClosed
	if srv.shuttingDown() {
		return ErrServerClosed
	}
	addr := srv.Addr
	if addr == "" {
		addr = ":http"
	}
  // 开启net包的Listen监听方法，根据传入的类型返回监听的对象
	ln, err := net.Listen("tcp", addr)
	if err != nil {
		return err
	}
	return srv.Serve(ln)
}

func (srv *Server) Serve(l net.Listener) error {
	if fn := testHookServerServe; fn != nil {
		fn(srv, l) // call hook with unwrapped listener
	}
	origListener := l
	l = &onceCloseListener{Listener: l}
	defer l.Close()
	if err := srv.setupHTTP2_Serve(); err != nil {
		return err
	}
	if !srv.trackListener(&l, true) {
		return ErrServerClosed
	}
	defer srv.trackListener(&l, false)
	baseCtx := context.Background()
	if srv.BaseContext != nil {
		baseCtx = srv.BaseContext(origListener)
		if baseCtx == nil {
			panic("BaseContext returned a nil context")
		}
	}
	var tempDelay time.Duration // how long to sleep on accept failure
 // 将整个Server对象设置进ctx中，在多个goroutinue中共享
	ctx := context.WithValue(baseCtx, ServerContextKey, srv)
	for {
		rw, err := l.Accept()   // 阻塞等待连接
		if err != nil {
			select {
			case <-srv.getDoneChan():
				return ErrServerClosed
			default:
			}
			if ne, ok := err.(net.Error); ok && ne.Temporary() {
				if tempDelay == 0 {
					tempDelay = 5 * time.Millisecond
				} else {
					tempDelay *= 2
				}
				if max := 1 * time.Second; tempDelay > max {
					tempDelay = max
				}
				srv.logf("http: Accept error: %v; retrying in %v", err, tempDelay)
				time.Sleep(tempDelay)
				continue
			}
			return err
		}
		connCtx := ctx
		if cc := srv.ConnContext; cc != nil {
			connCtx = cc(connCtx, rw)
			if connCtx == nil {
				panic("ConnContext returned nil")
			}
		}
		tempDelay = 0
		c := srv.newConn(rw)
		c.setState(c.rwc, StateNew, runHooks) // before Serve can return
		go c.serve(connCtx)  //Serve a new connection 建立新的连接
	}
}

// serverHandler 代表请求对应的处理逻辑
type serverHandler struct {
	srv *Server
}
// 具体的处理函数
func (sh serverHandler) ServeHTTP(rw ResponseWriter, req *Request) {
	handler := sh.srv.Handler
  //如果入口设置传入了`Handler`，那么调用的就是传入的，否则就是DefaultServeMux
	if handler == nil {
		handler = DefaultServeMux
	}
	if req.RequestURI == "*" && req.Method == "OPTIONS" {
		handler = globalOptionsHandler{}
	}
	if req.URL != nil && strings.Contains(req.URL.RawQuery, ";") {
		var allowQuerySemicolonsInUse int32
		req = req.WithContext(context.WithValue(req.Context(), silenceSemWarnContextKey, func() {
			atomic.StoreInt32(&allowQuerySemicolonsInUse, 1)
		}))
		defer func() {
			if atomic.LoadInt32(&allowQuerySemicolonsInUse) == 0 {
				sh.srv.logf("http: URL query contains semicolon, which is no longer a supported separator; parts of the query may be stripped when parsed; see golang.org/issue/25192")
			}
		}()
	}
	handler.ServeHTTP(rw, req)
}

package framework
import "net/http"
type Core struct {
}
func (c Core) ServeHTTP(writer http.ResponseWriter, request *http.Request) {
   panic("implement me")
}
func NewCore() *Core {
   return &Core{}
}

package main
import (
   "log"
   "net/http"
   "testdemo1/coredemo/framework"
)
func main() {
   server:=&http.Server{Addr: ":8080",Handler: framework.NewCore()}
   err := server.ListenAndServe()
    if err!=nil{
       log.Fatal(err)
   }
}