学习go的HTTP代码。先创建一个简单的web服务。
package main
import (
"fmt"
"log"
"net/http"
)
func response(w http.ResponseWriter, r *http.Request) {
fmt.Fprintf(w, "Hello world!") //这个写入到w的是输出到客户端的
}
func main() {
http.HandleFunc("/", response)
err := http.ListenAndServe(":9000", nil)
if err != nil {
log.Fatal("ListenAndServe: ", err)
}
}
http.HandleFunc("/", response)func HandleFunc(pattern string, handler func(ResponseWriter, *Request)) {
DefaultServeMux.HandleFunc(pattern, handler)
}
var DefaultServeMux = &defaultServeMux
var defaultServeMux ServeMux
type ServeMux struct {
mu sync.RWMutex//读写锁。并发处理需要的锁
m map[string]muxEntry//路由规则map。一个规则一个muxEntry
hosts bool //规则中是否带有host信息
}
一个路由规则字符串，对应一个handler处理方法。
type muxEntry struct {
h Handler
pattern string
}
DefaultServeMuxServeMuxmuxEntryhttp.HandleFuncDefaultServeMux.HandleFuncmux.HandleHandlerFunc(handler)func (mux *ServeMux) HandleFunc(pattern string, handler func(ResponseWriter, *Request)) {
mux.Handle(pattern, HandlerFunc(handler))
}
type Handler interface {
ServeHTTP(ResponseWriter, *Request) // 路由实现器
}
type HandlerFunc func(ResponseWriter, *Request)
func (f HandlerFunc) ServeHTTP(w ResponseWriter, r *Request) {
f(w, r)
}
HandlerFuncresponseServeHTTPmux.Handlefunc (mux *ServeMux) Handle(pattern string, handler Handler) {
mux.mu.Lock()
defer mux.mu.Unlock()
if pattern == "" {
panic("http: invalid pattern")
}
if handler == nil {
panic("http: nil handler")
}
if _, exist := mux.m[pattern]; exist {
panic("http: multiple registrations for " pattern)
}
if mux.m == nil {
mux.m = make(map[string]muxEntry)
}
mux.m[pattern] = muxEntry{h: handler, pattern: pattern}
if pattern[0] != '/' {
mux.hosts = true
}
}
handlerServeMux.mmapmapmuxEntryhandlerhttp.ListenAndServe(":9000", nil)func ListenAndServe(addr string, handler Handler) error {
server := &Server{Addr: addr, Handler: handler}
return server.ListenAndServe()
}
func (srv *Server) ListenAndServe() error {
addr := srv.Addr
if addr == "" {
addr = ":http"
}
ln, err := net.Listen("tcp", addr)
if err != nil {
return err
}
return srv.Serve(tcpKeepAliveListener{ln.(*net.TCPListener)})
}
net.Listen("tcp", addr)addrtcpKeepAliveListeneraddrfunc (srv *Server) Serve(l net.Listener) error {
defer l.Close()
if fn := testHookServerServe; fn != nil {
fn(srv, l)
}
var tempDelay time.Duration // how long to sleep on accept failure
if err := srv.setupHTTP2_Serve(); err != nil {
return err
}
srv.trackListener(l, true)
defer srv.trackListener(l, false)
baseCtx := context.Background() // base is always background, per Issue 16220
ctx := context.WithValue(baseCtx, ServerContextKey, srv)
for {
rw, e := l.Accept()
if e != nil {
select {
case <-srv.getDoneChan():
return ErrServerClosed
default:
}
if ne, ok := e.(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", e, tempDelay)
time.Sleep(tempDelay)
continue
}
return e
}
tempDelay = 0
c := srv.newConn(rw)
c.setState(c.rwc, StateNew) // before Serve can return
go c.serve(ctx)
}
}
forl.Accept()c := srv.newConn(rw)ConnConn(srv,rw)c.servec.serverdec.readRequest(ctx)serverHandler{c.server}.ServeHTTP(w, w.req)func (sh serverHandler) ServeHTTP(rw ResponseWriter, req *Request) {
handler := sh.srv.Handler
if handler == nil {
handler = DefaultServeMux
}
if req.RequestURI == "*" && req.Method == "OPTIONS" {
handler = globalOptionsHandler{}
}
handler.ServeHTTP(rw, req)
}
handlerListenAndServeDefaultServeMuxDefaultServeMuxDefaultServeMuxServeHTTPreponseServeHTTP我们看下流程图