func main() {//切换工作目录，便于读取对应的请求资源，一定要存在os.Chdir("/Users/yekai/Downloads/webpath")listener, err := net.Listen("tcp", ":8888")if err != nil {log.Panic("Failed to Listen ", err)}defer listener.Close()for {//得到新连接conn, err := listener.Accept()if err != nil {fmt.Println("Failed to Accept ", err)continue}//启动goroutinego handle_conn(conn)}
}

func handle_conn(conn net.Conn) {defer conn.Close()reader := bufio.NewReader(conn)//定义正则表达式解析methdreg := regexp.MustCompile("([a-zA-Z]+) (/.*) (.+)rn")for {//循环读取行msg, err := reader.ReadString('n')if err != nil {fmt.Println("Failed to ReadString", err)break}requests := methdreg.FindAllStringSubmatch(msg, -1)if len(requests) > 0 {fmt.Println(requests[0], len(requests[0]))//顺利得到行后再用goroutine处理go handle_method(conn, requests[0][1], requests[0][2])}}}

func handle_method(conn net.Conn, method string, url string) error {fmt.Println("method=", method, " url=", url)if method == "GET" || method == "get" {//处理get方法 //为什么要加 . 呢？考虑请求资源的信息是什么样的path := "." + url//读取资源信息，间接判断出是否存在info, err := os.Stat(path)if err != nil {fmt.Println("Failed to Stat", err)errinfo, _ := os.Stat("error.html")//发送HTTP协议头部信息sendContext(conn, "error.html", "404", "NOT FOUND", errinfo.Size())//发送文件sendfile(conn, "error.html")return err}if info.IsDir() {//处理目录fd, err := os.Open(path)if err != nil {fmt.Println("Failed to Open ", path, err)return err}infos, err := fd.Readdir(-1)if err != nil {fmt.Println("Failed to Readdir ", err)return err}sendbuf := ""for _, v := range infos {//组织数据列表if v.IsDir() {sendbuf += fmt.Sprintf("<li><a href='%s/'>%s</a></li>", v.Name(), v.Name())} else {sendbuf += fmt.Sprintf("<li><a href='%s'>%s</a></li>", v.Name(), v.Name())}}sendbuf = fmt.Sprintf(index_html, sendbuf)length := len([]byte(sendbuf))sendContext(conn, path, "200", "Ok", int64(length))io.WriteString(conn, sendbuf)} else {//发送HTTP协议头部信息sendContext(conn, path, "200", "Ok", info.Size())//发送文件sendfile(conn, path)}}return nil
}

    //按文件类型分类
func getFileType(filename string) string {filetype := "text/html;charset=utf-8"if strings.HasSuffix(filename, ".jpg") {filetype = "image/jpeg"} else if strings.HasSuffix(filename, ".gif") {filetype = "image/gif"}return filetype
}func sendContext(conn net.Conn, filename, code, codemsg string, length int64) error {io.WriteString(conn, "HTTP/1.1 "+code+" "+codemsg+" rn")sendbuf := fmt.Sprintf("Content-Type: %srn", getFileType(filename))io.WriteString(conn, sendbuf)sendbuf = fmt.Sprintf("Content-Len: %drn", length)io.WriteString(conn, sendbuf)io.WriteString(conn, "rn")return nil
}func sendfile(conn net.Conn, filename string) error {fd, err := os.Open(filename)if err != nil {fmt.Println("Failed to Open ", err, filename)return err}defer fd.Close()//流拷贝n, err := io.Copy(conn, fd)fmt.Println("send file ok, size = ", n)return err
}

localhost:study yekai$ go run webserver.go

http.ListenAndServe(":8899", http.FileServer(http.Dir("/Users/yekai/Downloads/webpath")))