Go http.ListenAndServe 报错

```go package main import ( "io/ioutil" "net/http" "os" ) func main() { http.HandleFunc("/list/", func(writer http.ResponseWriter, request *http.Request) { path := request.URL.Path[len("/list/"):] file, err := os.Open(path) if err != nil { panic(err) } defer file.Close() all, err := ioutil.ReadAll(file) if err != nil { panic(err) } writer.Write(all) }) err := http.ListenAndServe("0.0.0.0:8000 ", nil) if err != nil { panic(err) } } ``` panic: listen tcp: lookup tcp/8000 : nodename nor servname provided, or not known goroutine 1 [running]: main.main() /Users/doufangyu/GolandProjects/Go-Learngo/errhandling/filelistenserver/web.go:29 +0x7f 求大佬给个解决思路