效果如图：

 main.go文件代码如下：

package mainimport "fmt"
import "net/http"func main()  {fmt.Printf("网站开始运行，地址：http://localhost:8080")http.HandleFunc("/", func(writer http.ResponseWriter, request *http.Request) {_, _ = writer.Write([]byte("Hello world!"))})_ = http.ListenAndServe(":8080", nil)
}