重写了ping示例，现在它是一个实用的工具了

cmd/mcping/README.md

@@ -0,0 +1,5 @@
+# mcping
+适用于Minecraft: Java Edition的ping工具
+
+Useage:
+    `mcping <hostname>[:port]`

cmd/mcping/mcping.go

@@ -0,0 +1,89 @@
+// Useage: go run cmd/ping/ping.go localhost
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+
+	"github.com/Tnze/go-mc/bot"
+	"github.com/Tnze/go-mc/chat"
+	uuid "github.com/satori/go.uuid"
+)
+
+type status struct {
+	Description chat.Message
+	Players     struct {
+		Max    int
+		Online int
+		Sample []struct {
+			ID   uuid.UUID
+			Name string
+		}
+	}
+	Version struct {
+		Name     string
+		Protocol int
+	}
+	//favicon ignored
+}
+
+func main() {
+	addr, port := getAddr()
+
+	fmt.Printf("MCPING (%s:%d):\n", addr, port)
+
+	resp, delay, err := bot.PingAndList(addr, port)
+	if err != nil {
+		fmt.Printf("ping and list server fail: %v", err)
+		os.Exit(1)
+	}
+
+	var s status
+	err = json.Unmarshal(resp, &s)
+	if err != nil {
+		fmt.Print("unmarshal resp fail:", err)
+		os.Exit(1)
+	}
+
+	fmt.Print(s)
+	fmt.Println("Delay:", delay)
+}
+
+func getAddr() (string, int) {
+	const useage = "Useage: mcping <hostname>[:port]"
+	if len(os.Args) < 2 {
+		fmt.Println("no host name.", useage)
+		os.Exit(1)
+	}
+
+	addr := strings.Split(os.Args[1], ":")
+	var port int
+	switch len(addr) {
+	case 1:
+		port = 25565
+	case 2:
+		var err error
+		port, err = strconv.Atoi(addr[1])
+		if err != nil {
+			fmt.Println(err, useage)
+			os.Exit(1)
+		}
+	}
+
+	return addr[0], port
+}
+
+func (s status) String() string {
+	var sb strings.Builder
+	fmt.Fprintln(&sb, "Server:", s.Version.Name)
+	fmt.Fprintln(&sb, "Protocol:", s.Version.Protocol)
+	fmt.Fprintln(&sb, "Description:", s.Description)
+	fmt.Fprintf(&sb, "Players: %d/%d\n", s.Players.Online, s.Players.Max)
+	for _, v := range s.Players.Sample {
+		fmt.Fprintf(&sb, "- [%s] %v\n", v.Name, v.ID)
+	}
+	return sb.String()
+}