improve ghttp.Request for making the request body reusable for multiple times

.example/net/ghttp/server/body.go

@@ -0,0 +1,22 @@
+package main
+
+import (
+	"fmt"
+	"github.com/gogf/gf/frame/g"
+	"github.com/gogf/gf/net/ghttp"
+	"io/ioutil"
+)
+
+func main() {
+	s := g.Server()
+	s.SetIndexFolder(true)
+	s.BindHandler("/", func(r *ghttp.Request) {
+		body1 := r.GetBody()
+		body2, _ := ioutil.ReadAll(r.Body)
+		fmt.Println(body1)
+		fmt.Println(body2)
+		r.Response.Write("hello world")
+	})
+	s.SetPort(8999)
+	s.Run()
+}