try around interceptor

base.go

package controllers

import (
	"fmt"
	"time"

	"github.com/astaxie/beego"
	"github.com/astaxie/beego/context"
)

type BaseController struct {
	beego.Controller
	start int64
	end   int64
}

func (this BaseController) RenderString(s string) {
	this.Ctx.WriteString(s)
}

func (this *BaseController) Init(ctx *context.Context, childName string, app interface{}) {
	this.Controller.Init(ctx, childName, app)

	this.start = time.Now().UnixNano()
	println("init")
}

func (this *BaseController) Prepare() {
	this.Controller.Prepare()

	println("prepare")
}

func (this *BaseController) Finish() {
	this.Controller.Finish()

	this.end = time.Now().UnixNano()

	println("end")
	cost := (this.end - this.start) / (1000 * 1000.0)
	fmt.Printf("cost time: %d ms.", cost)
	println("")
	// 这时候已经迟了！！！
	this.Ctx.ResponseWriter.Header().Add("x-runtime", fmt.Sprintf("%d", cost))
}

func (this *BaseController) Render() error {
	//this.Controller.Render()
	println("render")
	return nil
}


	beego.Controller
	start int64
	end   int64
}

func (this BaseController) RenderString(s string) {
	this.Ctx.WriteString(s)
}

func (this *BaseController) Init(ctx *context.Context, childName string, app interface{}) {
	this.Controller.Init(ctx, childName, app)

	this.start = time.Now().UnixNano()
	println("init")
}

func (this *BaseController) Prepare() {
	this.Controller.Prepare()

	println("prepare")
}

func (this *BaseController) Finish() {
	this.Controller.Finish()

	this.end = time.Now().UnixNano()

	println("end")
	cost := (this.end - this.start) / (1000 * 1000.0)
	fmt.Printf("cost time: %d ms.", cost)
	println("")
	// 这时候已经迟了！！！
	this.Ctx.ResponseWriter.Header().Add("x-runtime", cost)
}

///////////////////////////////////////////
type MainController struct {
  BaseController
}

func (this *MainController) Get() {
	println("before get")
	time.Sleep(time.Second * 2)

	this.RenderString("hello,world!")
	println("after get")
} 

default.go

package controllers

import (
	"time"
)

type MainController struct {
	BaseController
}

func (this *MainController) Get() {
	println("before get")
	time.Sleep(time.Second * 2)

	this.RenderString("hello,world!")
	println("after get")
}