windows – goapp serve：无法找到dev_appserver.py

if p := os.Getenv("APPENGINE_DEV_APPSERVER"); p != "" {
  return p,nil
}
return "",fmt.Errorf("unable to find dev_appserver.py")

因此,仔细检查是否在使用goapp时,实际设置了APPENGINE_DEV_APPSERVER环境变量.
例如,参见这个设置该变量的gotool.bat脚本
(但dsymonds正确points out你不应该直接设置它,你应该总是使用goapp)：

@echo off
:: Copyright 2012 Google Inc. All rights reserved.
:: Use of this source code is governed by the Apache 2.0
:: license that can be found in the LICENSE file.
setlocal
set GOROOT=%~dp0goroot
set APPENGINE_DEV_APPSERVER=%~dp0dev_appserver.py
set GOARCH=
set GOBIN=
set GOOS=

:: Set a GOPATH if one is not set.
if not "%GOPATH%"=="" goto havepath
set GOPATH=%~dp0gopath
:havepath

%GOROOT%bin%~n0.exe %*