问golang在子目录中找不到包gin

EN

controllers/user.go:4:2: cannot find package "(underscore)/home/ubuntu/goapi/src/github.com/roes/api/vendor/github.com/gin-gonic/gin" 
in any of: /usr/local/go/src/(underscore)/home/ubuntu/goapi/src/github.com/roes/api/vendor/github.com/gin-gonic/gin (from $GOROOT) 
     /home/ubuntu/goapi/src/_(underscore)/home/ubuntu/goapi/src/github.com/roes/api/vendor/github.com/gin-gonic/gin (from $GOPATH)

GOPATH="/home/ubuntu/goapi"
GOROOT="/usr/local/go"

github.com/rose
 api
  main.go // the loading gin is ok here
  controller
   |-user.go //with import ( "github.com/gin-gonic/gin" ) : error

  package controller

  import (
    "github.com/gin-gonic/gin"
    "net/http"
    //      "github.com/astaxie/beego/orm"
    "../database"
    "../models"
  )

  func init() {
    database.ConnectToDb()
    ORM = database.GetOrmObject()
  }

   //UserController ...
   type UserController struct{}

   func createUser(c *gin.Context) {

export GOPATH=$HOME/go
export PATH=$PATH:$GOPATH/bin

 import( "github.com/gin-gonic/gin")

  package controller
  import( "github.com/gin-gonic/gin")
  func somestring(){
    return "hello world"
  }

   curl https://raw.githubusercontent.com/gin-gonic/gin/master/examples/basic/main.go > main.go

    "./controller"
    "fmt"

        user := new(controller.somestring)
        fmt.Printf(user)

 controller/user.go:4:2: cannot find package "github.com/gin-gonic/gin" in any of:
/usr/local/go/src/github.com/gin-gonic/gin (from $GOROOT)
/home/ubuntu/go/src/github.com/gin-gonic/gin (from $GOPATH)

 08:56:35 ~/go/src/github.com/jerry/core$ cd /home/ubuntu/go/src/github.com/jerry/core/vendor/github.com/gin-gonic/
 08:56:45 ~/go/src/github.com/jerry/core/vendor/github.com/gin-gonic$