Golang-为什么我不能在GOPATH/src/project中导入本地软件包，而不能在主目录中导入本地软件包?

我有一个项目，其文件夹结构如下:

I have a project, its folder structure is like following:

    /project
        models/
            Product.go
        main.go

main.go的内容是:

The content of main.go is:

package main

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

func main() {
    r := gin.Default()
    fmt.Println(models.Product{})
    r.GET("/", func(c *gin.Context) {
        c.String(200, "he")
    })

    r.Run(":3000")
}

Product.go的内容为:

The content of Product.go is:

package models

type Product struct {
    Name string
}

我从键入go env得到的是:

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/Mac/go"
GORACE=""
GOROOT="/usr/local/Cellar/go/1.5.3/libexec"
GOTOOLDIR="/usr/local/Cellar/go/1.5.3/libexec/pkg/tool/darwin_amd64"
GO15VENDOREXPERIMENT=""
CC="clang"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -    fmessage-length=0 -fno-common"
CXX="clang++"
CGO_ENABLED="1"

当项目目录的位置为$GOPATH/src/project时，如果运行go run main.go，我得到的是以下错误消息:./main.go:: can't find import: "github.com/gin-gonic/gin".

When the location of the project directory is $GOPATH/src/project, If I run go run main.go, what I get is this error message: ./main.go:: can't find import: "github.com/gin-gonic/gin".

但是当项目目录的位置为~/project时，go run main.go可以正常工作.

But when the location of project directory is ~/project, go run main.go can work as expected.

我使用go1.5.3.

I use go1.5.3.

任何人都可以帮助我.谢谢.

Can anyone help me. Thanks.