访问：https://golang.org/dl/

下载 go1.12.4.linux-amd64.tar.gz

wget https://dl.google.com/go/go1.12.4.linux-amd64.tar.gz

sudo tar -zxvf go1.12.4.linux-amd64.tar.gz -C /opt

检查安装是否成功

cd /opt/go/bin

./go version

go version go1.12.4 linux/amd64

设置环境变量

vi /etc/profile

export GOROOT=/opt/go
export GOPATH=/home/ubuntu/go
export GOPROXY=https://goproxy.io
export GOARCH=amd64
export GOOS=linux
export GOTOOLS=$GOROOT/pkg/tool
export PATH=$PATH:$GOROOT/bin:$GOPATH/bin

source /etc/profile

其中，GOPROXY 可以解决 golang.org/x/... 系列包无法下载的问题。

编写 HelloWorld 文件，测试运行环境。

package main
import "fmt"
func main(){
    fmt.Println("hello,world!")
}

go run hello.go
go build hello.go 

创建 go.mod 文件

go mod init hello

用 Gin 实现一个简单的 http 服务

import (
    "gopkg.in/gin-gonic/gin.v1"
    "net/http"
)

func main(){
    
    router := gin.Default()

    router.GET("/", func(c *gin.Context) {
        c.String(http.StatusOK, "Hello World")
    })
    router.Run(":8000")
}

直接编译执行 

go run hello

可以看到引用的包都被自动下载了

go: finding github.com/gin-contrib/sse latest
go: finding github.com/gin-gonic/gin/render latest
go: finding github.com/gin-gonic/gin/binding latest
go: finding github.com/gin-gonic/gin/json latest
go: finding golang.org/x/sys v0.0.0-20190222072716-a9d3bda3a223
go: downloading golang.org/x/sys v0.0.0-20190222072716-a9d3bda3a223
go: finding gopkg.in/go-playground/validator.v8 v8.18.2
go: finding github.com/ugorji/go/codec latest
go: finding github.com/golang/protobuf/proto latest
go: finding gopkg.in/yaml.v2 v2.2.2
go: downloading gopkg.in/go-playground/validator.v8 v8.18.2
go: downloading gopkg.in/yaml.v2 v2.2.2
go: finding github.com/ugorji/go v1.1.4
go: finding github.com/golang/protobuf v1.3.1
go: downloading github.com/ugorji/go v1.1.4
go: downloading github.com/golang/protobuf v1.3.1
go: extracting gopkg.in/go-playground/validator.v8 v8.18.2
go: extracting gopkg.in/yaml.v2 v2.2.2
go: extracting github.com/golang/protobuf v1.3.1
go: extracting github.com/ugorji/go v1.1.4
go: extracting golang.org/x/sys v0.0.0-20190222072716-a9d3bda3a223
go: finding gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405

HTTP 服务启动正常，可以通过浏览器访问了。

[GIN-debug] [WARNING] Now Gin requires Go 1.6 or later and Go 1.7 will be required soon.

[GIN-debug] [WARNING] Creating an Engine instance with the Logger and Recovery middleware already attached.

[GIN-debug] [WARNING] Running in "debug" mode. Switch to "release" mode in production.
 - using env:   export GIN_MODE=release
 - using code:  gin.SetMode(gin.ReleaseMode)

[GIN-debug] GET    /                         --> main.main.func1 (3 handlers)
[GIN-debug] Listening and serving HTTP on :8000