对于golang初学者来说，go语言不像java有maven管理那么方便。依赖包的管理无从下手，往往遇到包冲突后解决问题束手无策。从网上随意找一些第三方的工具包使用，使用过程感觉就是一团乱，用起来各种不方便。官方为了golang语言更好的发展，推出官方依赖管理工具dep。dep是一个原型依赖管理工具，需要在Go 1.7及更高的版本中使用。而且dep在新版本中发展也相对比较成熟，使用简单。

安装

go get -u github.com/golang/dep/cmd/dep

使用

$GOPATH/src/项目

首先初始化：

dep init

项目目录下出现了两个文件（Gopkg.lock、Gopkg.toml）和一个目录（vendor）。

接下来看下Gopkg.lock、Gopkg.toml文件内容：

$ cat Gopkg.lock

# This file is autogenerated, do not edit; changes may be undone by the next 'dep ensure'.

[solve-meta]

analyzer-name = "dep"

analyzer-version = 1

inputs-digest = "ab4fef131ee828e96ba67d31a7d690bd5f2f42040c6766b1b12fe856f87e0ff7"

solver-name = "gps-cdcl"

solver-version = 1

$ cat Gopkg.toml

# Gopkg.toml example

#

# Refer to

# for detailed Gopkg.toml documentation.

#

# required = ["github.com/user/thing/cmd/thing"]

# ignored = ["github.com/user/project/pkgX", "bitbucket.org/user/project/pkgA/pkgY"]

#

# [[constraint]]

# name = "github.com/user/project"

# version = "1.0.0"

#

# [[constraint]]

# name = "github.com/user/project2"

# branch = "dev"

# source = "github.com/myfork/project2"

#

# [[override]]

# name = "github.com/x/y"

# version = "2.4.0"

通过一个例子来看具体使用：在项目的main文件下

package main

import (

"github.com/astaxie/beego"

"github.com/bitly/go-simplejson"

"runtime"

)

func main() {

maxCPU := runtime.NumCPU()

runtime.GOMAXPROCS(maxCPU)

strJson := `{"announcer": {"nickname": "时间简史", "kind": "user", "created_at": 1494904539000, "updated_at": 1494983507000, "track_id": 38088960}}`

mapJson,_:=simplejson.NewJson([]byte(strJson))

println(mapJson)

beego.Run()

}

上面已经dep init初始化后，

执行：dep ensure包依赖下载集中管理：

补充：如果遇到版本依赖可执行类似语句:dep ensure -add github.com/bitly/go-simplejson@=0.4.3

再来看下Gopkg.lock、Gopkg.toml文件变化：

$ vim Gopkg.toml

[[constraint]]

name = "github.com/astaxie/beego"

version = "1.8.3"

[[constraint]]

name = "github.com/bitly/go-simplejson"

version = "0.5.0"

$ vim Gopkg.lock

[[projects]]

name = "github.com/astaxie/beego"

packages = [".","config","context","context/param","grace","logs","session","toolbox","utils"]

revision = "cab8458c1c4a5a3b4bf5192922be620e6dede15b"

version = "v1.8.3"

[[projects]]

name = "github.com/bitly/go-simplejson"

packages = ["."]

revision = "aabad6e819789e569bd6aabf444c935aa9ba1e44"

version = "v0.5.0"

[solve-meta]

analyzer-name = "dep"

analyzer-version = 1

inputs-digest = "dc040fb12390d61768be6388ad2935bdd7f9cc93d4b1fdda421a284058277c80"

solver-name = "gps-cdcl"

solver-version = 1

在项目下可以看到vendor目录，已经把依赖包集中管理。后续可以直接做交叉编译，不必担心包管理问题。

小结：

dep的依赖包每一次都是拉取新的还是优先使用本地cache呢？可以肯定的是dep也是有本地缓存的，可以打开$GOPATH/pkg/dep/看看，是不是存在呢！

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