urfave/cli简介
urfave/cli是一个简单、快速、有趣的包，用于在Go中构建命令行应用程序
urfave/cli安装
目前普遍使用的是V2版本，在go中直接安装即可使用
$ go get github.com/urfave/cli/v2
实例讲解
- 在命令行工具中可以参考linux中命令行帮助理解，命令行格式：command [flags] [argument1] [argument2]，命令，选项，参数直接用空格隔开，flags直接以"-"连起来。
- cli 差不多是基于 flag 来开发的哈，我们需要了解一下flag包的的使用，这里简要说明一下flag接受语法
- -isbool (一个 - 符号，布尔类型该写法等同于 -isbool=true)
- -age=x (一个 - 符号，使用等号)
- -age x (一个 - 符号，使用空格)
- --age=x (两个 - 符号，使用等号)
- --age x (两个 - 符号，使用空格)
1. Args的使用
1、创建一个go项目，在main.go文件中写入如下代码
package main
import (
"fmt"
"log"
"os"
"github.com/urfave/cli/v2" //引入包
)
func main() {
app := &cli.App{ //实例化app对象
Action: func(cCtx *cli.Context) error {
fmt.Printf("Hello %q", cCtx.Args().Get(0))
//cCtx.Args()，可以获取运行命令后的参数列表，是一个切片，cCtx.Args().Get(0)是获取
//第一个位置的参数，第二个第三个以此类推
return nil
},
}
if err := app.Run(os.Args); err != nil {
log.Fatal(err)
}
}
运行命令： go run main.go zhangpl
打印： Hello zhangpl
2、标志位（Flags）
可以使用flags进行传参，案例如下
package main
import (
"fmt"
"log"
"os"
"github.com/urfave/cli/v2"
)
func main() {
var language string
app := &cli.App{
Flags: []cli.Flag{
&cli.StringFlag{
Name: "lang",
Value: "english",
Usage: "language for the greeting",
Destination: &language, //此处的变量只能在函数内被取到值
},
},
Action: func(cCtx *cli.Context) error {
name := "someone"
if cCtx.NArg() > 0 { //统计参数的个数
name = cCtx.Args().Get(0)
}
if language == "spanish" { //判定选项值，如果为spanish则走Hola分支
fmt.Println("Hola", name)
} else {
fmt.Println("Hello", name)
}
return nil
},
}
if err := app.Run(os.Args); err != nil {
log.Fatal(err)
}
}
解读代码：
通过flags设立选项，name表示选项名称，valus表示默认值，usage表示用法，
destination表示将扫描的结果绑定到language上，通过命令行可以观察。
PS E:\hsops\go_study\greet> go run greet.go -h
NAME:
greet.exe - A new cli application
USAGE:
greet.exe [global options] command [command options] [arguments...]
COMMANDS:
help, h Shows a list of commands or help for one command
GLOBAL OPTIONS://表示选项
--lang value language for the greeting (default: "english")
--help, -h show help
PS E:\hsops\go_study\greet> go run .\greet.go --lang=english zhangpl //次数--lang表示选项，zhangpl为参数，注意参数跟选项不能混淆
运行结果：Hello zhangpl
3、Aliases的使用
package main
import (
"fmt"
"log"
"os"
"github.com/urfave/cli/v2"
)
func main() {
var language string
app := &cli.App{
Flags: []cli.Flag{
&cli.StringFlag{
Name: "lang",
Aliases: []string{"l", "m"},
Value: "english",
Usage: "language for the greeting",
Destination: &language,
},
},
Action: func(c *cli.Context) error {
name := "anyone"
if c.NArg() > 0 {
name = c.Args().Get(0)
} else {
fmt.Println("No Args")
}
if language == "chinese" {
fmt.Println("Curry", name)
} else {
fmt.Println("James", name)
}
return nil
},
}
if err := app.Run(os.Args); err != nil {
log.Fatal(err)
}
}
PS E:\hsops\go_study\greet> go run .\greet.go -h
NAME:
greet.exe - A new cli application
USAGE:
greet.exe [global options] command [command options] [arguments...]
COMMANDS:
help, h Shows a list of commands or help for one command
GLOBAL OPTIONS:
--lang value, -l value, -m value language for the greeting (default: "english")
--help, -h show help
从上面可以看出options中多了-l和-m，分别使用两个不同的选项进行定义
PS E:\hsops\go_study\greet> go run .\greet.go --m chinese
No Args
Curry anyone
PS E:\hsops\go_study\greet> go run .\greet.go --lang english
No Args
James anyone
可以发现结果一致
4、如果是使用多个命令，则可以使用Commands，
package main
import (
"fmt"
"log"
"os"
"sort"
"github.com/urfave/cli/v2"
)
func main() {
app := &cli.App{
Commands: []*cli.Command{
{
Name: "sex",
Aliases: []string{"s"},
Usage: "你可以通过我来获取性别",
Action: func(c *cli.Context) error {
fmt.Println("难人")
return nil
},
},
{
Name: "age",
Aliases: []string{"a"},
Usage: "你可以通过我来获取年龄",
Action: func(c *cli.Context) error {
fmt.Println("100岁了")
return nil
},
},
},
}
sort.Sort(cli.CommandsByName(app.Commands)) // 通过命令函数来排序，在help中进行展示
err := app.Run(os.Args)
if err != nil {
log.Fatal(err)
}
}
代码解析：
PS E:\hsops\go_study\greet> go run .\greet.go -h
NAME:
greet.exe - A new cli application
USAGE:
greet.exe [global options] command [command options] [arguments...]
COMMANDS:
age, a 你可以通过我来获取年龄
sex, s 你可以通过我来获取性别
help, h Shows a list of commands or help for one command
GLOBAL OPTIONS:
--help, -h show help
通过执行不同的命令获取不同的结果
PS E:\hsops\go_study\greet> go run .\greet.go age
100岁了
5、Subcommands 子命令
package main
import (
"fmt"
"log"
"os"
"github.com/urfave/cli/v2"
)
func main() {
app := &cli.App{
Commands: []*cli.Command{
{
Name: "add",
Aliases: []string{"a"},
Usage: "add a task to the list",
Action: func(cCtx *cli.Context) error {
fmt.Println("added task: ", cCtx.Args().First())
return nil
},
},
{
Name: "complete",
Aliases: []string{"c"},
Usage: "complete a task on the list",
Action: func(cCtx *cli.Context) error {
fmt.Println("completed task: ", cCtx.Args().First())
return nil
},
},
{
Name: "template",
Aliases: []string{"t"},
Usage: "options for task templates",
Subcommands: []*cli.Command{
{
Name: "add",
Usage: "add a new template",
Action: func(cCtx *cli.Context) error {
fmt.Println("new task template: ", cCtx.Args().First())
return nil
},
},
{
Name: "remove",
Usage: "remove an existing template",
Action: func(cCtx *cli.Context) error {
fmt.Println("removed task template: ", cCtx.Args().First())
return nil
},
},
},
},
},
}
if err := app.Run(os.Args); err != nil {
log.Fatal(err)
}
}
代码解析：
任何命令行首先通过--help或者-h进行查看
PS E:\hsops\go_study\greet> go run .\greet.go -h
NAME:
greet.exe - A new cli application
USAGE:
greet.exe [global options] command [command options] [arguments...]
COMMANDS:
add, a add a task to the list
complete, c complete a task on the list
template, t options for task templates
help, h Shows a list of commands or help for one command
GLOBAL OPTIONS:
--help, -h show help
从COMMANDS中可以看出来共有add，complete，template三个command，且template有add，remove两个子命令，templete跟add可以理解为包含关系，可以通过下述命令进行查看
PS E:\hsops\go_study\greet> go run .\greet.go template -h
NAME:
greet.exe template - options for task templates
USAGE:
greet.exe template command [command options] [arguments...]
COMMANDS:
add add a new template
remove remove an existing template
help, h Shows a list of commands or help for one command
OPTIONS:
--help, -h show help
从COMMANDS中可以看到template两个子命令，add和remove
命令行可以用：
PS E:\hsops\go_study\greet> go run .\greet.go add
added task:
PS E:\hsops\go_study\greet> go run .\greet.go template add
new task template:
6、Subcommands categories使用，子命令类别主要是将子命令进行归类，在使用中可以参考如下代码
package main
import (
"fmt"
"log"
"os"
"github.com/urfave/cli/v2"
)
func main() {
app := &cli.App{
Commands: []*cli.Command{
{
Name: "noop",
Usage: "complete a task on the list",
Action: func(cCtx *cli.Context) error {
fmt.Println("noop task: ", cCtx.Args().First())
return nil
},
},
{
Name: "add",
Category: "template",
Usage: "complete a task on the list",
Action: func(cCtx *cli.Context) error {
fmt.Println("completed add task: ", cCtx.Args().First())
return nil
},
},
{
Name: "remove",
Category: "template",
Usage: "complete a task on the list",
Action: func(cCtx *cli.Context) error {
fmt.Println("completed remove task: ", cCtx.Args().First())
return nil
},
},
},
}
if err := app.Run(os.Args); err != nil {
log.Fatal(err)
}
}
代码解析：
PS E:\hsops\go_study\greet> go run .\greet.go -h
greet.exe - A new cli application
USAGE:
greet.exe [global options] command [command options] [arguments...]
COMMANDS:
noop complete a task on the list
help, h Shows a list of commands or help for one command
template:
add complete a task on the list
remove complete a task on the list
GLOBAL OPTIONS:
--help, -h show help
PS E:\hsops\go_study\greet> go run .\greet.go add
completed add task:
PS E:\hsops\go_study\greet> go run .\greet.go remove
completed remove task:
PS E:\hsops\go_study\greet> go run .\greet.go noop
noop task:
通过go run greet.go可以知道不同的命令在不同的分类中，但是具体使用情况没有区别
