Go1.16新特性embed打包静态资源文件实现

└── cmd 测试目录
    ├── assets 静态资源目录
    │   ├── .idea.txt
    │   ├── golang.txt
    │   └── hello.txt
    └── main.go  测试go源文件

package main
import (
	"embed"
	_ "embed"
	"fmt"
)
//go:embed指令用来嵌入，必须紧跟着嵌入后的变量名
//只支持嵌入为string, byte slice和embed.FS三种类型，这三种类型的别名(alias)和命名类型(如type S string)都不可以
//以字符串形式嵌入 assets/hello.txt
//go:embed assets/hello.txt
var s string
//文件的内容嵌入为slice of byte，也就是一个字节数组
//go:embed assets/hello.txt
var b []byte
//嵌入为一个文件系统 新的文件系统FS
//go:embed assets/hello.txt
//go:embed assets/golang.txt
var f embed.FS
func main() {
	fmt.Println("embed string.", s)
	fmt.Println("embed byte.", string(b))
	data, _ := f.ReadFile("assets/hello.txt")
	fmt.Println("embed fs.", string(data))
	data, _ = f.ReadFile("assets/golang.txt")
	fmt.Println("embed fs.", string(data))
}

//go:embed assets/hello.txt
//go:embed assets/golang.txt
var f embed.FS

//go:embed assets
var f embed.FS
func main() {
	data, _ := f.ReadFile("assets/hello.txt")
	fmt.Println(string(data))
}

├── assets
│   ├── .idea.txt
│   ├── golang.txt
│   └── hello.txt
└── main.go
package main
import (
	"embed"
	_ "embed"
	"fmt"
)
//go:embed assets/*
var f embed.FS
func main() {
	data, _ := f.ReadFile("assets/.idea.txt")
	fmt.Println(string(data))
}

package main
import (
	"embed"
	_ "embed"
	"fmt"
)
//go:embed assets
var f embed.FS
func main() {
	helloFile, _ := f.Open("assets/hello.txt")
	stat, _ := helloFile.Stat()
	fmt.Println(stat.Name(), stat.Size())
}

package main
import (
	"embed"
	_ "embed"
	"fmt"
)
//go:embed assets
var f embed.FS
func main() {
	dirEntries, _ := f.ReadDir("assets")
	for _, de := range dirEntries {
		fmt.Println(de.Name(), de.IsDir())
	}
}

package main
import (
	"embed"
	_ "embed"
	"fmt"
	"io/fs"
	"io/ioutil"
)
//go:embed assets
var f embed.FS
func main() {
	as, _ := fs.Sub(f, "assets")
	hi, _ := as.Open("hello.txt")
	data, _ := ioutil.ReadAll(hi)
	fmt.Println(string(data))
}