如何在Golang中配置环境变量保证跨平台

package main

import (
    "fmt"
    "os"
)

func main() {
    // 读取环境变量，未设置时返回空字符串
    dbHost := os.Getenv("DB_HOST")
    if dbHost == "" {
        dbHost = "localhost" // 默认值
    }
    fmt.Println("Database Host:", dbHost)
}

go get github.com/joho/godotenv

package main

import (
    "fmt"
    "log"
    "os"

    "github.com/joho/godotenv"
)

func main() {
    // 加载同目录下的 .env 文件
    err := godotenv.Load()
    if err != nil {
        log.Fatal("Error loading .env file")
    }

    dbUser := os.Getenv("DB_USER")
    fmt.Println("DB User:", dbUser)
}

DB_USER=myuser
DB_PASSWORD=mypassword
DB_HOST=localhost

env := os.Getenv("GO_ENV")
if env == "" {
    env = "development"
}
err := godotenv.Load(fmt.Sprintf(".env.%s", env))
if err != nil {
    log.Printf("No %s env file found, trying default .env", env)
    godotenv.Load() // fallback
}

go build -ldflags "-X main.version=1.0.0" main.go

var version = "dev"

func main() {
    fmt.Println("Version:", version) // 输出传入值
}