Golang 프로그래머에게 필수: 공통 라이브러리 및 실제 응용 프로그램 요약

package main

import (
    "fmt"
    "net/http"
)

func mainHandler(w http.ResponseWriter, r *http.Request) {
    fmt.Fprint(w, "Hello, World!")
}

func main() {
    http.HandleFunc("/", mainHandler)
    http.ListenAndServe(":8080", nil)
}

package main

import "github.com/gin-gonic/gin"

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

    r.GET("/", func(c *gin.Context) {
        c.String(http.StatusOK, "Hello, World!")
    })

    r.Run(":8080")
}

package main

import (
    "database/sql"
    "fmt"

    _ "github.com/go-sql-driver/mysql"
)

func main() {
    db, err := sql.Open("mysql", "user:password@tcp(host:port)/database")
    if err != nil {
        fmt.Println("Failed to connect to database:", err)
        return
    }
    defer db.Close()

    rows, err := db.Query("SELECT * FROM users")
    if err != nil {
        fmt.Println("Failed to query from database:", err)
        return
    }
    defer rows.Close()

    for rows.Next() {
        var id int
        var name string
        err := rows.Scan(&id, &name)
        if err != nil {
            fmt.Println("Failed to scan rows:", err)
            return
        }
        fmt.Println("ID:", id, "Name:", name)
    }
}

package main

import (
    "fmt"

    "gorm.io/driver/mysql"
    "gorm.io/gorm"
)

type User struct {
    ID   uint
    Name string
}

func main() {
    dsn := "user:password@tcp(host:port)/database"
    db, err := gorm.Open(mysql.Open(dsn), &gorm.Config{})
    if err != nil {
        fmt.Println("Failed to connect to database:", err)
        return
    }
    defer db.Close()

    var users []User
    result := db.Find(&users)
    if result.Error != nil {
        fmt.Println("Failed to query from database:", result.Error)
        return
    }

    for _, user := range users {
        fmt.Println("ID:", user.ID, "Name:", user.Name)
    }
}

package main

import (
    "log"
    "os"
)

func main() {
    file, err := os.Create("app.log")
    if err != nil {
        log.Fatal("Failed to create log file:", err)
    }
    defer file.Close()

    log.SetOutput(file)
    log.Println("This is a log message")
}

package main

import "go.uber.org/zap"

func main() {
    logger, _ := zap.NewProduction()
    defer logger.Sync()

    logger.Info("This is a log message")
}