匿名结构体有什么用途 特殊场景下的简化代码技巧

Person

package main

import (
    "fmt"
    "testing"
)

func Greet(person struct {
    Name string
    Age  int
}) string {
    return fmt.Sprintf("Hello, %s! You are %d years old.", person.Name, person.Age)
}

func TestGreet(t *testing.T) {
    result := Greet(struct {
        Name string
        Age  int
    }{Name: "Alice", Age: 30})

    expected := "Hello, Alice! You are 30 years old."
    if result != expected {
        t.Errorf("Expected %q, but got %q", expected, result)
    }
}

func main() {
    person := struct {
        Name string
        Age  int
    }{
        Name: "Bob",
        Age:  25,
    }
    greeting := Greet(person)
    fmt.Println(greeting)
}

package main

import (
    "encoding/json"
    "fmt"
    "log"
    "os"
)

func main() {
    // 假设这是你的配置文件内容
    jsonData := []byte(`
    {
        "ServerAddress": "127.0.0.1",
        "ServerPort": 8080,
        "Timeout": 30
    }
    `)

    // 定义一个匿名结构体来映射配置
    var config struct {
        ServerAddress string `json:"ServerAddress"`
        ServerPort    int    `json:"ServerPort"`
        Timeout       int    `json:"Timeout"`
    }

    // 解析JSON数据到匿名结构体
    err := json.Unmarshal(jsonData, &config)
    if err != nil {
        log.Fatalf("Failed to unmarshal JSON: %v", err)
    }

    // 打印解析后的配置
    fmt.Printf("Server Address: %s\n", config.ServerAddress)
    fmt.Printf("Server Port: %d\n", config.ServerPort)
    fmt.Printf("Timeout: %d\n", config.Timeout)

    // 模拟从文件中读取配置
    file, err := os.Open("config.json")
    if err != nil {
        log.Fatalf("Failed to open config file: %v", err)
    }
    defer file.Close()

    decoder := json.NewDecoder(file)
    err = decoder.Decode(&config)
    if err != nil {
        log.Fatalf("Failed to decode config file: %v", err)
    }

    fmt.Printf("Server Address from file: %s\n", config.ServerAddress)
    fmt.Printf("Server Port from file: %d\n", config.ServerPort)
    fmt.Printf("Timeout from file: %d\n", config.Timeout)
}

package main

import (
    "database/sql"
    "fmt"
    "log"

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

func main() {
    // 数据库连接信息
    db, err := sql.Open("mysql", "user:password@tcp(127.0.0.1:3306)/dbname")
    if err != nil {
        log.Fatal(err)
    }
    defer db.Close()

    // 检查数据库连接
    err = db.Ping()
    if err != nil {
        log.Fatal(err)
    }

    // 查询语句
    query := "SELECT name, email FROM users WHERE id = ?"

    // 执行查询
    var user struct {
        Name  string `db:"name"`
        Email string `db:"email"`
    }

    row := db.QueryRow(query, 1) // 假设查询ID为1的用户
    err = row.Scan(&user.Name, &user.Email)
    if err != nil {
        log.Fatal(err)
    }

    // 输出查询结果
    fmt.Printf("User Name: %s, Email: %s\n", user.Name, user.Email)
}