golang并发编程使用Select语句的实现

select {
case val1 := <-ch1:
    // 当从 ch1 接收到数据时执行
case ch2 <- val2:
    // 当向 ch2 发送数据时执行
case <-time.After(time.Second):
    // 如果一秒内没有任何通道操作成功，则执行此 case
default:
    // 如果没有任何通道操作成功，立即执行此 case
}

package main

import (
    "fmt"
    "time"
)

func main() {
    ch1 := make(chan int)
    ch2 := make(chan int)

    go func() {
        time.Sleep(time.Second)
        ch1 <- 1
    }()

    go func() {
        time.Sleep(2 * time.Second)
        ch2 <- 2
    }()

    for i := 0; i < 2; i++ {
        select {
        case msg1 := <-ch1:
            fmt.Println("Received", msg1)
        case msg2 := <-ch2:
            fmt.Println("Received", msg2)
        }
    }
}

package main

import (
    "fmt"
    "time"
)

func main() {
    ch := make(chan int)

    go func() {
        time.Sleep(2 * time.Second)
        ch <- 42
    }()

    select {
    case msg := <-ch:
        fmt.Println("Received:", msg)
    case <-time.After(1 * time.Second):
        fmt.Println("Timeout")
    }
}

package main

import "fmt"

func main() {
    ch := make(chan int)

    select {
    case msg := <-ch:
        fmt.Println("Received:", msg)
    default:
        fmt.Println("No data received")
    }
}