1. 向已关闭的chan写
会直接panic，报 send to close channel错误
package main
func main() {
// 创建缓冲区为4的字符串chan
schoolChan := make(chan string, 4)
// 放入3个值
schoolChan <- "国防科大"
schoolChan <- "北京大学"
schoolChan <- "湖南大学"
// 关闭chan
close(schoolChan)
// 尝试写数据，会panic: send to close channel
schoolChan <- "中南大学"
}
2. 向已关闭的chan读
会返回2个值，若已关闭的chan中还存在值，第二个值为true，第一个值为对应的chan中的值，若已关闭的chan中不存在值，第二个值为false，第一个值为对应chan类型的零值
package main
import "fmt"
func main() {
// 创建缓冲区为4的字符串chan
schoolChan := make(chan string, 4)
// 放入3个值
schoolChan <- "国防科大"
schoolChan <- "北京大学"
schoolChan <- "湖南大学"
// 关闭chan
close(schoolChan)
// 向已关闭的chan读
if school, isEmpty := <-schoolChan; isEmpty {
fmt.Println("school:", school)
}
// 向已关闭的chan读
if school, isEmpty := <-schoolChan; isEmpty {
fmt.Println("school:", school)
}
// 向已关闭的chan读
if school, isEmpty := <-schoolChan; isEmpty {
fmt.Println("school:", school)
}
// 向若chan不存在元素，则第二个参数的值为 false
if school, isEmpty := <-schoolChan; isEmpty {
fmt.Println("school:", school)
}
}
使用for循环遍历chan，若chan未关闭则会堵塞等待chan放入元素，如chan关闭则取出chan内所有元素并终止循序
package main
import (
"fmt"
)
func main() {
// 创建缓冲区为4的字符串chan
schoolChan := make(chan string, 4)
// 放入3个值
schoolChan <- "国防科大"
schoolChan <- "北京大学"
schoolChan <- "湖南大学"
// 关闭chan
close(schoolChan)
// for循环遍历channel，会将已关闭的chan中缓冲区的数据取出完后终止循序
for school := range schoolChan {
fmt.Println("school:", school)
}
}
