golang的defer,recover,panic用法

示例如下:

package main

import (
    "fmt"
)

func defer_call() {
    defer func() {
        fmt.Println("before")
    }()

    defer func() {
        if p := recover(); p != nil {
            fmt.Println("normal panic")
        } else {
            fmt.Println("no panic")
        }
    }()

    defer func() {
        fmt.Println("after")
    }()

    panic("panic")

    fmt.Println("come on")
}

func main() {
    defer_call()
}

輸出:

after
normal panic
before

defer按照先進後出的原則執行.
recover()截獲了panic()的行爲, recover()返回的值不爲nil. 否則爲空.
由於觸發了panic, 字符串”come on”沒有被輸出.