Go語(yǔ)言－panic和recover使用實(shí)戰(zhàn)

panic

正常的函數(shù)執(zhí)行流程將立即終止，但函數(shù)中之前使用defer關(guān)鍵字延遲執(zhí)行的語(yǔ)句將正常展開(kāi)執(zhí)行，之后該函數(shù)將返回到調(diào)用函數(shù)，并導(dǎo)致逐層向上執(zhí)行panic()流程，直到所屬的goroutine中所有正在執(zhí)行的函數(shù)將被終止。錯(cuò)誤信息將被報(bào)告，包括panic()的參數(shù)類型interface()我們可以看到，panic可以接收任意類型的數(shù)據(jù)
panic(404)
panic("network borken")
panic("Error("file not exists")

recover

recover函數(shù)用于終止錯(cuò)誤處理流程。recover應(yīng)該在defer關(guān)鍵字的函數(shù)中執(zhí)行以有效截取錯(cuò)誤處理流程

實(shí)例1

package main

import (
    "fmt"
)

func main() {
    defer func() {
        if r := recover(); r != nil {
            fmt.Println("detail:", r)
        }
    }()

    fmt.Println("before painc")
    panic("error1")
    panic("error2")
    fmt.Println("after panic")
    return
}

運(yùn)行結(jié)果

before painc
detail: error1

實(shí)例2

package main

import (
    "fmt"
)

func main() {
    fmt.Println("before painc")
    panic("error1")
    panic("error2")
    fmt.Println("after panic")
    return
}

運(yùn)行結(jié)果

before painc
panic: error1

goroutine 1 [running]:
main.main()
    /home/kenmy/go/src/github.com/shadowsocks/shadowsocks-go/sample-config/panic.go:17 +0xdd

實(shí)例3

package main

import (
    "fmt"
)

func main() {
    defer func() {
        if r := recover(); r != nil {
            fmt.Println("detail:", r)
        }
    }()

    test()
    fmt.Println("end")
    return
}

func test() {
    defer func() {
        if r := recover(); r != nil {
            fmt.Println("detail0:", r)
        }
    }()
    fmt.Println("before painc")
    panic("error1")
    panic("error2")
    fmt.Println("after panic")
}

運(yùn)行結(jié)果

before painc
detail0: error1
end

實(shí)例4

package main

import (
    "fmt"
)

func main() {
    defer func() {
        if r := recover(); r != nil {
            fmt.Println("detail:", r)
        }
    }()

    test()
    fmt.Println("middle")
    panic("error3")
    fmt.Println("end")
    return
}

func test() {
    defer func() {
        if r := recover(); r != nil {
            fmt.Println("detail0:", r)
        }
    }()
    fmt.Println("before painc")
    panic("error1")
    panic("error2")
    fmt.Println("after panic")
}

運(yùn)行結(jié)果

before painc
detail0: error1
middle
detail: error3

實(shí)例5

package main

import (
    "fmt"
)

func main() {

    test()
    fmt.Println("middle")
    panic("error3")
    fmt.Println("end")
    return
}

func test() {
    fmt.Println("before painc")
    panic("error1")
    panic("error2")
    fmt.Println("after panic")
}

運(yùn)行結(jié)果：

before painc
panic: error1

goroutine 1 [running]:
main.test()
    /home/kenmy/go/src/github.com/shadowsocks/shadowsocks-go/sample-config/panic.go:20 +0xdd
main.main()
    /home/kenmy/go/src/github.com/shadowsocks/shadowsocks-go/sample-config/panic.go:10 +0x26