go的错误处理机制跟php的完全不一样,go讲究的是:
go的错误分为3种:
1:编译时错误,在编译时抛出的错误,例如有变量未出现使用,变量未声明直接使用等,此错误是在运行之前被编译器找出报错的
2:运行时业务自行抛出的错误(Error),此错误可以直接通过函数返回值返回,由调用栈接收处理,如果不处理则不会影响程序运行
3:通过panic 函数抛出的错误,此错误无法被调用栈拦截,但可以在之后由recover接收并忽略,但是无法恢复原来的调用栈
自行抛出的error错误
例如:
代码语言：javascript复制package main
import (
"errors"
"fmt"
)
func main() {
var a, b float64
a = 10
b = 0
result, err := division(a, b)
if err != nil {
fmt.Printf("出错了:%s", err)
}
fmt.Printf("%f 除于 %f 等于 %f", a, b, result)
}
/**
除法
*/
func division(num1, num2 float64) (float64, error) {
if num2 == 0 {
return 0, errors.New("0不能作为除数")
}
return num1 / num2, nil
}输出:
代码语言：javascript复制出错了:0不能作为除数10.000000 除于 0.000000 等于 0.000000在示例中,如果函数出现业务异常,只能通过errors.New进行return错误数据,
再由调用函数接收error并做判断处理
也可以声明错误结构体,并声明函数方法实现error接口,使其抛出异常:
代码语言：javascript复制package main
import (
"fmt"
)
type DivideError struct {
num1 float64
num2 float64
}
func (receiver DivideError) Error() string {
strFormat := `
Cannot proceed, the divider is zero.
dividee: %d
divider: 0
`
return fmt.Sprintf(strFormat, receiver. num2)
}
func main() {
var a, b float64
a = 10
b = 0
result,err := division(a, b)
if err!=nil {
fmt.Printf("出错了:%s",err)
return
}
fmt.Printf("%f 除于 %f 等于 %f",a,b,result)
}
/**
除法
*/
func division(num1, num2 float64) (float64, error) {
//if num2 == 0 {
// return 0, errors.New("0不能作为被除数")
//}
fmt.Println(num2)
if num2 == 0 {
divisionError := DivideError{num1: num1 ,num2: num2}
return 0, divisionError
}
return num1 / num2,nil
}输出
代码语言：javascript复制GOROOT=/Users/tioncico/sdk/go1.17.6 #gosetup
GOPATH=null #gosetup
/Users/tioncico/sdk/go1.17.6/bin/go build -o /private/var/folders/y7/b5kdfsqx12vchqdhjh4b0mth0000gn/T/___go_build_LearnGoProject_ . #gosetup
/private/var/folders/y7/b5kdfsqx12vchqdhjh4b0mth0000gn/T/___go_build_LearnGoProject_
0
出错了:
Cannot proceed, the divider is zero.
dividee: %!d(float64=0)
divider: 0panic函数抛出错误
如果你访问数组时越界,go将自动检查并调用panic抛出错误:
代码语言：javascript复制package main
import (
"fmt"
)
func main() {
arr := make([]int,3)
fmt.Println(arr[4])
fmt.Println("结束") //此行不会运行
}将输出:
代码语言：javascript复制GOROOT=/Users/tioncico/sdk/go1.17.6 #gosetup
GOPATH=null #gosetup
/Users/tioncico/sdk/go1.17.6/bin/go build -o /private/var/folders/y7/b5kdfsqx12vchqdhjh4b0mth0000gn/T/___go_build_main_go /Users/tioncico/GolandProjects/LearnGoProject/main.go #gosetup
/private/var/folders/y7/b5kdfsqx12vchqdhjh4b0mth0000gn/T/___go_build_main_go
panic: runtime error: index out of range [4] with length 3
goroutine 1 [running]:
main.main()
/Users/tioncico/GolandProjects/LearnGoProject/main.go:10 0x1d
Process finished with exit code 2在panic函数调用后,并不是立即结束进程,而是会调用该协程中的defer函数,例如:
代码语言：javascript复制package main
import (
"fmt"
)
func main() {
defer func() {
fmt.Println("defer 1")
}()
defer func() {
fmt.Println("defer 2")
}()
defer func() {
fmt.Println("defer 3")
}()
arr := make([]int,3)
fmt.Println(arr[4])
fmt.Println("结束") //此行不会被运行
}在结束后,会依次通过栈 先入后出的形式调用defer:
代码语言：javascript复制GOROOT=/Users/tioncico/sdk/go1.17.6 #gosetup
GOPATH=null #gosetup
/Users/tioncico/sdk/go1.17.6/bin/go build -o /private/var/folders/y7/b5kdfsqx12vchqdhjh4b0mth0000gn/T/___go_build_main_go /Users/tioncico/GolandProjects/LearnGoProject/main.go #gosetup
/private/var/folders/y7/b5kdfsqx12vchqdhjh4b0mth0000gn/T/___go_build_main_go
defer 3
defer 2
defer 1
panic: runtime error: index out of range [4] with length 3
goroutine 1 [running]:
main.main()
/Users/tioncico/GolandProjects/LearnGoProject/main.go:18 0x67可通过 recover接收错误
代码语言：javascript复制package main
import (
"fmt"
)
func main() {
defer func() {
err := recover()
fmt.Println("defer 1")
fmt.Println("出现了错误:")
fmt.Println(err)
}()
arr := make([]int,3)
fmt.Println(arr[4])
fmt.Println("结束")
}输出:
代码语言：javascript复制GOROOT=/Users/tioncico/sdk/go1.17.6 #gosetup
GOPATH=null #gosetup
/Users/tioncico/sdk/go1.17.6/bin/go build -o /private/var/folders/y7/b5kdfsqx12vchqdhjh4b0mth0000gn/T/___go_build_main_go /Users/tioncico/GolandProjects/LearnGoProject/main.go #gosetup
/private/var/folders/y7/b5kdfsqx12vchqdhjh4b0mth0000gn/T/___go_build_main_go
defer 1
出现了错误:
runtime error: index out of range [4] with length 3
Process finished with exit code 0通过recover函数可以获取到错误信息,并且可以通过此信息做一些其他操作(例如记录日志等)
但是可以看出,在recover之后,程序并没有继续运行,("结束"依旧没打印)
如果是在其他调用栈调用的情况:
代码语言：javascript复制package main
import (
"fmt"
)
func main() {
test()
fmt.Println("结束")
}
func test() {
defer func() {
err := recover()
fmt.Println("defer 1")
fmt.Println("出现了错误:")
fmt.Println(err)
}()
arr := make([]int,3)
fmt.Println(arr[4])
}将输出:
代码语言：javascript复制GOROOT=/Users/tioncico/sdk/go1.17.6 #gosetup
GOPATH=null #gosetup
/Users/tioncico/sdk/go1.17.6/bin/go build -o /private/var/folders/y7/b5kdfsqx12vchqdhjh4b0mth0000gn/T/___go_build_main_go /Users/tioncico/GolandProjects/LearnGoProject/main.go #gosetup
/private/var/folders/y7/b5kdfsqx12vchqdhjh4b0mth0000gn/T/___go_build_main_go
defer 1
出现了错误:
runtime error: index out of range [4] with length 3
结束可以看到,在其他调用栈调用panic recover之后,只会影响运行panic的调用栈,而不是影响上层调用
在服务器场景中,可能需要同时处理多个请求,每个请求的操作互不影响,可以通过此操作,使得请求错误之后,不会影响其他请求栈
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