Golang异常处理之defer,panic,recover的使用详解

package main
import "fmt"
func main() {
 defer funA()
 funB()
 funC()
 fmt.Println("main...over....") }
func funA() {
 fmt.Println("我是funA()...") }
func funB() { //
 fmt.Println("我是funB()...") }
func funC() {
 fmt.Println("我是funC()。。") }

package main
import "fmt"
func main() {
 s1 := []int{78, 109, 2, 563, 300}
 largest(s1) }
func finished() {
 fmt.Println("结束！") }
func largest(s []int) {
 defer finished()
 fmt.Println("开始寻找最⼤数...")
 max := s[0]
 for _, v := range s {
 if v > max {
 max = v
 }
 }
 fmt.Printf("%v中的最⼤数为：%v \n", s , max) }

package main
import "fmt"
type person struct {
 firstName string
 lastName string
}
func (p person) fullName() {
 fmt.Printf("%s %s", p.firstName, p.lastName) }
func main() {
 p := person{"Steven", "Wang"}
 defer p.fullName()
 fmt.Printf("Welcome ") }

package main
import "fmt"
func printAdd(a , b int) {
 fmt.Printf("延迟函数中：参数a , b分别为%d,%d ，两数之和为：%d\n",
a , b , a+b) }
func main() {
 a := 5
 b := 6
 //延迟函数的参数在执⾏延迟语句时被执⾏，⽽不是在执⾏实际的函数调
⽤时执⾏。
 defer printAdd(a , b)
 a = 10
 b = 7
 fmt.Printf("延迟函数执⾏前：参数a , b分别为%d,%d ，两数之和为：
%d\n", a , b , a+b) }

package main
import "fmt"
func main() {
 name := "StevenWang欢迎学习区块链"
 fmt.Printf("原始字符串: %s\n", name)
 fmt.Println("翻转后字符串: ")
 ReverseString(name) }
func ReverseString(str string) {
 for _, v := range []rune(str) {
 defer fmt.Printf("%c", v)
 }
}

package main
import (
 "fmt"
 "sync"
)
type rect struct {
 length int
 width int
}
func (r rect) area(wg *sync.WaitGroup) {
 if r.length < 0 {
 fmt.Printf("rect %v's length should be greater than zero\n", r)
 wg.Done()
 return
 }
 if r.width < 0 {
 fmt.Printf("rect %v's width should be greater than zero\n", r)
 wg.Done()
 return
 }
 area := r.length * r.width
 fmt.Printf("rect %v's area %d\n", r, area)
 wg.Done()
}
func main() {
 var wg sync.WaitGroup
 r1 := rect{-67, 89}
 r2 := rect{5, -67}
 r3 := rect{8, 9}
 rects := []rect{r1, r2, r3}
 for _, v := range rects {
 wg.Add(1)
 go v.area(&wg)
 }
 wg.Wait()
 fmt.Println("All go routines finished executing")
}

package main
import (
 "fmt"
 "sync"
)
type rect struct {
 length int
 width int
}
func (r rect) area(wg *sync.WaitGroup) {
 defer wg.Done()
 if r.length < 0 {
 fmt.Printf("rect %v's length should be greater than zero\n", r)
 return
 }
 if r.width < 0 {
 fmt.Printf("rect %v's width should be greater than zero\n", r)
 return
 }
 area := r.length * r.width
 fmt.Printf("rect %v's area %d\n", r, area) }
func main() {
 var wg sync.WaitGroup
 r1 := rect{-67, 89}
 r2 := rect{5, -67}
 r3 := rect{8, 9}
 rects := []rect{r1, r2, r3}
 for _, v := range rects {
 wg.Add(1)
 go v.area(&wg)
 }
 wg.Wait()
 fmt.Println("All go routines finished executing")
}

package main
import "fmt"
func main() {
 /*
 panic：词义"恐慌"，
 recover："恢复"
 go语⾔利⽤panic()，recover()，实现程序中的极特殊的异常的处理
 panic(),让当前的程序进⼊恐慌，中断程序的执⾏
 recover(),让程序恢复，必须在defer函数中执⾏
 */
 funA()
 funB()
 funC()
 fmt.Println("main...over....") }
func funA() {
 fmt.Println("我是函数funA()...") }
func funB() { //外围函数
 defer func() {
 if msg := recover(); msg != nil {
 fmt.Println(msg, "恢复啦。。。")
 }
 }()
 fmt.Println("我是函数funB()...")
 for i := 1; i <= 10; i++ {
 fmt.Println("i:", i)
 if i == 5 {
 //让程序中断
 panic("funB函数，恐慌啦。。。") //打断程序的执⾏。。
 }
 }
 //当外围函数中的代码引发运⾏恐慌时，只有其中所有的延迟函数都执⾏完毕后，该运
⾏时恐慌才会真正被扩展⾄调⽤函数。
}
func funC() {
 defer func() {
 fmt.Println("func的延迟函数。。。")
 //if msg := recover(); msg != nil {
 // fmt.Println(msg, "恢复啦。。。")
 //}
 fmt.Println("recover执⾏了" , recover())
 }()
 fmt.Println("我是函数funC()。。")
 panic("funC恐慌啦。。") }