让Go“恐慌”的十种方法

本内容来源于书籍《Go语言编程之旅》

本文内容将运行让Go程序遇到“恐慌”的代码例子

数组/切片索引越界

package main

import "fmt"

func main() {
	names := []string{
		"1",
		"2",
		"3",
	}
	name := names[len(names)]  //应该改为 names[len(names) - 1]
	fmt.Printf("name: %s",name)  //panic: runtime error: index out of range [3] with length 3
}

空指针调用

package main

type User struct {
	Name string
}

func (u *User)GetName() string {
	return u.Name
}

func main() {
	s := &User{Name: "Neo"}
	s = nil
	s.GetName()  //panic: runtime error: invalid memory address or nil pointer dereference
}

过早关闭HTTP响应体

package main

import (
	"log"
	"net/http"
)

func main() {
	resp,err := http.Get("https://xxx")
	defer resp.Body.Close()  //panic: runtime error: invalid memory address or nil pointer dereference
	if err != nil {
		log.Fatalf("http.Get err: %v",err)
	}
}

除以零

package main

func divide(a,b int) int {
	return a / b
}

func main() {
	divide(1,0)  //panic: runtime error: integer divide by zero
}

向已经关闭的通道发送消息

package main

func main() {
	ch := make(chan string,1)
	ch <- "neo"
	close(ch)
	ch <- "come on"  //panic: send on closed channel
}

重复关闭通道

package main

func main() {
	ch := make(chan string,1)
	ch <- "neo"
	close(ch)
	close(ch)  //panic: close of closed channel
}

关闭未初始化的通道

package main

func main() {
	var ch chan string
	close(ch)  //panic: close of nil channel
}

未初始化map

package main

func main() {
	var m map[string]string
	m["neo"] = "come on"  //panic: assignment to entry in nil map
}

跨协程的“恐慌”处理

package main

import (
	"log"
	"time"
)

func main() {
	go func() {
		defer func() {
			if err := recover();err != nil {
				log.Fatalf("revover err: %v",err)
			}
		}()
		handle()
	}()
	time.Sleep(time.Second)
}

func handle() {
	go divide(1,0)
}

func divide(a,b int) int {
	return a / b  //panic: runtime error: integer divide by zero
}

sync计数为负值

package main

import "sync"

func main() {
	wg := sync.WaitGroup{}
	wg.Add(-1)  //panic: sync: negative WaitGroup counter
	wg.Wait()
}

代码地址