我要评论1. defer ： 延迟调用。多个defer，依次入栈，在函数即将退出时，依次出栈调用
1 package main
2 import "fmt"
3 func main() {
4 defer func() {
5 fmt.println("defer one")
6 }()
7 defer func() {
8 fmt.println("defer two")
9 }()
10 defer func() {
11 fmt.println("defer three")
12 }()
13 }
2. panic和defer结合使用：panic触发错误，defer依次出栈调用，没有recover捕获的情况下，最后才打印错误
1 package main
2 import "fmt"
3 func main() {
4 defer func() {
5 fmt.println("defer one")
6 }()
7 defer func() {
8 fmt.println("defer two")
9 }()
10 defer func() {
11 fmt.println("defer three")
12 }()
13 panic("panic here")
14 }
3. defer,panic, recover 结合使用，panic触发错误，defer依次出栈调用，直到被recover捕获，打印捕获的信息，之后继续defer出栈
例一:
1 package main
2 import "fmt"
3 func main() {
4 defer func() {
5 fmt.println("defer one")
6 }()
7 defer func() {
8 fmt.println("defer two")
9 }()
10 defer func() {
11 if info := recover(); info != nil {
12 fmt.println("catch: ", info)
13 }
14 fmt.println("defer three")
15 }()
16 panic("panic here")
17 }
例二：
package main
import "fmt"
func main() {
defer func() {
fmt.println("defer one")
}()
defer func() {
if info := recover(); info != nil {
fmt.println("catch: ", info)
}
fmt.println("defer two")
}()
defer func() {
fmt.println("defer three")
}()
panic("panic here")
}
例三：
package main
import "fmt"
func main() {
defer func() {
if info := recover(); info != nil {
fmt.println("catch: ", info)
}
fmt.println("defer one")
}()
defer func() {
fmt.println("defer two")
}()
defer func() {
fmt.println("defer three")
}()
panic("panic here")
}
4. recover 必须在defer中调用，才有效，否则返回nil
package main
import "fmt"
func main() {
if info := recover(); info != nil {
fmt.println("catch: ", info)
} else {
fmt.println("recover return nil")
}
defer func() {
fmt.println("defer one")
}()
defer func() {
fmt.println("defer two")
}()
defer func() {
fmt.println("defer three")
}()
panic("panic here")
}
5. panic 其后的代码不会执行
例一：
package main
import "fmt"
func main() {
defer func() {
fmt.println("defer one")
}()
defer func() {
fmt.println("defer two")
}()
defer func() {
fmt.println("defer three")
}()
panic("panic here")
if info := recover(); info != nil {
fmt.println("catch: ", info)
} else {
fmt.println("recover return nil")
}
}
例二：
package main
import "fmt"
func main() {
defer func() {
fmt.println("defer one")
}()
defer func() {
if v := recover(); v != nil {
fmt.println("catch panic error: ", v)
}
fmt.println("defer two")
}()
defer func() {
fmt.println("defer three")
}()
panic("panic here")
fmt.println("after panic")
}
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