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Version: 2.3.x

由于这个问题问得比较多,因此专门为大家撰写了这一章节。

基本介绍

目前大多数 Golang 的第三方 WebServer 库均没有默认对 HTTP 请求处理过程中产生的异常进行捕获,轻者错误产生后无法记录到日志造成排查错困难,重则异常造成进程直接崩溃,服务不可用。

当你选择 goframe,你很幸运。作为一款企业级的基础开发框架,默认情况下,执行过程中产生的 panic 是有被 Server 自动捕获的,产生 panic 时当前执行流程会立即中止,但是绝对不会影响进程直接崩溃。

获取异常错误

HTTP 执行流程中产生 panic 异常时,默认处理是记录到 Server 的日志文件中。当然,开发者也可以通过注册中间件方式手动捕获,然后自定义相关的错误处理。这一操作其实在中间件章节的示例中也有介绍,我们这里来再仔细说明下。

相关方法

异常的捕获我们通过 Request 对象中的 GetError 方法获取。

开发者不能通过 recover 方法来捕获异常,因为 goframe 框架的 Server 已经做了捕获,并且为保证默认情况下异常不会引起进程崩溃,因此不会再次往上抛异常。

// GetError returns the error occurs in the procedure of the request.
// It returns nil if there's no error.
func (r *Request) GetError() error

该方法往往使用在流程控制组件中,如后置中间件或者 HOOK 钩子方法中。

使用示例

我们这里使用一个全局的后置中间件来捕获异常,当异常产生后,捕获并写入到指定的日志文件中,返回固定友好的提示信息,避免敏感的报错信息暴露给调用端。

需要注意的是:

  • 即使开发者有自己捕获记录异常错误的日志,但是 Server 依旧会打印到 Server 自己的错误日志文件中。由开发者调用日志接口方法输出的日志属于业务日志(与业务相关),而 Server 自行管理的日志属于服务日志(类似于 nginxerror.log)。
  • 由于 goframe 框架大部分的底层错误都包含有错误时的堆栈信息,如果对于 error 的具体堆栈信息感兴趣(具体调用链、报错文件路径、源码行号等),可以使用 gerror 来获取,具体请参考 错误处理-堆栈特性 章节。如果异常包含堆栈信息,默认情况下会打印到 Servererror 日志文件中。
package main

import (
"github.com/gogf/gf/v2/frame/g"
"github.com/gogf/gf/v2/net/ghttp"
)

func MiddlewareErrorHandler(r *ghttp.Request) {
r.Middleware.Next()
if err := r.GetError(); err != nil {
// 记录到自定义错误日志文件
g.Log("exception").Error(err)
//返回固定的友好信息
r.Response.ClearBuffer()
r.Response.Writeln("服务器居然开小差了,请稍后再试吧!")
}
}

func main() {
s := g.Server()
s.Use(MiddlewareErrorHandler)
s.Group("/api.v2", func(group *ghttp.RouterGroup) {
group.ALL("/user/list", func(r *ghttp.Request) {
panic("db error: sql is xxxxxxx")
})
})
s.SetPort(8199)
s.Run()
}

执行后,我们通过 curl 工具来试试吧:

$ curl -v "http://127.0.0.1:8199/api.v2/user/list"
> GET /api.v2/user/list HTTP/1.1
> Host: 127.0.0.1:8199
> User-Agent: curl/7.61.1
> Accept: */*
>
< HTTP/1.1 500 Internal Server Error
< Server: GF HTTP Server
< Date: Sun, 19 Jul 2020 07:44:30 GMT
< Content-Length: 52
< Content-Type: text/plain; charset=utf-8
<
服务器居然开小差了,请稍后再试吧!

获取异常堆栈

异常堆栈信息

WebServer 本身在捕获异常时,如果抛出的异常信息并不包含堆栈内容,那么 WebServer 会自动获取抛出异常位点(即 panic 的位置)的堆栈并创建一个新的包含该堆栈信息的错误对象。我们来看一个示例。

package main

import (
"github.com/gogf/gf/v2/frame/g"
"github.com/gogf/gf/v2/net/ghttp"
)

func MiddlewareErrorHandler(r *ghttp.Request) {
r.Middleware.Next()
if err := r.GetError(); err != nil {
r.Response.ClearBuffer()
r.Response.Writef("%+v", err)
}
}

func main() {
s := g.Server()
s.Use(MiddlewareErrorHandler)
s.Group("/api.v2", func(group *ghttp.RouterGroup) {
group.ALL("/user/list", func(r *ghttp.Request) {
panic("db error: sql is xxxxxxx")
})
})
s.SetPort(8199)
s.Run()
}

可以看到,我们通过 %+v 的格式化打印来获取异常错误中的堆栈信息,具体原理请参考章节: 错误处理-堆栈特性。执行后,我们通过 curl 工具来测试下:

$ curl "http://127.0.0.1:8199/api.v2/user/list"
db error: sql is xxxxxxx
1. db error: sql is xxxxxxx
1). main.main.func1.1
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/.example/other/test.go:25
2). github.com/gogf/gf/v2/net/ghttp.(*middleware).Next.func1.8
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/net/ghttp/ghttp_request_middleware.go:111
3). github.com/gogf/gf/v2/net/ghttp.niceCallFunc
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/net/ghttp/ghttp_func.go:46
4). github.com/gogf/gf/v2/net/ghttp.(*middleware).Next.func1
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/net/ghttp/ghttp_request_middleware.go:110
5). github.com/gogf/gf/v2/util/gutil.TryCatch
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/util/gutil/gutil.go:46
6). github.com/gogf/gf/v2/net/ghttp.(*middleware).Next
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/net/ghttp/ghttp_request_middleware.go:47
7). main.MiddlewareErrorHandler
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/.example/other/test.go:10
8). github.com/gogf/gf/v2/net/ghttp.(*middleware).Next.func1.9
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/net/ghttp/ghttp_request_middleware.go:117
9). github.com/gogf/gf/v2/net/ghttp.niceCallFunc
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/net/ghttp/ghttp_func.go:46
10). github.com/gogf/gf/v2/net/ghttp.(*middleware).Next.func1
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/net/ghttp/ghttp_request_middleware.go:116
11). github.com/gogf/gf/v2/util/gutil.TryCatch
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/util/gutil/gutil.go:46
12). github.com/gogf/gf/v2/net/ghttp.(*middleware).Next
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/net/ghttp/ghttp_request_middleware.go:47
13). github.com/gogf/gf/v2/net/ghttp.(*Server).ServeHTTP
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/net/ghttp/ghttp_server_handler.go:122

错误堆栈信息

如果抛出的异常是一个通过 gerror 组件的错误对象,或者实现堆栈打印接口的错误对象,由于该异常的错误对象已经包含了详细的堆栈信息,那么 WebServer 将会直接返回该错误对象,不会自动创建错误对象。我们来看一个示例。

package main

import (
"github.com/gogf/gf/v2/errors/gerror"
"github.com/gogf/gf/v2/frame/g"
"github.com/gogf/gf/v2/net/ghttp"
)

func MiddlewareErrorHandler(r *ghttp.Request) {
r.Middleware.Next()
if err := r.GetError(); err != nil {
r.Response.ClearBuffer()
r.Response.Writef("%+v", err)
}
}

func DbOperation() error {
// ...
return gerror.New("DbOperation error: sql is xxxxxxx")
}

func UpdateData() {
err := DbOperation()
if err != nil {
panic(gerror.Wrap(err, "UpdateData error"))
}
}

func main() {
s := g.Server()
s.Use(MiddlewareErrorHandler)
s.Group("/api.v2", func(group *ghttp.RouterGroup) {
group.ALL("/user/list", func(r *ghttp.Request) {
UpdateData()
})
})
s.SetPort(8199)
s.Run()
}

执行后,我们通过 curl 工具来测试下:

$ curl "http://127.0.0.1:8199/api.v2/user/list"
UpdateData error: DbOperation error: sql is xxxxxxx
1. UpdateData error
1). main.UpdateData
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/.example/other/test.go:25
2). main.main.func1.1
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/.example/other/test.go:34
3). github.com/gogf/gf/v2/net/ghttp.(*middleware).Next.func1.8
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/net/ghttp/ghttp_request_middleware.go:111
4). github.com/gogf/gf/v2/net/ghttp.niceCallFunc
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/net/ghttp/ghttp_func.go:46
5). github.com/gogf/gf/v2/net/ghttp.(*middleware).Next.func1
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/net/ghttp/ghttp_request_middleware.go:110
6). github.com/gogf/gf/v2/util/gutil.TryCatch
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/util/gutil/gutil.go:46
7). github.com/gogf/gf/v2/net/ghttp.(*middleware).Next
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/net/ghttp/ghttp_request_middleware.go:47
8). main.MiddlewareErrorHandler
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/.example/other/test.go:10
9). github.com/gogf/gf/v2/net/ghttp.(*middleware).Next.func1.9
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/net/ghttp/ghttp_request_middleware.go:117
10). github.com/gogf/gf/v2/net/ghttp.niceCallFunc
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/net/ghttp/ghttp_func.go:46
11). github.com/gogf/gf/v2/net/ghttp.(*middleware).Next.func1
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/net/ghttp/ghttp_request_middleware.go:116
12). github.com/gogf/gf/v2/util/gutil.TryCatch
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/util/gutil/gutil.go:46
13). github.com/gogf/gf/v2/net/ghttp.(*middleware).Next
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/net/ghttp/ghttp_request_middleware.go:47
14). github.com/gogf/gf/v2/net/ghttp.(*Server).ServeHTTP
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/net/ghttp/ghttp_server_handler.go:122
2. DbOperation error: sql is xxxxxxx
1). main.DbOperation
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/.example/other/test.go:19
2). main.UpdateData
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/.example/other/test.go:23
3). main.main.func1.1
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/.example/other/test.go:34
4). github.com/gogf/gf/v2/net/ghttp.(*middleware).Next.func1.8
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/net/ghttp/ghttp_request_middleware.go:111
5). github.com/gogf/gf/v2/net/ghttp.niceCallFunc
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/net/ghttp/ghttp_func.go:46
6). github.com/gogf/gf/v2/net/ghttp.(*middleware).Next.func1
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/net/ghttp/ghttp_request_middleware.go:110
7). github.com/gogf/gf/v2/util/gutil.TryCatch
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/util/gutil/gutil.go:46
8). github.com/gogf/gf/v2/net/ghttp.(*middleware).Next
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/net/ghttp/ghttp_request_middleware.go:47
9). main.MiddlewareErrorHandler
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/.example/other/test.go:10
10). github.com/gogf/gf/v2/net/ghttp.(*middleware).Next.func1.9
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/net/ghttp/ghttp_request_middleware.go:117
11). github.com/gogf/gf/v2/net/ghttp.niceCallFunc
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/net/ghttp/ghttp_func.go:46
12). github.com/gogf/gf/v2/net/ghttp.(*middleware).Next.func1
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/net/ghttp/ghttp_request_middleware.go:116
13). github.com/gogf/gf/v2/util/gutil.TryCatch
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/util/gutil/gutil.go:46
14). github.com/gogf/gf/v2/net/ghttp.(*middleware).Next
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/net/ghttp/ghttp_request_middleware.go:47
15). github.com/gogf/gf/v2/net/ghttp.(*Server).ServeHTTP
/Users/john/Workspace/Go/GOPATH/src/github.com/gogf/gf/v2/net/ghttp/ghttp_server_handler.go:122