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。裸奔谁都会，但作为一款企业级的基础开发框架，对严谨及安全性的要求大于性能，因此默认情况下，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。
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。
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。
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：
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nginx的error.log）。 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。如果异常包含堆栈信息，默认情况下会打印到Server的error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！
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。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
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