Filter主要作用就是在请求的处理之前或者之后来进行一些额外的操作, 比如记录日志、错误处理等等, go-restful里面针对Container、webService、Route都可以加入filter对象 ， 为了串联起这些filter, go-restful里面使用了ChanFilter来保存当前路由的所有关联filter。
Container这个概念比较迷惑人, 通常写web的时候，我们最少要进行两个操作， 写一个业务处理逻辑的handler， 然后定义一个路由吧这个路由绑定到我们的web框架上, 但很多rest框架，都需要很多自定义的逻辑处理, 这时候大家通畅会做一个抽象的实现, 比如router -> dispatch -> handler, 在路由和实际的处理方法之间加入一个dispatch的阶段, 用于自己逻辑的处理和对应请求的转发, go-restful里面的Container主要是实现了一个dispatch方法用来实现上面的chanFilter和router查找功能 。
在rest里面通常需要定义各种各样的资源, 比如用户、商品等, 不同的资源通常都会有一个endpoint来标识这一类比如User、Product等等, WebService其实就可以理解位一个资源的集合, 比如用户服务, 我们可以吧UserResource这类资源定义成一个web service, 所有用户的服务都在这一个wbe serice里面， 同时大家的rootpath也都是易用的/users。
Route就比较简单了, 一个Route里面会保存它的路径、请求方法、处理函数等基本问题。
func ListenAndServe(addr string, handler Handler) error {
server := &Server{Addr: addr, Handler: handler}
return server.ListenAndServe()
}
能看出函数的入口是：Handler 接口
type Handler interface {
ServeHTTP(ResponseWriter, *Request)
}
httpServer 包含 container .
http.ListenAndServe(":9990", apiServer.Container)
一个 Container 包含多个 WebService
type Container struct {
webServicesLock sync.RWMutex
webServices []*WebService
ServeMux *http.ServeMux
isRegisteredOnRoot bool
containerFilters []FilterFunction
doNotRecover bool // default is true
recoverHandleFunc RecoverHandleFunction
serviceErrorHandleFunc ServiceErrorHandleFunction
router RouteSelector // default is a CurlyRouter (RouterJSR311 is a slower alternative)
contentEncodingEnabled bool // default is false
}
container 实现的了Handler 接口
func (c *Container) ServeHTTP(httpwriter http.ResponseWriter, httpRequest *http.Request) {
c.ServeMux.ServeHTTP(httpwriter, httpRequest)
}
一个 webservice 包含多个Route
type WebService struct {
rootPath string
pathExpr *pathExpression // cached compilation of rootPath as RegExp
routes []Route
produces []string
consumes []string
pathParameters []*Parameter
filters []FilterFunction
documentation string
apiVersion string
typeNameHandleFunc TypeNameHandleFunction
dynamicRoutes bool // protects 'routes' if dynamic routes are enabled
routesLock sync.RWMutex
}
一个 Route 包含HTTP 协议协议相关的HTTP Request 、HTTP Reponse 、方法等处理
type Route struct {
Method string
Produces []string
Consumes []string
Path string // webservice root path + described path
Function RouteFunction
Filters []FilterFunction
If []RouteSelectionConditionFunction
// cached values for dispatching
relativePath string
pathParts []string
pathExpr *pathExpression // cached compilation of relativePath as RegExp
// documentation
Doc string
Notes string
Operation string
ParameterDocs []*Parameter
ResponseErrors map[int]ResponseError
ReadSample, WriteSample interface{} // structs that model an example request or response payload
// Extra information used to store custom information about the route.
Metadata map[string]interface{}
// marks a route as deprecated
Deprecated bool
}
具体的处理函数是：RouteFunction
type RouteFunction func(*Request, *Response)
所以整体处理流程如下
- 启动http 服务，指定端口并监听：需要传入端口和Handler 接口
log.Fatal(http.ListenAndServe(":9990", apiServer.Container))
- 定义一个 container ，container 类实现了Handler 接口
apiServer := &APIServer{
Container: restful.DefaultContainer.Add(u.WebService()),
}
- container 内需要定义一个或者多个 webservice, 内含具体的Route 处理函数 RouteFunction
func (u UserResource) WebService() *restful.WebService {
ws := new(restful.WebService)
ws. Path("/users").
Consumes(restful.MIME_XML, restful.MIME_JSON).
Produces(restful.MIME_JSON, restful.MIME_XML) // you can specify this per route as well
ws.Route(ws.GET("/").To(u.findAllUsers).
// docs Doc("get all users").
Writes([]User{}).
Returns(200, "OK", []User{}))
ws.Route(ws.GET("/{user-id}").To(u.findUser).
// docs
Doc("get a user").
Param(ws.PathParameter("user-id", "identifier of the user").DataType("integer").DefaultValue("1")).
Writes(User{}). // on the response
Returns(200, "OK", User{}).
Returns(404, "Not Found", nil))
return ws }
package main
import (
"fmt"
"log"
"net/http"
"github.com/emicklei/go-restful"
)
type User struct {
Name string
Age string
ID []int
}
type UserResource struct {
// normally one would use DAO (data access object)
users map[string]User
}
// WebService creates a new service that can handle REST requests for User resources.
func (u UserResource) WebService() *restful.WebService {
ws := new(restful.WebService)
ws.
Path("/users").
Consumes(restful.MIME_XML, restful.MIME_JSON).
Produces(restful.MIME_JSON, restful.MIME_XML) // you can specify this per route as well
ws.Route(ws.GET("/").To(u.findAllUsers).
// docs
Doc("get all users").
Writes([]User{}).
Returns(200, "OK", []User{}))
ws.Route(ws.GET("/{user-id}").To(u.findUser).
// docs
Doc("get a user").
Param(ws.PathParameter("user-id", "identifier of the user").DataType("integer").DefaultValue("1")).
Writes(User{}). // on the response
Returns(200, "OK", User{}).
Returns(404, "Not Found", nil))
return ws
}
// GET http://localhost:8080/users
//
func (u UserResource) findAllUsers(request *restful.Request, response *restful.Response) {
list := []User{}
for _, each := range u.users {
list = append(list, each)
}
response.WriteEntity(list)
}
func (u UserResource) findUser(request *restful.Request, response *restful.Response) {
id := request.PathParameter("user-id")
usr := u.users[id]
if len(usr.ID) == 0 {
response.WriteErrorString(http.StatusNotFound, "User could not be found.")
} else {
response.WriteEntity(usr)
}
}
func main() {
type APIServer struct {
Container *restful.Container
}
u := UserResource{map[string]User{}}
u.users["xiewei"] = User{
Name: "xiewei",
Age: "20",
ID: []int{1, 2, 3, 4},
}
apiServer := &APIServer{
Container: restful.DefaultContainer.Add(u.WebService()),
}
log.Printf("start listening on localhost:9990")
log.Fatal(http.ListenAndServe(":9990", apiServer.Container))
}