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跨域案例go gf ，请求代理，前端请求后端A转后端B

案例：从前端请求后端A（路径携带argusx），后端A转发请求到多个不同地区（可一个）后端B(切掉argusx，其他不变进行请求)，由请求头x-proxy指定请求哪个服务端

方案一：handler形式处理：

func InitRouter() {s := g.Server()// 分组路由注册方式app.Api = s.Group("/argusx", func(group *ghttp.RouterGroup) {// 跨域中间件service.Middleware.InitGroup(group)ReverseProxy(group, "/xxx/")})
}// InitGroup 注册中间件
func (s *middlewareService) InitGroup(group *ghttp.RouterGroup) {group.Middleware(// 跨域处理s.CORS,//s.Auth,)
}
// 使用默认跨域处理
func (s *middlewareService) CORS(r *ghttp.Request) {//r.Response.CORSDefault() //若是请求头没有新的，则直接用default，否则用下面三行代码options := r.Response.DefaultCORSOptions()options.AllowHeaders = options.AllowHeaders + ",X-Proxy"r.Response.CORS(options)r.Middleware.Next()
}
func ReverseProxy(pg *ghttp.RouterGroup, path string) {op := func(r *ghttp.Request) {// 根据code拿到地址，可用自己的方式获取参数argusvoiceCode := r.GetHeader("x-proxy")g.Log().Infof("[argusvoice] argusvoiceCode=%s", argusvoiceCode)if argusvoiceCode != "" {argusvoiceApi := service.GetArgusVoiceUrlByCode(argusvoiceCode)g.Log().Infof("[argusvoice] argusvoiceApi=%s", argusvoiceApi)remote, err := url.Parse(argusvoiceApi)if err != nil {fmt.Println(err.Error())g.Log().Errorf("[argusvoice] url parse error, argusvoiceApi=%s, error=%v", argusvoiceApi, err)}reverseProxy := proxy.GoReverseProxy(&proxy.RProxy{Remote: remote,})if err != nil {fmt.Println(err.Error())r.ExitAll()return}reverseProxy.ServeHTTP(r.Response.Writer, r.Request)r.ExitAll()} else {r.Middleware.Next()}}pg.Bind([]ghttp.GroupItem{{"ALL", path + "*", op}})
}

方案二：中间件的形式代理：
对所有请求都拦截，包括options，这样需要自己处理options请求，options请求是为了协商请求头，所以需要返回成功以及必要信息方便后期请求携带。
请求允许的加上x-proxy，注意option请求是拿不到具体的值
坏处：无法使用框架自带的options处理

s.BindMiddlewareDefault(func(r *ghttp.Request) {// 根据code拿到地址accessControlHeaders := r.Header.Get("Access-Control-Request-Headers")isProxy := strings.Contains(accessControlHeaders, "x-proxy")argusvoiceCode := r.GetHeader("x-proxy")r.Header.Set("Access-Control-Allow-Origin", "*")g.Log().Infof("[argusvoice] argusvoiceCode=%s", argusvoiceCode)if isProxy || (argusvoiceCode != "") {argusvoiceApi := service.GetArgusVoiceUrlByCode(argusvoiceCode)if r.Request.Method == "OPTIONS" {r.Response.Status = 200// 以下头部请参照自己正常请求的头部r.Response.Header().Set("Access-Control-Allow-Origin", r.Header.Get("Origin")) //此处不能写作*r.Response.Header().Set("Access-Control-Allow-Credentials", "true")r.Response.Header().Set("Access-Control-Allow-Headers", "Content-Type,AccessToken,X-CSRF-Token, Authorization, Token, x-token, x-requested-with,Accept,Origin,Referer,User-Agent,x-proxy")r.Response.Header().Set("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, PATCH, DELETE")r.Response.Header().Set("Access-Control-Expose-Headers", "Content-Length, Access-Control-Allow-Origin, Access-Control-Allow-Headers, Content-Type")return}g.Log().Infof("[argusvoice] argusvoiceApi=%s", argusvoiceApi)remote, err := url.Parse(argusvoiceApi)if err != nil {fmt.Println(err.Error())g.Log().Errorf("[argusvoice] url parse error, argusvoiceApi=%s, error=%v", argusvoiceApi, err)}reverseProxy := proxy.GoReverseProxy(&proxy.RProxy{Remote: remote,})if err != nil {fmt.Println(err.Error())r.ExitAll()return}reverseProxy.ServeHTTP(r.Response.Writer, r.Request)r.ExitAll()} else {r.Middleware.Next()}
})

proxy文件：（此处代码大部分抄自https://github.com/hezhizheng/go-reverse-proxy/blob/master/handle.go）
该项目使用案例：https://hzz.cool/blog/implementation-of-simple-http-and-https-reverse-proxy-by-golang

package proxyimport ("github.com/gogf/gf/frame/g""net/http""net/http/httputil""net/url""strings"
)type RProxy struct {Remote *url.URL
}func GoReverseProxy(this *RProxy) *httputil.ReverseProxy {remote := this.Remoteproxy := httputil.NewSingleHostReverseProxy(remote)proxy.Director = func(request *http.Request) {Path := ""targetQuery := remote.RawQueryrequest.URL.Scheme = remote.Schemerequest.URL.Host = remote.Hostrequest.Host = remote.HostPath, request.URL.RawPath = joinURLPath(remote, request.URL)Paths := strings.Split(Path, "/argusx")request.URL.Path = Paths[1]g.Log().Infof("[argusvoice] request.Body=%v", request.Body)if targetQuery == "" || request.URL.RawQuery == "" {request.URL.RawQuery = targetQuery + request.URL.RawQuery} else {request.URL.RawQuery = targetQuery + "&" + request.URL.RawQuery}g.Log().Infof("[argusvoice] request.URL.Path=%s, request.URL.RawQuery=%s", request.URL.Path, request.URL.RawQuery)}proxy.ModifyResponse = func(response *http.Response) error {response.Header.Del("Access-Control-Allow-Origin")response.Header.Del("Access-Control-Allow-Credentials")response.Header.Del("Access-Control-Allow-Headers")response.Header.Del("Access-Control-Allow-Methods")return nil}return proxy
}// go sdk 源码
func joinURLPath(a, b *url.URL) (path, rawpath string) {if a.RawPath == "" && b.RawPath == "" {return singleJoiningSlash(a.Path, b.Path), ""}// Same as singleJoiningSlash, but uses EscapedPath to determine// whether a slash should be addedapath := a.EscapedPath()bpath := b.EscapedPath()aslash := strings.HasSuffix(apath, "/")bslash := strings.HasPrefix(bpath, "/")switch {case aslash && bslash:return a.Path + b.Path[1:], apath + bpath[1:]case !aslash && !bslash:return a.Path + "/" + b.Path, apath + "/" + bpath}return a.Path + b.Path, apath + bpath
}// go sdk 源码
func singleJoiningSlash(a, b string) string {aslash := strings.HasSuffix(a, "/")bslash := strings.HasPrefix(b, "/")switch {case aslash && bslash:return a + b[1:]case !aslash && !bslash:return a + "/" + b}return a + b
}