问如何从表头检索表单数据信息

EN

@Injectable()
export class MyHttpInterceptor implements HttpInterceptor {
    constructor() {}

    intercept(req: HttpRequest < any > , next: HttpHandler): Observable < HttpEvent < any >> {

        console.log("intercepted request ... ");

        // Clone the request to add the new header.
        const authReq = req.clone({
            headers: req.headers.set("headerName", "headerValue")
        });

        console.log("Sending request with new header now ...");

        //send the newly created request
        return next.handle(authReq)
            .catch((error, caught) => {
                //intercept the respons error and displace it to the console
                console.log("Error Occurred");
                console.log(error);
                //return the error to the method that called it
                return Observable.throw(error);
            }) as any;
    }
}