Cache encoded BASIC credentials in ExchangeFilterFunctions

Prior to this commit, the Basic Authentication credentials were encoded for
each request in ExchangeFilterFunctions.basicAuthentication(String, String).

This commit addresses this minor performance issue by encoding the
credentials prior to the creation of the lambda expression returned by
ExchangeFilterFunctions.basicAuthentication(String, String).

Closes gh-23256

Author: sbrannen

spring-webflux/src/main/java/org/springframework/web/reactive/function/client/ExchangeFilterFunctions.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -39,6 +39,7 @@
  *
  * @author Rob Winch
  * @author Arjen Poutsma
+ * @author Sam Brannen
  * @since 5.0
  */
 public abstract class ExchangeFilterFunctions {
@@ -90,21 +91,22 @@ public static ExchangeFilterFunction statusError(Predicate<HttpStatus> statusPre
 
 	/**
 	 * Return a filter that applies HTTP Basic Authentication to the request
-	 * headers via {@link HttpHeaders#setBasicAuth(String, String)}.
-	 * @param user the user
+	 * headers via {@link HttpHeaders#setBasicAuth(String)} and
+	 * {@link HttpHeaders#encodeBasicAuth(String, String, Charset)}.
+	 * @param username the username
 	 * @param password the password
 	 * @return the filter to add authentication headers with
-	 * @see HttpHeaders#setBasicAuth(String, String)
-	 * @see HttpHeaders#setBasicAuth(String, String, Charset)
+	 * @see HttpHeaders#encodeBasicAuth(String, String, Charset)
+	 * @see HttpHeaders#setBasicAuth(String)
 	 */
-	public static ExchangeFilterFunction basicAuthentication(String user, String password) {
+	public static ExchangeFilterFunction basicAuthentication(String username, String password) {
+		String encodedCredentials = HttpHeaders.encodeBasicAuth(username, password, null);
 		return (request, next) ->
 				next.exchange(ClientRequest.from(request)
-						.headers(headers -> headers.setBasicAuth(user, password))
+						.headers(headers -> headers.setBasicAuth(encodedCredentials))
 						.build());
 	}
 
-
 	/**
 	 * Variant of {@link #basicAuthentication(String, String)} that looks up
 	 * the {@link Credentials Credentials} in a
@@ -132,7 +134,7 @@ public static ExchangeFilterFunction basicAuthentication() {
 
 
 	/**
-	 * Stores user and password for HTTP basic authentication.
+	 * Stores username and password for HTTP basic authentication.
 	 * @deprecated as of Spring 5.1 in favor of using
 	 * {@link HttpHeaders#setBasicAuth(String, String)} while building the request.
 	 */
@@ -156,18 +158,18 @@ public Credentials(String username, String password) {
 		}
 
 		/**
-		 * Return a {@literal Consumer} that stores the given user and password
+		 * Return a {@literal Consumer} that stores the given username and password
 		 * as a request attribute of type {@code Credentials} that is in turn
 		 * used by {@link ExchangeFilterFunctions#basicAuthentication()}.
-		 * @param user the user
+		 * @param username the username
 		 * @param password the password
 		 * @return a consumer that can be passed into
 		 * {@linkplain ClientRequest.Builder#attributes(java.util.function.Consumer)}
 		 * @see ClientRequest.Builder#attributes(java.util.function.Consumer)
 		 * @see #BASIC_AUTHENTICATION_CREDENTIALS_ATTRIBUTE
 		 */
-		public static Consumer<Map<String, Object>> basicAuthenticationCredentials(String user, String password) {
-			Credentials credentials = new Credentials(user, password);
+		public static Consumer<Map<String, Object>> basicAuthenticationCredentials(String username, String password) {
+			Credentials credentials = new Credentials(username, password);
 			return (map -> map.put(BASIC_AUTHENTICATION_CREDENTIALS_ATTRIBUTE, credentials));
 		}