Move URL transform methods from ServerHttpResponse to ServerWebExchange

This commit moves `encodeUrl` and `registerUrlEncoder` from
ServerHttpResponse to ServerWebExchange.

It also renames `encodeUrl` to `transformUrl` and `registerUrlEncoder`
to `addUrlTransformer` to make it clearer that these methods do not
perform actual URL encodings (i.e. they do not replaceinvalid
characters).
The `add` prefix (instead of `register`) makes it clearer that each
function is added in addition to the previous one.

Issue: SPR-15924

spring-web/src/main/java/org/springframework/http/server/reactive/AbstractServerHttpResponse.java

@@ -19,7 +19,6 @@ package org.springframework.http.server.reactive;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.atomic.AtomicReference;
-import java.util.function.Function;
 import java.util.function.Supplier;
 import java.util.stream.Collectors;
 
@@ -69,9 +68,6 @@ public abstract class AbstractServerHttpResponse implements ServerHttpResponse {
 
 	private final MultiValueMap<String, ResponseCookie> cookies;
 
-	@Nullable
-	private Function<String, String> urlEncoder = url -> url;
-
 	private final AtomicReference<State> state = new AtomicReference<>(State.NEW);
 
 	private final List<Supplier<? extends Mono<Void>>> commitActions = new ArrayList<>(4);
@@ -136,16 +132,6 @@ public abstract class AbstractServerHttpResponse implements ServerHttpResponse {
 		}
 	}
 
-	@Override
-	public String encodeUrl(String url) {
-		return (this.urlEncoder != null ? this.urlEncoder.apply(url) : url);
-	}
-
-	@Override
-	public void registerUrlEncoder(Function<String, String> encoder) {
-		this.urlEncoder = (this.urlEncoder != null ? this.urlEncoder.andThen(encoder) : encoder);
-	}
-
 	@Override
 	public void beforeCommit(Supplier<? extends Mono<Void>> action) {
 		this.commitActions.add(action);

spring-web/src/main/java/org/springframework/http/server/reactive/ServerHttpResponse.java

@@ -16,8 +16,6 @@
 
 package org.springframework.http.server.reactive;
 
-import java.util.function.Function;
-
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ReactiveHttpOutputMessage;
 import org.springframework.http.ResponseCookie;
@@ -59,22 +57,4 @@ public interface ServerHttpResponse extends ReactiveHttpOutputMessage {
 	 */
 	void addCookie(ResponseCookie cookie);
 
-	/**
-	 * A mechanism for URL rewriting that applications and libraries such as
-	 * HTML template libraries to use consistently for all URLs emitted by
-	 * the application. Doing so enables the registration of URL encoders via
-	 * {@link #registerUrlEncoder} that can insert an id for authentication,
-	 * a nonce for CSRF protection, or other.
-	 * @param url the URL to encode
-	 * @return the encoded URL or the same
-	 */
-	String encodeUrl(String url);
-
-	/**
-	 * Register a URL rewriting function for use with {@link #encodeUrl}.
-	 * The function must return an encoded URL or the same URL.
-	 * @param encoder a URL encoding function to use
-	 */
-	void registerUrlEncoder(Function<String, String> encoder);
-
 }

spring-web/src/main/java/org/springframework/http/server/reactive/ServerHttpResponseDecorator.java

@@ -15,7 +15,6 @@
  */
 package org.springframework.http.server.reactive;
 
-import java.util.function.Function;
 import java.util.function.Supplier;
 
 import org.reactivestreams.Publisher;
@@ -80,16 +79,6 @@ public class ServerHttpResponseDecorator implements ServerHttpResponse {
 		getDelegate().addCookie(cookie);
 	}
 
-	@Override
-	public String encodeUrl(String url) {
-		return getDelegate().encodeUrl(url);
-	}
-
-	@Override
-	public void registerUrlEncoder(Function<String, String> encoder) {
-		getDelegate().registerUrlEncoder(encoder);
-	}
-
 	@Override
 	public DataBufferFactory bufferFactory() {
 		return getDelegate().bufferFactory();

spring-web/src/main/java/org/springframework/web/server/ServerWebExchange.java

@@ -20,6 +20,7 @@ import java.security.Principal;
 import java.time.Instant;
 import java.util.Map;
 import java.util.function.Consumer;
+import java.util.function.Function;
 
 import reactor.core.publisher.Mono;
 
@@ -177,6 +178,23 @@ public interface ServerWebExchange {
 	 */
 	boolean checkNotModified(@Nullable String etag, Instant lastModified);
 
+	/**
+	 * Transform the given url according to the registered transformation function(s).
+	 * By default, this method returns the given {@code url}, though additional
+	 * transformation functions can by registered with {@link #addUrlTransformer}
+	 * @param url the URL to transform
+	 * @return the transformed URL
+	 */
+	String transformUrl(String url);
+
+	/**
+	 * Register an additional URL transformation function for use with {@link #transformUrl}.
+	 * The given function can be used to insert an id for authentication, a nonce for CSRF
+	 * protection, etc.
+	 * <p>Note that the given function is applied after any previously registered functions.
+	 * @param transformer a URL transformation function to add
+	 */
+	void addUrlTransformer(Function<String, String> transformer);
 
 	/**
 	 * Return a builder to mutate properties of this exchange by wrapping it

spring-web/src/main/java/org/springframework/web/server/ServerWebExchangeDecorator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -18,6 +18,7 @@ package org.springframework.web.server;
 import java.security.Principal;
 import java.time.Instant;
 import java.util.Map;
+import java.util.function.Function;
 
 import reactor.core.publisher.Mono;
 
@@ -120,6 +121,15 @@ public class ServerWebExchangeDecorator implements ServerWebExchange {
 		return getDelegate().checkNotModified(etag, lastModified);
 	}
 
+	@Override
+	public String transformUrl(String url) {
+		return getDelegate().transformUrl(url);
+	}
+
+	@Override
+	public void addUrlTransformer(Function<String, String> transformer) {
+		getDelegate().addUrlTransformer(transformer);
+	}
 
 	@Override
 	public String toString() {

spring-web/src/main/java/org/springframework/web/server/adapter/DefaultServerWebExchange.java

@@ -24,6 +24,7 @@ import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.function.Function;
 
 import reactor.core.publisher.Mono;
 
@@ -91,6 +92,8 @@ public class DefaultServerWebExchange implements ServerWebExchange {
 
 	private volatile boolean notModified;
 
+	private Function<String, String> urlTransformer = url -> url;
+
 
 	public DefaultServerWebExchange(ServerHttpRequest request, ServerHttpResponse response,
 			WebSessionManager sessionManager, ServerCodecConfigurer codecConfigurer, LocaleContextResolver localeContextResolver) {
@@ -322,4 +325,16 @@ public class DefaultServerWebExchange implements ServerWebExchange {
 		return true;
 	}
 
+	@Override
+	public String transformUrl(String url) {
+		return this.urlTransformer.apply(url);
+	}
+
+	@Override
+	public void addUrlTransformer(Function<String, String> transformer) {
+		Assert.notNull(transformer, "'encoder' must not be null");
+		this.urlTransformer = this.urlTransformer.andThen(transformer);
+	}
+
+
 }