Provide simple way to create ClientResponse

This commit introduces ClientResponse.Builder, an easier way to create a
ClientResponse from an existing response, or from scratch.

Issue: SPR-16553

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -16,20 +16,26 @@
 
 package org.springframework.web.reactive.function.client;
 
+import java.util.Collections;
 import java.util.List;
 import java.util.Optional;
 import java.util.OptionalLong;
+import java.util.function.Consumer;
 
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
 
 import org.springframework.core.ParameterizedTypeReference;
+import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
 import org.springframework.http.ResponseCookie;
 import org.springframework.http.ResponseEntity;
 import org.springframework.http.client.reactive.ClientHttpResponse;
+import org.springframework.http.codec.HttpMessageReader;
+import org.springframework.http.codec.HttpMessageWriter;
+import org.springframework.util.Assert;
 import org.springframework.util.MultiValueMap;
 import org.springframework.web.reactive.function.BodyExtractor;
 
@@ -68,6 +74,11 @@ public interface ClientResponse {
 	 */
 	MultiValueMap<String, ResponseCookie> cookies();
 
+	/**
+	 * Return the strategies used to convert the body of this response.
+	 */
+	ExchangeStrategies strategies();
+
 	/**
 	 * Extract the body with the given {@code BodyExtractor}.
 	 * @param extractor the {@code BodyExtractor} that reads from the response
@@ -141,6 +152,66 @@ public interface ClientResponse {
 	<T> Mono<ResponseEntity<List<T>>> toEntityList(ParameterizedTypeReference<T> typeReference);
 
 
+	// Static builder methods
+
+	/**
+	 * Create a builder with the status, headers, and cookies of the given response.
+	 * @param other the response to copy the status, headers, and cookies from
+	 * @return the created builder
+	 */
+	static Builder from(ClientResponse other) {
+		Assert.notNull(other, "'other' must not be null");
+		return new DefaultClientResponseBuilder(other);
+	}
+
+	/**
+	 * Create a response builder with the given status code and using default strategies for reading
+	 * the body.
+	 * @param statusCode the status code
+	 * @return the created builder
+	 */
+	static Builder create(HttpStatus statusCode) {
+		return create(statusCode, ExchangeStrategies.withDefaults());
+	}
+
+	/**
+	 * Create a response builder with the given status code and strategies for reading the body.
+	 * @param statusCode the status code
+	 * @param strategies the strategies
+	 * @return the created builder
+	 */
+	static Builder create(HttpStatus statusCode, ExchangeStrategies strategies) {
+		Assert.notNull(statusCode, "'statusCode' must not be null");
+		Assert.notNull(strategies, "'strategies' must not be null");
+		return new DefaultClientResponseBuilder(strategies)
+				.statusCode(statusCode);
+	}
+
+	/**
+	 * Create a response builder with the given status code and message body readers.
+	 * @param statusCode the status code
+	 * @param messageReaders the message readers
+	 * @return the created builder
+	 */
+	static Builder create(HttpStatus statusCode, List<HttpMessageReader<?>> messageReaders) {
+		Assert.notNull(statusCode, "'statusCode' must not be null");
+		Assert.notNull(messageReaders, "'messageReaders' must not be null");
+
+		return create(statusCode, new ExchangeStrategies() {
+			@Override
+			public List<HttpMessageReader<?>> messageReaders() {
+				return messageReaders;
+			}
+
+			@Override
+			public List<HttpMessageWriter<?>> messageWriters() {
+				// not used in the response
+				return Collections.emptyList();
+			}
+		});
+
+	}
+
 	/**
 	 * Represents the headers of the HTTP response.
 	 * @see ClientResponse#headers()
@@ -172,4 +243,80 @@ public interface ClientResponse {
 		HttpHeaders asHttpHeaders();
 	}
 
+	/**
+	 * Defines a builder for a response.
+	 */
+	interface Builder {
+
+		/**
+		 * Set the status code of the response.
+		 * @param statusCode the new status code.
+		 * @return this builder
+		 */
+		Builder statusCode(HttpStatus statusCode);
+
+		/**
+		 * Add the given header value(s) under the given name.
+		 * @param headerName  the header name
+		 * @param headerValues the header value(s)
+		 * @return this builder
+		 * @see HttpHeaders#add(String, String)
+		 */
+		Builder header(String headerName, String... headerValues);
+
+		/**
+		 * Manipulate this response's headers with the given consumer. The
+		 * headers provided to the consumer are "live", so that the consumer can be used to
+		 * {@linkplain HttpHeaders#set(String, String) overwrite} existing header values,
+		 * {@linkplain HttpHeaders#remove(Object) remove} values, or use any of the other
+		 * {@link HttpHeaders} methods.
+		 * @param headersConsumer a function that consumes the {@code HttpHeaders}
+		 * @return this builder
+		 */
+		Builder headers(Consumer<HttpHeaders> headersConsumer);
+
+		/**
+		 * Add a cookie with the given name and value(s).
+		 * @param name the cookie name
+		 * @param values the cookie value(s)
+		 * @return this builder
+		 */
+		Builder cookie(String name, String... values);
+
+		/**
+		 * Manipulate this response's cookies with the given consumer. The
+		 * map provided to the consumer is "live", so that the consumer can be used to
+		 * {@linkplain MultiValueMap#set(Object, Object) overwrite} existing header values,
+		 * {@linkplain MultiValueMap#remove(Object) remove} values, or use any of the other
+		 * {@link MultiValueMap} methods.
+		 * @param cookiesConsumer a function that consumes the cookies map
+		 * @return this builder
+		 */
+		Builder cookies(Consumer<MultiValueMap<String, ResponseCookie>> cookiesConsumer);
+
+		/**
+		 * Sets the body of the response. Calling this methods will
+		 * {@linkplain org.springframework.core.io.buffer.DataBufferUtils#release(DataBuffer) release}
+		 * the existing body of the builder.
+		 * @param body the new body.
+		 * @return this builder
+		 */
+		Builder body(Flux<DataBuffer> body);
+
+		/**
+		 * Sets the body of the response to the UTF-8 encoded bytes of the given string.
+		 * Calling this methods will
+		 * {@linkplain org.springframework.core.io.buffer.DataBufferUtils#release(DataBuffer) release}
+		 * the existing body of the builder.
+		 * @param body the new body.
+		 * @return this builder
+		 */
+		Builder body(String body);
+
+		/**
+		 * Builds the response.
+		 * @return the response
+		 */
+		ClientResponse build();
+	}
 }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -61,6 +61,10 @@ class DefaultClientResponse implements ClientResponse {
 		this.headers = new DefaultHeaders();
 	}
 
+	@Override
+	public ExchangeStrategies strategies() {
+		return this.strategies;
+	}
 
 	@Override
 	public HttpStatus statusCode() {

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

@@ -0,0 +1,189 @@
+/*
+ * Copyright 2002-2018 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.web.reactive.function.client;
+
+import java.nio.charset.StandardCharsets;
+import java.util.function.Consumer;
+
+import reactor.core.publisher.Flux;
+
+import org.springframework.core.io.buffer.DataBuffer;
+import org.springframework.core.io.buffer.DataBufferFactory;
+import org.springframework.core.io.buffer.DataBufferUtils;
+import org.springframework.core.io.buffer.DefaultDataBufferFactory;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseCookie;
+import org.springframework.http.client.reactive.ClientHttpResponse;
+import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
+import org.springframework.util.CollectionUtils;
+import org.springframework.util.LinkedMultiValueMap;
+import org.springframework.util.MultiValueMap;
+
+/**
+ * Default implementation of {@link ClientResponse.Builder}.
+ *
+ * @author Arjen Poutsma
+ * @since 5.0.5
+ */
+class DefaultClientResponseBuilder implements ClientResponse.Builder {
+
+	private final HttpHeaders headers = new HttpHeaders();
+
+	private final MultiValueMap<String, ResponseCookie> cookies = new LinkedMultiValueMap<>();
+
+	private HttpStatus statusCode = HttpStatus.OK;
+
+	private Flux<DataBuffer> body = Flux.empty();
+
+	private ExchangeStrategies strategies;
+
+
+	public DefaultClientResponseBuilder(ExchangeStrategies strategies) {
+		Assert.notNull(strategies, "'strategies' must not be null");
+		this.strategies = strategies;
+	}
+
+	public DefaultClientResponseBuilder(ClientResponse other) {
+		this(other.strategies());
+		statusCode(other.statusCode());
+		headers(headers -> headers.addAll(other.headers().asHttpHeaders()));
+		cookies(cookies -> cookies.addAll(other.cookies()));
+	}
+
+	@Override
+	public DefaultClientResponseBuilder statusCode(HttpStatus statusCode) {
+		Assert.notNull(statusCode, "'statusCode' must not be null");
+		this.statusCode = statusCode;
+		return this;
+	}
+
+	@Override
+	public ClientResponse.Builder header(String headerName, String... headerValues) {
+		for (String headerValue : headerValues) {
+			this.headers.add(headerName, headerValue);
+		}
+		return this;
+	}
+
+	@Override
+	public ClientResponse.Builder headers(Consumer<HttpHeaders> headersConsumer) {
+		Assert.notNull(headersConsumer, "'headersConsumer' must not be null");
+		headersConsumer.accept(this.headers);
+		return this;
+	}
+
+	@Override
+	public DefaultClientResponseBuilder cookie(String name, String... values) {
+		for (String value : values) {
+			this.cookies.add(name, ResponseCookie.from(name, value).build());
+		}
+		return this;
+	}
+
+	@Override
+	public ClientResponse.Builder cookies(
+			Consumer<MultiValueMap<String, ResponseCookie>> cookiesConsumer) {
+		Assert.notNull(cookiesConsumer, "'cookiesConsumer' must not be null");
+		cookiesConsumer.accept(this.cookies);
+		return this;
+	}
+
+	@Override
+	public ClientResponse.Builder body(Flux<DataBuffer> body) {
+		Assert.notNull(body, "'body' must not be null");
+		releaseBody();
+		this.body = body;
+		return this;
+	}
+
+	@Override
+	public ClientResponse.Builder body(String body) {
+		Assert.notNull(body, "'body' must not be null");
+		releaseBody();
+		DataBufferFactory dataBufferFactory = new DefaultDataBufferFactory();
+		this.body = Flux.just(body).
+				map(s -> {
+					byte[] bytes = body.getBytes(StandardCharsets.UTF_8);
+					return dataBufferFactory.wrap(bytes);
+				});
+		return this;
+	}
+
+	private void releaseBody() {
+		this.body.subscribe(DataBufferUtils.releaseConsumer());
+	}
+
+	@Override
+	public ClientResponse build() {
+		ClientHttpResponse clientHttpResponse = new BuiltClientHttpResponse(this.statusCode,
+				this.headers, this.cookies, this.body);
+		return new DefaultClientResponse(clientHttpResponse, this.strategies);
+	}
+
+	private static class BuiltClientHttpResponse implements ClientHttpResponse {
+
+		private final HttpStatus statusCode;
+
+		private final HttpHeaders headers;
+
+		private final MultiValueMap<String, ResponseCookie> cookies;
+
+		private final Flux<DataBuffer> body;
+
+		public BuiltClientHttpResponse(HttpStatus statusCode, HttpHeaders headers,
+				MultiValueMap<String, ResponseCookie> cookies,
+				Flux<DataBuffer> body) {
+
+			this.statusCode = statusCode;
+			this.headers = HttpHeaders.readOnlyHttpHeaders(headers);
+			this.cookies = unmodifiableCopy(cookies);
+			this.body = body;
+		}
+
+		private static @Nullable <K, V> MultiValueMap<K, V> unmodifiableCopy(@Nullable MultiValueMap<K, V> original) {
+			if (original != null) {
+				return CollectionUtils.unmodifiableMultiValueMap(new LinkedMultiValueMap<>(original));
+			}
+			else {
+				return null;
+			}
+		}
+
+		@Override
+		public HttpStatus getStatusCode() {
+			return this.statusCode;
+		}
+
+		@Override
+		public HttpHeaders getHeaders() {
+			return this.headers;
+		}
+
+		@Override
+		public MultiValueMap<String, ResponseCookie> getCookies() {
+			return this.cookies;
+		}
+
+		@Override
+		public Flux<DataBuffer> getBody() {
+			return this.body;
+		}
+	}
+
+}

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

@@ -0,0 +1,176 @@
+/*
+ * Copyright 2002-2018 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.web.reactive.function.client.support;
+
+import java.util.List;
+import java.util.Optional;
+import java.util.OptionalLong;
+
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.Mono;
+
+import org.springframework.core.ParameterizedTypeReference;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.MediaType;
+import org.springframework.http.ResponseCookie;
+import org.springframework.http.ResponseEntity;
+import org.springframework.http.client.reactive.ClientHttpResponse;
+import org.springframework.util.Assert;
+import org.springframework.util.MultiValueMap;
+import org.springframework.web.reactive.function.BodyExtractor;
+import org.springframework.web.reactive.function.client.ClientResponse;
+import org.springframework.web.reactive.function.client.ExchangeStrategies;
+
+/**
+ * Implementation of the {@link ClientResponse} interface that can be subclassed
+ * to adapt the request in a
+ * {@link org.springframework.web.reactive.function.client.ExchangeFilterFunction exchange filter function}.
+ * All methods default to calling through to the wrapped request.
+ *
+ * @author Arjen Poutsma
+ * @since 5.0.5
+ */
+public class ClientResponseWrapper implements ClientResponse {
+
+	private final ClientResponse delegate;
+
+
+	/**
+	 * Create a new {@code ClientResponseWrapper} that wraps the given response.
+	 * @param delegate the response to wrap
+	 */
+	public ClientResponseWrapper(ClientResponse delegate) {
+		Assert.notNull(delegate, "'delegate' must not be null");
+		this.delegate = delegate;
+	}
+
+
+	/**
+	 * Return the wrapped request.
+	 */
+	public ClientResponse response() {
+		return this.delegate;
+	}
+
+	@Override
+	public ExchangeStrategies strategies() {
+		return this.delegate.strategies();
+	}
+
+	@Override
+	public HttpStatus statusCode() {
+		return this.delegate.statusCode();
+	}
+
+	@Override
+	public Headers headers() {
+		return this.delegate.headers();
+	}
+
+	@Override
+	public MultiValueMap<String, ResponseCookie> cookies() {
+		return this.delegate.cookies();
+	}
+
+	@Override
+	public <T> T body(BodyExtractor<T, ? super ClientHttpResponse> extractor) {
+		return this.delegate.body(extractor);
+	}
+
+	@Override
+	public <T> Mono<T> bodyToMono(Class<? extends T> elementClass) {
+		return this.delegate.bodyToMono(elementClass);
+	}
+
+	@Override
+	public <T> Mono<T> bodyToMono(ParameterizedTypeReference<T> typeReference) {
+		return this.delegate.bodyToMono(typeReference);
+	}
+
+	@Override
+	public <T> Flux<T> bodyToFlux(Class<? extends T> elementClass) {
+		return this.delegate.bodyToFlux(elementClass);
+	}
+
+	@Override
+	public <T> Flux<T> bodyToFlux(ParameterizedTypeReference<T> typeReference) {
+		return this.delegate.bodyToFlux(typeReference);
+	}
+
+	@Override
+	public <T> Mono<ResponseEntity<T>> toEntity(Class<T> bodyType) {
+		return this.delegate.toEntity(bodyType);
+	}
+
+	@Override
+	public <T> Mono<ResponseEntity<T>> toEntity(ParameterizedTypeReference<T> typeReference) {
+		return this.delegate.toEntity(typeReference);
+	}
+
+	@Override
+	public <T> Mono<ResponseEntity<List<T>>> toEntityList(Class<T> elementType) {
+		return this.delegate.toEntityList(elementType);
+	}
+
+	@Override
+	public <T> Mono<ResponseEntity<List<T>>> toEntityList(ParameterizedTypeReference<T> typeReference) {
+		return this.delegate.toEntityList(typeReference);
+	}
+
+	/**
+	 * Implementation of the {@code Headers} interface that can be subclassed
+	  * to adapt the headers in a
+	  * {@link org.springframework.web.reactive.function.client.ExchangeFilterFunction exchange filter function}.
+	  * All methods default to calling through to the wrapped request.
+	 */
+	public static class HeadersWrapper implements ClientResponse.Headers {
+
+		private final Headers headers;
+
+
+		/**
+		 * Create a new {@code HeadersWrapper} that wraps the given request.
+		 * @param headers the headers to wrap
+		 */
+		public HeadersWrapper(Headers headers) {
+			this.headers = headers;
+		}
+
+
+		@Override
+		public OptionalLong contentLength() {
+			return this.headers.contentLength();
+		}
+
+		@Override
+		public Optional<MediaType> contentType() {
+			return this.headers.contentType();
+		}
+
+		@Override
+		public List<String> header(String headerName) {
+			return this.headers.header(headerName);
+		}
+
+		@Override
+		public HttpHeaders asHttpHeaders() {
+			return this.headers.asHttpHeaders();
+		}
+	}
+
+}

spring-webflux/src/main/java/org/springframework/web/reactive/function/client/support/package-info.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2002-2018 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Classes supporting the {@code org.springframework.web.reactive.function.client} package.
+ * Contains a {@code ClientResponse} wrapper to adapt a request.
+ */
+@NonNullApi
+@NonNullFields
+package org.springframework.web.reactive.function.client.support;
+
+import org.springframework.lang.NonNullApi;
+import org.springframework.lang.NonNullFields;

spring-webflux/src/main/java/org/springframework/web/reactive/function/server/support/ServerRequestWrapper.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -40,14 +40,14 @@ import org.springframework.http.server.reactive.ServerHttpRequest;
 import org.springframework.util.Assert;
 import org.springframework.util.MultiValueMap;
 import org.springframework.web.reactive.function.BodyExtractor;
-import org.springframework.web.reactive.function.server.HandlerFunction;
 import org.springframework.web.reactive.function.server.ServerRequest;
 import org.springframework.web.server.WebSession;
 import org.springframework.web.util.UriBuilder;
 
 /**
  * Implementation of the {@link ServerRequest} interface that can be subclassed
- * to adapt the request to a {@link HandlerFunction handler function}.
+ * to adapt the request in a
+ * {@link org.springframework.web.reactive.function.server.HandlerFilterFunction handler filter function}.
  * All methods default to calling through to the wrapped request.
  *
  * @author Arjen Poutsma
@@ -59,7 +59,7 @@ public class ServerRequestWrapper implements ServerRequest {
 
 
 	/**
-	 * Create a new {@code RequestWrapper} that wraps the given request.
+	 * Create a new {@code ServerRequestWrapper} that wraps the given request.
 	 * @param delegate the request to wrap
 	 */
 	public ServerRequestWrapper(ServerRequest delegate) {
@@ -187,13 +187,15 @@ public class ServerRequestWrapper implements ServerRequest {
 
 	/**
 	 * Implementation of the {@code Headers} interface that can be subclassed
-	 * to adapt the headers to a {@link HandlerFunction handler function}.
+	 * to adapt the headers in a
+	 * {@link org.springframework.web.reactive.function.server.HandlerFilterFunction handler filter function}.
 	 * All methods default to calling through to the wrapped headers.
 	 */
 	public static class HeadersWrapper implements ServerRequest.Headers {
 
 		private final Headers headers;
 
+
 		/**
 		 * Create a new {@code HeadersWrapper} that wraps the given request.
 		 * @param headers the headers to wrap
@@ -203,6 +205,7 @@ public class ServerRequestWrapper implements ServerRequest {
 			this.headers = headers;
 		}
 
+
 		@Override
 		public List<MediaType> accept() {
 			return this.headers.accept();

spring-webflux/src/main/java/org/springframework/web/reactive/function/server/support/package-info.java

@@ -1,5 +1,5 @@
 /**
- * Classes supporting the {@code org.springframework.web.reactive.function} package.
+ * Classes supporting the {@code org.springframework.web.reactive.function.server} package.
  * Contains a {@code HandlerAdapter} that supports {@code HandlerFunction}s,
  * a {@code HandlerResultHandler} that supports {@code ServerResponse}s, and
  * a {@code ServerRequest} wrapper to adapt a request.