Add HttpRequestBuilder default implementation

This commit adds a `DefaultHttpRequestBuilder` and its companion static
builders in `HttpRequestBuilders`. This allows to build client requests
with a friendly builder API, inspired by Spring's MockMvc API.

spring-web-reactive/src/main/java/org/springframework/web/client/reactive/DefaultHttpRequestBuilder.java

@@ -0,0 +1,167 @@
+/*
+ * Copyright 2002-2016 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.client.reactive;
+
+
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Optional;
+import java.util.stream.Collectors;
+
+import org.reactivestreams.Publisher;
+import reactor.core.publisher.Flux;
+
+import org.springframework.core.ResolvableType;
+import org.springframework.core.codec.Encoder;
+import org.springframework.http.HttpCookie;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpMethod;
+import org.springframework.http.MediaType;
+import org.springframework.http.client.reactive.ClientHttpRequest;
+import org.springframework.http.client.reactive.ClientHttpRequestFactory;
+import org.springframework.web.client.RestClientException;
+
+/**
+ * Builds a {@link ClientHttpRequest}
+ *
+ * <p>See static factory methods in {@link HttpRequestBuilders}
+ *
+ * @author Brian Clozel
+ * @see HttpRequestBuilders
+ */
+public class DefaultHttpRequestBuilder implements HttpRequestBuilder {
+
+	protected HttpMethod httpMethod;
+
+	protected HttpHeaders httpHeaders;
+
+	protected URI url;
+
+	protected Flux contentPublisher;
+
+	protected List<Encoder<?>> messageEncoders;
+
+	protected final List<HttpCookie> cookies = new ArrayList<HttpCookie>();
+
+	protected DefaultHttpRequestBuilder() {
+	}
+
+	public DefaultHttpRequestBuilder(HttpMethod httpMethod, String urlTemplate, Object... urlVariables) throws RestClientException {
+		this.httpMethod = httpMethod;
+		this.httpHeaders = new HttpHeaders();
+		this.url = parseURI(urlTemplate);
+	}
+
+	public DefaultHttpRequestBuilder(HttpMethod httpMethod, URI url) {
+		this.httpMethod = httpMethod;
+		this.httpHeaders = new HttpHeaders();
+		this.url = url;
+	}
+
+	protected DefaultHttpRequestBuilder setMessageEncoders(List<Encoder<?>> messageEncoders) {
+		this.messageEncoders = messageEncoders;
+		return this;
+	}
+
+	private URI parseURI(String uri) throws RestClientException {
+		try {
+			return new URI(uri);
+		}
+		catch (URISyntaxException e) {
+			throw new RestClientException("could not parse URL template", e);
+		}
+	}
+
+	public DefaultHttpRequestBuilder param(String name, String... values) {
+		return this;
+	}
+
+	public DefaultHttpRequestBuilder header(String name, String... values) {
+		Arrays.stream(values).forEach(value -> this.httpHeaders.add(name, value));
+		return this;
+	}
+
+	public DefaultHttpRequestBuilder headers(HttpHeaders httpHeaders) {
+		this.httpHeaders = httpHeaders;
+		return this;
+	}
+
+	public DefaultHttpRequestBuilder contentType(MediaType contentType) {
+		this.httpHeaders.setContentType(contentType);
+		return this;
+	}
+
+	public DefaultHttpRequestBuilder contentType(String contentType) {
+		this.httpHeaders.setContentType(MediaType.parseMediaType(contentType));
+		return this;
+	}
+
+	public DefaultHttpRequestBuilder accept(MediaType... mediaTypes) {
+		this.httpHeaders.setAccept(Arrays.asList(mediaTypes));
+		return this;
+	}
+
+	public DefaultHttpRequestBuilder accept(String... mediaTypes) {
+		this.httpHeaders.setAccept(Arrays.stream(mediaTypes)
+				.map(type -> MediaType.parseMediaType(type))
+				.collect(Collectors.toList()));
+		return this;
+	}
+
+	public DefaultHttpRequestBuilder content(Object content) {
+		this.contentPublisher = Flux.just(content);
+		return this;
+	}
+
+	public DefaultHttpRequestBuilder contentStream(Publisher content) {
+		this.contentPublisher = Flux.from(content);
+		return this;
+	}
+
+	public ClientHttpRequest build(ClientHttpRequestFactory factory) {
+		ClientHttpRequest request = factory.createRequest(this.httpMethod, this.url, this.httpHeaders);
+		request.getHeaders().putAll(this.httpHeaders);
+
+		if (this.contentPublisher != null) {
+			ResolvableType requestBodyType = ResolvableType.forInstance(this.contentPublisher);
+			MediaType mediaType = request.getHeaders().getContentType();
+
+			Optional<Encoder<?>> messageEncoder = resolveEncoder(requestBodyType, mediaType);
+
+			if (messageEncoder.isPresent()) {
+				request.setBody(messageEncoder.get().encode(this.contentPublisher, requestBodyType, mediaType));
+			}
+			else {
+				// TODO: wrap with client exception?
+				request.setBody(Flux.error(new IllegalStateException("Can't write request body" +
+						"of type '" + requestBodyType.toString() +
+						"' for content-type '" + mediaType.toString() + "'")));
+			}
+		}
+
+		return request;
+	}
+
+	protected Optional<Encoder<?>> resolveEncoder(ResolvableType type, MediaType mediaType) {
+		return this.messageEncoders.stream()
+				.filter(e -> e.canEncode(type, mediaType)).findFirst();
+	}
+
+}

spring-web-reactive/src/main/java/org/springframework/web/client/reactive/HttpRequestBuilder.java

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-package org.springframework.web.client;
+package org.springframework.web.client.reactive;
 
 import org.springframework.http.client.reactive.ClientHttpRequest;
 import org.springframework.http.client.reactive.ClientHttpRequestFactory;

spring-web-reactive/src/main/java/org/springframework/web/client/reactive/HttpRequestBuilders.java

@@ -0,0 +1,110 @@
+/*
+ * Copyright 2002-2016 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.client.reactive;
+
+import org.springframework.http.HttpMethod;
+
+/**
+ * Static factory methods for {@link DefaultHttpRequestBuilder RequestBuilders}.
+ *
+ * @author Brian Clozel
+ */
+public abstract class HttpRequestBuilders {
+
+	/**
+	 * Create a {@link DefaultHttpRequestBuilder} for a GET request.
+	 *
+	 * @param urlTemplate  a URL template; the resulting URL will be encoded
+	 * @param urlVariables zero or more URL variables
+	 */
+	public static DefaultHttpRequestBuilder get(String urlTemplate, Object... urlVariables) {
+		return new DefaultHttpRequestBuilder(HttpMethod.GET, urlTemplate, urlVariables);
+	}
+
+	/**
+	 * Create a {@link DefaultHttpRequestBuilder} for a POST request.
+	 *
+	 * @param urlTemplate  a URL template; the resulting URL will be encoded
+	 * @param urlVariables zero or more URL variables
+	 */
+	public static DefaultHttpRequestBuilder post(String urlTemplate, Object... urlVariables) {
+		return new DefaultHttpRequestBuilder(HttpMethod.POST, urlTemplate, urlVariables);
+	}
+
+
+	/**
+	 * Create a {@link DefaultHttpRequestBuilder} for a PUT request.
+	 *
+	 * @param urlTemplate  a URL template; the resulting URL will be encoded
+	 * @param urlVariables zero or more URL variables
+	 */
+	public static DefaultHttpRequestBuilder put(String urlTemplate, Object... urlVariables) {
+		return new DefaultHttpRequestBuilder(HttpMethod.PUT, urlTemplate, urlVariables);
+	}
+
+	/**
+	 * Create a {@link DefaultHttpRequestBuilder} for a PATCH request.
+	 *
+	 * @param urlTemplate  a URL template; the resulting URL will be encoded
+	 * @param urlVariables zero or more URL variables
+	 */
+	public static DefaultHttpRequestBuilder patch(String urlTemplate, Object... urlVariables) {
+		return new DefaultHttpRequestBuilder(HttpMethod.PATCH, urlTemplate, urlVariables);
+	}
+
+	/**
+	 * Create a {@link DefaultHttpRequestBuilder} for a DELETE request.
+	 *
+	 * @param urlTemplate  a URL template; the resulting URL will be encoded
+	 * @param urlVariables zero or more URL variables
+	 */
+	public static DefaultHttpRequestBuilder delete(String urlTemplate, Object... urlVariables) {
+		return new DefaultHttpRequestBuilder(HttpMethod.DELETE, urlTemplate, urlVariables);
+	}
+
+	/**
+	 * Create a {@link DefaultHttpRequestBuilder} for an OPTIONS request.
+	 *
+	 * @param urlTemplate  a URL template; the resulting URL will be encoded
+	 * @param urlVariables zero or more URL variables
+	 */
+	public static DefaultHttpRequestBuilder options(String urlTemplate, Object... urlVariables) {
+		return new DefaultHttpRequestBuilder(HttpMethod.OPTIONS, urlTemplate, urlVariables);
+	}
+
+	/**
+	 * Create a {@link DefaultHttpRequestBuilder} for a HEAD request.
+	 *
+	 * @param urlTemplate  a URL template; the resulting URL will be encoded
+	 * @param urlVariables zero or more URL variables
+	 */
+	public static DefaultHttpRequestBuilder head(String urlTemplate, Object... urlVariables) {
+		return new DefaultHttpRequestBuilder(HttpMethod.HEAD, urlTemplate, urlVariables);
+	}
+
+	/**
+	 * Create a {@link DefaultHttpRequestBuilder} for a request with the given HTTP method.
+	 *
+	 * @param httpMethod   the HTTP method
+	 * @param urlTemplate  a URL template; the resulting URL will be encoded
+	 * @param urlVariables zero or more URL variables
+	 */
+	public static DefaultHttpRequestBuilder request(HttpMethod httpMethod, String urlTemplate, Object... urlVariables) {
+		return new DefaultHttpRequestBuilder(httpMethod, urlTemplate, urlVariables);
+	}
+
+}