Add json, html, and xml RequestPredicates

Added RequestPredicate for JSON, HTML, and XML requests. All three tests
for their respective mime type in the Accept header, as well as checking
for a file extension.

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

@@ -36,6 +36,7 @@ import org.springframework.util.PathMatcher;
 import org.springframework.web.reactive.function.BodyExtractor;
 import org.springframework.web.server.WebSession;
 import org.springframework.web.util.ParsingPathMatcher;
+import org.springframework.web.util.UriUtils;
 
 /**
  * Implementations of {@link RequestPredicate} that implement various useful request matching operations, such as
@@ -85,7 +86,10 @@ public abstract class RequestPredicates {
 	 * @return a predicate that tests against the given path pattern
 	 */
 	public static RequestPredicate path(String pattern, PathMatcher pathMatcher) {
-		return new PathPredicate(pattern, pathMatcher);
+		Assert.notNull(pattern, "'pattern' must not be null");
+		Assert.notNull(pathMatcher, "'pathMatcher' must not be null");
+
+		return new PathMatchingPredicate(pattern, pathMatcher);
 	}
 
 	/**
@@ -95,7 +99,7 @@ public abstract class RequestPredicates {
 	 * @return a predicate that tests against the given header predicate
 	 */
 	public static RequestPredicate headers(Predicate<ServerRequest.Headers> headersPredicate) {
-		return new HeaderPredicates(headersPredicate);
+		return new HeadersPredicate(headersPredicate);
 	}
 
 	/**
@@ -221,6 +225,90 @@ public abstract class RequestPredicates {
 		return method(HttpMethod.OPTIONS).and(path(pattern));
 	}
 
+	/**
+	 * Return a {@code RequestPredicate} that matches if the request's path has the given extension.
+	 * @param extension the path extension to match against
+	 * @return a predicate that matches if the request's path has the given file extension
+	 */
+	public static RequestPredicate pathExtension(String extension) {
+		Assert.notNull(extension, "'extension' must not be null");
+		return pathExtension(extension::equalsIgnoreCase);
+	}
+
+	/**
+	 * Return a {@code RequestPredicate} that matches if the request's path matches the given
+	 * predicate.
+	 * @param extensionPredicate the predicate to test against the request path extension
+	 * @return a predicate that matches if the given predicate matches against the request's path
+	 * file extension
+	 */
+	public static RequestPredicate pathExtension(Predicate<String> extensionPredicate) {
+		Assert.notNull(extensionPredicate, "'extensionPredicate' must not be null");
+		return request -> {
+			String pathExtension = UriUtils.extractFileExtension(request.path());
+			return extensionPredicate.test(pathExtension);
+		};
+	}
+
+	/**
+	 * Return a {@code RequestPredicate} that tests the request's query parameter of the given name
+	 * against the given predicate.
+	 * @param name the name of the query parameter to test against
+	 * @param predicate predicate to test against the query parameter value
+	 * @return a predicate that matches the given predicate against the query parameter of the given
+	 * name
+	 * @see ServerRequest#queryParam(String)
+	 */
+	public static RequestPredicate queryParam(String name, Predicate<String> predicate) {
+		return request -> {
+			Optional<String> s = request.queryParam(name);
+			return s.filter(predicate).isPresent();
+		};
+	}
+
+	/**
+	 * Return a {@code RequestPredicate} that matches JSON requests. The returned predicate
+	 * matches if the request has {@code application/json} in the {@code Accept} header, or if the
+	 * request path has a {@code .json} file extension.
+	 *
+	 * @return a predicate that matches JSON
+	 * @see #accept(MediaType...)
+	 * @see #pathExtension(String)
+	 */
+	public static RequestPredicate json() {
+		return accept(MediaType.APPLICATION_JSON)
+				.or(pathExtension("json"));
+	}
+
+	/**
+	 * Return a {@code RequestPredicate} that matches HTML requests. The returned predicate
+	 * matches if the request has {@code text/html} in the {@code Accept} header, or if the request
+	 * path has a {@code .html} file extension.
+	 *
+	 * @return a predicate that matches HTML requests
+	 * @see #accept(MediaType...)
+	 * @see #pathExtension(String)
+	 */
+	public static RequestPredicate html() {
+		return accept(MediaType.TEXT_HTML)
+				.or(pathExtension("html"));
+	}
+
+	/**
+	 * Return a {@code RequestPredicate} that matches XML requests. The returned predicate
+	 * matches if the request has {@code text/xml} or {@code application/xml} in the {@code Accept}
+	 * header, or if the request path has a {@code .xml} file extension.
+	 *
+	 * @return a predicate that matches XML requests
+	 * @see #accept(MediaType...)
+	 * @see #pathExtension(String)
+	 */
+	public static RequestPredicate xml() {
+		return accept(MediaType.TEXT_XML)
+				.or(accept(MediaType.APPLICATION_XML))
+				.or(pathExtension("xml"));
+	}
+
 	private static class HttpMethodPredicate implements RequestPredicate {
 
 		private final HttpMethod httpMethod;
@@ -236,13 +324,13 @@ public abstract class RequestPredicates {
 		}
 	}
 
-	private static class PathPredicate implements RequestPredicate {
+	private static class PathMatchingPredicate implements RequestPredicate {
 
 		private final String pattern;
 
 		private final PathMatcher pathMatcher;
 
-		public PathPredicate(String pattern, PathMatcher pathMatcher) {
+		public PathMatchingPredicate(String pattern, PathMatcher pathMatcher) {
 			Assert.notNull(pattern, "'pattern' must not be null");
 			Assert.notNull(pathMatcher, "'pathMatcher' must not be null");
 			this.pattern = pattern;
@@ -273,11 +361,11 @@ public abstract class RequestPredicates {
 		}
 	}
 
-	private static class HeaderPredicates implements RequestPredicate {
+	private static class HeadersPredicate implements RequestPredicate {
 
 		private final Predicate<ServerRequest.Headers> headersPredicate;
 
-		public HeaderPredicates(Predicate<ServerRequest.Headers> headersPredicate) {
+		public HeadersPredicate(Predicate<ServerRequest.Headers> headersPredicate) {
 			Assert.notNull(headersPredicate, "'headersPredicate' must not be null");
 			this.headersPredicate = headersPredicate;
 		}

spring-webflux/src/test/java/org/springframework/web/reactive/function/server/RequestPredicatesTests.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.
@@ -130,4 +130,96 @@ public class RequestPredicatesTests {
 		assertFalse(predicate.test(request));
 	}
 
+	@Test
+	public void pathExtension() throws Exception {
+		URI uri = URI.create("http://localhost/file.txt");
+		RequestPredicate predicate = RequestPredicates.pathExtension("txt");
+		MockServerRequest request = MockServerRequest.builder().uri(uri).build();
+		assertTrue(predicate.test(request));
+
+		predicate = RequestPredicates.pathExtension("bar");
+		assertFalse(predicate.test(request));
+
+		uri = URI.create("http://localhost/file.foo");
+		request = MockServerRequest.builder().uri(uri).build();
+		assertFalse(predicate.test(request));
+
+	}
+
+	@Test
+	public void queryParam() throws Exception {
+		MockServerRequest request = MockServerRequest.builder().queryParam("foo", "bar").build();
+		RequestPredicate predicate = RequestPredicates.queryParam("foo", s -> s.equals("bar"));
+		assertTrue(predicate.test(request));
+
+		predicate = RequestPredicates.queryParam("foo", s -> s.equals("baz"));
+		assertFalse(predicate.test(request));
+	}
+
+	@Test
+	public void json() throws Exception {
+		RequestPredicate predicate = RequestPredicates.json();
+		MockServerRequest request = MockServerRequest.builder().header("Accept", MediaType.APPLICATION_JSON.toString()).build();
+		assertTrue(predicate.test(request));
+
+		request = MockServerRequest.builder().header("Accept", MediaType.TEXT_HTML.toString()).build();
+		assertFalse(predicate.test(request));
+
+		URI uri = URI.create("http://localhost/file.json");
+		request = MockServerRequest.builder().uri(uri).build();
+		assertTrue(predicate.test(request));
+
+		uri = URI.create("http://localhost/file.html");
+		request = MockServerRequest.builder().uri(uri).build();
+		assertFalse(predicate.test(request));
+
+		request = MockServerRequest.builder().build();
+		assertFalse(predicate.test(request));
+	}
+
+	@Test
+	public void html() throws Exception {
+		RequestPredicate predicate = RequestPredicates.html();
+		MockServerRequest request = MockServerRequest.builder().header("Accept", MediaType.TEXT_HTML.toString()).build();
+		assertTrue(predicate.test(request));
+
+		request = MockServerRequest.builder().header("Accept", MediaType.APPLICATION_JSON.toString()).build();
+		assertFalse(predicate.test(request));
+
+		URI uri = URI.create("http://localhost/file.html");
+		request = MockServerRequest.builder().uri(uri).build();
+		assertTrue(predicate.test(request));
+
+		uri = URI.create("http://localhost/file.json");
+		request = MockServerRequest.builder().uri(uri).build();
+		assertFalse(predicate.test(request));
+
+		request = MockServerRequest.builder().build();
+		assertFalse(predicate.test(request));
+	}
+
+	@Test
+	public void xml() throws Exception {
+		RequestPredicate predicate = RequestPredicates.xml();
+		MockServerRequest request = MockServerRequest.builder().header("Accept", MediaType.TEXT_XML.toString()).build();
+		assertTrue(predicate.test(request));
+
+		request = MockServerRequest.builder().header("Accept", MediaType.APPLICATION_XML.toString()).build();
+		assertTrue(predicate.test(request));
+
+		request = MockServerRequest.builder().header("Accept", MediaType.TEXT_HTML.toString()).build();
+		assertFalse(predicate.test(request));
+
+		URI uri = URI.create("http://localhost/file.xml");
+		request = MockServerRequest.builder().uri(uri).build();
+		assertTrue(predicate.test(request));
+
+		uri = URI.create("http://localhost/file.json");
+		request = MockServerRequest.builder().uri(uri).build();
+		assertFalse(predicate.test(request));
+
+		request = MockServerRequest.builder().build();
+		assertFalse(predicate.test(request));
+	}
+
 }