Resolve UriComponentsBuilder argument with contextPath

Closes gh-25822

spring-webflux/src/main/java/org/springframework/web/reactive/result/method/annotation/ServerWebExchangeMethodArgumentResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -111,7 +111,8 @@ public class ServerWebExchangeMethodArgumentResolver extends HandlerMethodArgume
 		}
 		else if (UriBuilder.class == paramType || UriComponentsBuilder.class == paramType) {
 			URI uri = exchange.getRequest().getURI();
-			return UriComponentsBuilder.fromUri(uri).replacePath(null).replaceQuery(null);
+			String contextPath = exchange.getRequest().getPath().contextPath().value();
+			return UriComponentsBuilder.fromUri(uri).replacePath(contextPath).replaceQuery(null);
 		}
 		else {
 			// should never happen...

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/ServerWebExchangeMethodArgumentResolverTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -97,9 +97,23 @@ public class ServerWebExchangeMethodArgumentResolverTests {
 
 		assertThat(value).isNotNull();
 		assertThat(value.getClass()).isEqualTo(UriComponentsBuilder.class);
-		assertThat(((UriComponentsBuilder) value).path("/next").toUriString()).isEqualTo("https://example.org:9999/next");
+		assertThat(((UriComponentsBuilder) value).path("/next").toUriString())
+				.isEqualTo("https://example.org:9999/next");
 	}
 
+	@Test // gh-25822
+	public void resolveUriComponentsBuilderWithContextPath() {
+		ServerWebExchange exchange = MockServerWebExchange.from(
+				MockServerHttpRequest.get("https://example.org:9999/app/path?q=foo").contextPath("/app"));
+
+		MethodParameter param = this.testMethod.arg(UriComponentsBuilder.class);
+		Object value = this.resolver.resolveArgument(param, new BindingContext(), exchange).block();
+
+		assertThat(value).isNotNull();
+		assertThat(value.getClass()).isEqualTo(UriComponentsBuilder.class);
+		assertThat(((UriComponentsBuilder) value).path("/next").toUriString())
+				.isEqualTo("https://example.org:9999/app/next");
+	}
 
 
 	@SuppressWarnings("unused")

src/docs/asciidoc/web/webflux.adoc

@@ -1903,8 +1903,8 @@ and others) and is equivalent to `required=false`.
   See <<webflux-ann-sessionattributes>> for more details.
 
 | `UriComponentsBuilder`
-| For preparing a URL relative to the current request's host, port, scheme, and path.
+| For preparing a URL relative to the current request's host, port, scheme, and
-  See <<webflux-uri-building>>.
+  context path. See <<webflux-uri-building>>.
 
 | `@SessionAttribute`
 | For access to any session attribute -- in contrast to model attributes stored in the session

src/docs/asciidoc/web/webmvc.adoc

@@ -2085,7 +2085,7 @@ and others) and is equivalent to `required=false`.
 
 | `UriComponentsBuilder`
 | For preparing a URL relative to the current request's host, port, scheme, context path, and
-  the literal  part of the servlet mapping. See <<mvc-uri-building>>.
+  the literal part of the servlet mapping. See <<mvc-uri-building>>.
 
 | `@SessionAttribute`
 | For access to any session attribute, in contrast to model attributes stored in the session