UriComponents support for array query params

Issue: SPR-9712

spring-web/src/main/java/org/springframework/web/util/HierarchicalUriComponents.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * 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.
@@ -336,6 +336,7 @@ final class HierarchicalUriComponents extends UriComponents {
 	private MultiValueMap<String, String> expandQueryParams(UriTemplateVariables variables) {
 		int size = this.queryParams.size();
 		MultiValueMap<String, String> result = new LinkedMultiValueMap<String, String>(size);
+		variables = new QueryUriTemplateVariables(variables);
 		for (Map.Entry<String, List<String>> entry : this.queryParams.entrySet()) {
 			String name = expandUriComponent(entry.getKey(), variables);
 			List<String> values = new ArrayList<String>(entry.getValue().size());
@@ -882,4 +883,22 @@ final class HierarchicalUriComponents extends UriComponents {
 		}
 	};
 
+	private static class QueryUriTemplateVariables implements UriTemplateVariables {
+
+		private final UriTemplateVariables delegate;
+
+		public QueryUriTemplateVariables(UriTemplateVariables delegate) {
+			this.delegate = delegate;
+		}
+
+		@Override
+		public Object getValue(String name) {
+			Object value = this.delegate.getValue(name);
+			if (ObjectUtils.isArray(value)) {
+				value = StringUtils.arrayToCommaDelimitedString(ObjectUtils.toObjectArray(value));
+			}
+			return value;
+		}
+	}
+
 }

spring-web/src/test/java/org/springframework/web/util/UriTemplateTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * 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.
@@ -30,6 +30,7 @@ import static org.junit.Assert.*;
 /**
  * @author Arjen Poutsma
  * @author Juergen Hoeller
+ * @author Rossen Stoyanchev
  */
 public class UriTemplateTests {
 
@@ -47,6 +48,15 @@ public class UriTemplateTests {
 		assertEquals("Invalid expanded template", new URI("http://example.com/hotels/1/bookings/42"), result);
 	}
 
+	// SPR-9712
+
+	@Test @SuppressWarnings("PrimitiveArrayArgumentToVariableArgMethod")
+	public void expandVarArgsWithArrayValue() throws Exception {
+		UriTemplate template = new UriTemplate("/sum?numbers={numbers}");
+		URI result = template.expand(new int[] {1, 2, 3});
+		assertEquals(new URI("/sum?numbers=1,2,3"), result);
+	}
+
 	@Test(expected = IllegalArgumentException.class)
 	public void expandVarArgsNotEnoughVariables() throws Exception {
 		UriTemplate template = new UriTemplate("http://example.com/hotels/{hotel}/bookings/{booking}");