Fix incorrect handling of '+' character in query parameter encoding

Signed-off-by: raccoonback <kosb15@naver.com>

Author: raccoonback

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/common/MvcUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2023 the original author or authors.
+ * Copyright 2013-2025 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.
@@ -21,6 +21,7 @@
 import java.io.InputStream;
 import java.io.UncheckedIOException;
 import java.net.URI;
+import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
@@ -40,11 +41,14 @@
 import org.springframework.http.converter.HttpMessageConverter;
 import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
+import org.springframework.util.LinkedMultiValueMap;
+import org.springframework.util.MultiValueMap;
 import org.springframework.util.StreamUtils;
 import org.springframework.web.context.WebApplicationContext;
 import org.springframework.web.servlet.function.ServerRequest;
 import org.springframework.web.servlet.support.RequestContextUtils;
 import org.springframework.web.util.UriComponentsBuilder;
+import org.springframework.web.util.UriUtils;
 
 import static org.springframework.web.servlet.function.RouterFunctions.URI_TEMPLATE_VARIABLES_ATTRIBUTE;
 
@@ -263,6 +267,17 @@ public static void addOriginalRequestUrl(ServerRequest request, URI url) {
 		urls.add(url);
 	}
 
+	public static MultiValueMap<String, String> encodeQueryParams(MultiValueMap<String, String> params) {
+		MultiValueMap<String, String> encodedQueryParams = new LinkedMultiValueMap<>(params.size());
+		for (Map.Entry<String, List<String>> entry : params.entrySet()) {
+			for (String value : entry.getValue()) {
+				encodedQueryParams.add(UriUtils.encode(entry.getKey(), StandardCharsets.UTF_8),
+						UriUtils.encode(value, StandardCharsets.UTF_8));
+			}
+		}
+		return CollectionUtils.unmodifiableMultiValueMap(encodedQueryParams);
+	}
+
 	private record ByteArrayInputMessage(ServerRequest request, ByteArrayInputStream body) implements HttpInputMessage {
 
 		@Override

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/handler/ProxyExchangeHandlerFunction.java

@@ -36,7 +36,6 @@
 import org.springframework.web.servlet.function.ServerRequest;
 import org.springframework.web.servlet.function.ServerResponse;
 import org.springframework.web.util.UriComponentsBuilder;
-import org.springframework.web.util.UriUtils;
 
 /**
  * @author raccoonback
@@ -139,7 +138,7 @@ private static MultiValueMap<String, String> ensureEncodedQueryParameters(Server
 		boolean encoded = containsEncodedQuery(serverRequest.uri(), serverRequest.params());
 		MultiValueMap<String, String> params = serverRequest.params();
 		if (!encoded) {
-			params = UriUtils.encodeQueryParams(serverRequest.params());
+			params = MvcUtils.encodeQueryParams(serverRequest.params());
 		}
 		return params;
 	}

spring-cloud-gateway-server-mvc/src/test/java/org/springframework/cloud/gateway/server/mvc/handler/ProxyExchangeHandlerFunctionTest.java

@@ -103,7 +103,7 @@ public Stream<ResponseHttpHeadersFilter> orderedStream() {
 		function.onApplicationEvent(null);
 
 		MockHttpServletRequest servletRequest = MockMvcRequestBuilders
-			.get("http://localhost/é?foo=value1 value2&bar=value3=")
+			.get("http://localhost/é?foo=value1 value2&bar=value3=&qux=value4+")
 			.buildRequest(null);
 		servletRequest.setAttribute(MvcUtils.GATEWAY_REQUEST_URL_ATTR, URI.create("http://localhost:8080"));
 		ServerRequest request = ServerRequest.create(servletRequest, Collections.emptyList());
@@ -112,10 +112,11 @@ public Stream<ResponseHttpHeadersFilter> orderedStream() {
 
 		URI uri = proxyExchange.getRequest().getUri();
 
-		assertThat(uri).hasToString("http://localhost:8080/%C3%A9?foo=value1%20value2&bar=value3%3D")
+		assertThat(uri).hasToString("http://localhost:8080/%C3%A9?foo=value1%20value2&bar=value3%3D&qux=value4%2B")
 			.hasPath("/é")
 			.hasParameter("foo", "value1 value2")
-			.hasParameter("bar", "value3=");
+			.hasParameter("bar", "value3=")
+			.hasParameter("qux", "value4+");
 	}
 
 	private class TestProxyExchange extends AbstractProxyExchange {