Merge pull request #31781 from rstoyanchev

* pr/31781:
  Write form data without charset parameter

Closes gh-31781

Author: snicoll

spring-web/src/main/java/org/springframework/http/codec/FormHttpMessageWriter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 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.
@@ -60,14 +60,9 @@
 public class FormHttpMessageWriter extends LoggingCodecSupport
 		implements HttpMessageWriter<MultiValueMap<String, String>> {
 
-	/**
-	 * The default charset used by the writer.
-	 */
+	/** The default charset used by the writer. */
 	public static final Charset DEFAULT_CHARSET = StandardCharsets.UTF_8;
 
-	private static final MediaType DEFAULT_FORM_DATA_MEDIA_TYPE =
-			new MediaType(MediaType.APPLICATION_FORM_URLENCODED, DEFAULT_CHARSET);
-
 	private static final List<MediaType> MEDIA_TYPES =
 			Collections.singletonList(MediaType.APPLICATION_FORM_URLENCODED);
 
@@ -126,7 +121,7 @@ public Mono<Void> write(Publisher<? extends MultiValueMap<String, String>> input
 		mediaType = getMediaType(mediaType);
 		message.getHeaders().setContentType(mediaType);
 
-		Charset charset = mediaType.getCharset() != null ? mediaType.getCharset() : getDefaultCharset();
+		Charset charset = (mediaType.getCharset() != null ? mediaType.getCharset() : getDefaultCharset());
 
 		return Mono.from(inputStream).flatMap(form -> {
 			logFormData(form, hints);
@@ -138,16 +133,22 @@ public Mono<Void> write(Publisher<? extends MultiValueMap<String, String>> input
 		});
 	}
 
+	/**
+	 * Return the content type used to write forms, either the given media type
+	 * or otherwise {@code application/x-www-form-urlencoded}.
+	 * @param mediaType the media type passed to {@link #write}, or {@code null}
+	 * @return the content type to use
+	 */
 	protected MediaType getMediaType(@Nullable MediaType mediaType) {
 		if (mediaType == null) {
-			return DEFAULT_FORM_DATA_MEDIA_TYPE;
-		}
-		else if (mediaType.getCharset() == null) {
-			return new MediaType(mediaType, getDefaultCharset());
+			return MediaType.APPLICATION_FORM_URLENCODED;
 		}
-		else {
-			return mediaType;
+		// Some servers don't handle charset parameter and spec is unclear,
+		// Add it only if it is not DEFAULT_CHARSET.
+		if (mediaType.getCharset() == null && this.defaultCharset != DEFAULT_CHARSET) {
+			return new MediaType(mediaType, this.defaultCharset);
 		}
+		return mediaType;
 	}
 
 	private void logFormData(MultiValueMap<String, String> form, Map<String, Object> hints) {

spring-web/src/main/java/org/springframework/http/converter/FormHttpMessageConverter.java

@@ -154,14 +154,9 @@
  */
 public class FormHttpMessageConverter implements HttpMessageConverter<MultiValueMap<String, ?>> {
 
-	/**
-	 * The default charset used by the converter.
-	 */
+	/** The default charset used by the converter. */
 	public static final Charset DEFAULT_CHARSET = StandardCharsets.UTF_8;
 
-	private static final MediaType DEFAULT_FORM_DATA_MEDIA_TYPE =
-			new MediaType(MediaType.APPLICATION_FORM_URLENCODED, DEFAULT_CHARSET);
-
 
 	private List<MediaType> supportedMediaTypes = new ArrayList<>();
 
@@ -387,14 +382,13 @@ private boolean isMultipart(MultiValueMap<String, ?> map, @Nullable MediaType co
 		return false;
 	}
 
-	private void writeForm(MultiValueMap<String, Object> formData, @Nullable MediaType contentType,
+	private void writeForm(MultiValueMap<String, Object> formData, @Nullable MediaType mediaType,
 			HttpOutputMessage outputMessage) throws IOException {
 
-		contentType = getFormContentType(contentType);
-		outputMessage.getHeaders().setContentType(contentType);
+		mediaType = getFormContentType(mediaType);
+		outputMessage.getHeaders().setContentType(mediaType);
 
-		Charset charset = contentType.getCharset();
-		Assert.notNull(charset, "No charset"); // should never occur
+		Charset charset = (mediaType.getCharset() != null ? mediaType.getCharset() : this.charset);
 
 		byte[] bytes = serializeForm(formData, charset).getBytes(charset);
 		outputMessage.getHeaders().setContentLength(bytes.length);
@@ -418,26 +412,22 @@ public boolean repeatable() {
 	}
 
 	/**
-	 * Return the content type used to write forms, given the preferred content type.
-	 * By default, this method returns the given content type, but adds the
-	 * {@linkplain #setCharset(Charset) charset} if it does not have one.
-	 * If {@code contentType} is {@code null},
-	 * {@code application/x-www-form-urlencoded; charset=UTF-8} is returned.
-	 * <p>Subclasses can override this method to change this behavior.
-	 * @param contentType the preferred content type (can be {@code null})
-	 * @return the content type to be used
+	 * Return the content type used to write forms, either the given content type
+	 * or otherwise {@code application/x-www-form-urlencoded}.
+	 * @param contentType the content type passed to {@link #write}, or {@code null}
+	 * @return the content type to use
 	 * @since 5.2.2
 	 */
 	protected MediaType getFormContentType(@Nullable MediaType contentType) {
 		if (contentType == null) {
-			return DEFAULT_FORM_DATA_MEDIA_TYPE;
+			return MediaType.APPLICATION_FORM_URLENCODED;
 		}
-		else if (contentType.getCharset() == null) {
+		// Some servers don't handle charset parameter and spec is unclear,
+		// Add it only if it is not DEFAULT_CHARSET.
+		if (contentType.getCharset() == null && this.charset != DEFAULT_CHARSET) {
 			return new MediaType(contentType, this.charset);
 		}
-		else {
-			return contentType;
-		}
+		return contentType;
 	}
 
 	protected String serializeForm(MultiValueMap<String, Object> formData, Charset charset) {

spring-web/src/test/java/org/springframework/http/codec/FormHttpMessageWriterTests.java

@@ -88,7 +88,7 @@ void writeForm() {
 				.expectComplete()
 				.verify();
 		HttpHeaders headers = response.getHeaders();
-		assertThat(headers.getContentType().toString()).isEqualTo("application/x-www-form-urlencoded;charset=UTF-8");
+		assertThat(headers.getContentType()).isEqualTo(MediaType.APPLICATION_FORM_URLENCODED);
 		assertThat(headers.getContentLength()).isEqualTo(expected.length());
 	}
 

spring-web/src/test/java/org/springframework/http/converter/FormHttpMessageConverterTests.java

@@ -47,6 +47,7 @@
 import org.springframework.web.testfixture.http.MockHttpInputMessage;
 import org.springframework.web.testfixture.http.MockHttpOutputMessage;
 
+import static java.nio.charset.StandardCharsets.UTF_8;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.springframework.http.MediaType.APPLICATION_FORM_URLENCODED;
 import static org.springframework.http.MediaType.APPLICATION_JSON;
@@ -93,7 +94,7 @@ void canWrite() {
 		assertCanWrite(MULTIPART_FORM_DATA);
 		assertCanWrite(MULTIPART_MIXED);
 		assertCanWrite(MULTIPART_RELATED);
-		assertCanWrite(new MediaType("multipart", "form-data", StandardCharsets.UTF_8));
+		assertCanWrite(new MediaType("multipart", "form-data", UTF_8));
 		assertCanWrite(MediaType.ALL);
 		assertCanWrite(null);
 	}
@@ -141,10 +142,10 @@ void writeForm() throws IOException {
 		MockHttpOutputMessage outputMessage = new MockHttpOutputMessage();
 		this.converter.write(body, APPLICATION_FORM_URLENCODED, outputMessage);
 
-		assertThat(outputMessage.getBodyAsString(StandardCharsets.UTF_8))
+		assertThat(outputMessage.getBodyAsString(UTF_8))
 				.as("Invalid result").isEqualTo("name+1=value+1&name+2=value+2%2B1&name+2=value+2%2B2&name+3");
-		assertThat(outputMessage.getHeaders().getContentType().toString())
-				.as("Invalid content-type").isEqualTo("application/x-www-form-urlencoded;charset=UTF-8");
+		assertThat(outputMessage.getHeaders().getContentType())
+				.as("Invalid content-type").isEqualTo(APPLICATION_FORM_URLENCODED);
 		assertThat(outputMessage.getHeaders().getContentLength())
 				.as("Invalid content-length").isEqualTo(outputMessage.getBodyAsBytes().length);
 	}
@@ -178,7 +179,7 @@ public String getFilename() {
 		parts.add("json", entity);
 
 		Map<String, String> parameters = new LinkedHashMap<>(2);
-		parameters.put("charset", StandardCharsets.UTF_8.name());
+		parameters.put("charset", UTF_8.name());
 		parameters.put("foo", "bar");
 
 		MockHttpOutputMessage outputMessage = new MockHttpOutputMessage();
@@ -260,7 +261,7 @@ public String getFilename() {
 		parts.add("xml", entity);
 
 		Map<String, String> parameters = new LinkedHashMap<>(2);
-		parameters.put("charset", StandardCharsets.UTF_8.name());
+		parameters.put("charset", UTF_8.name());
 		parameters.put("foo", "bar");
 
 		MockHttpOutputMessage outputMessage = new MockHttpOutputMessage();
@@ -323,8 +324,8 @@ public void writeMultipartOrder() throws Exception {
 		parts.add("part2", entity);
 
 		MockHttpOutputMessage outputMessage = new MockHttpOutputMessage();
-		this.converter.setMultipartCharset(StandardCharsets.UTF_8);
-		this.converter.write(parts, new MediaType("multipart", "form-data", StandardCharsets.UTF_8), outputMessage);
+		this.converter.setMultipartCharset(UTF_8);
+		this.converter.write(parts, new MediaType("multipart", "form-data", UTF_8), outputMessage);
 
 		final MediaType contentType = outputMessage.getHeaders().getContentType();
 		assertThat(contentType.getParameter("boundary")).as("No boundary found").isNotNull();

spring-web/src/test/java/org/springframework/web/client/AbstractMockWebServerTests.java

@@ -192,7 +192,7 @@ private void assertFilePart(Buffer buffer, String disposition, String boundary,
 	}
 
 	private MockResponse formRequest(RecordedRequest request) {
-		assertThat(request.getHeader(CONTENT_TYPE)).isEqualTo("application/x-www-form-urlencoded;charset=UTF-8");
+		assertThat(request.getHeader(CONTENT_TYPE)).isEqualTo("application/x-www-form-urlencoded");
 		assertThat(request.getBody().readUtf8()).contains("name+1=value+1", "name+2=value+2%2B1", "name+2=value+2%2B2");
 		return new MockResponse().setResponseCode(200);
 	}
@@ -235,7 +235,7 @@ private MockResponse putRequest(RecordedRequest request, String expectedRequestC
 	protected class TestDispatcher extends Dispatcher {
 
 		@Override
-		public MockResponse dispatch(RecordedRequest request) throws InterruptedException {
+		public MockResponse dispatch(RecordedRequest request) {
 			try {
 				byte[] helloWorldBytes = helloWorld.getBytes(StandardCharsets.UTF_8);
 

spring-web/src/test/java/org/springframework/web/client/support/RestClientAdapterTests.java

@@ -188,7 +188,7 @@ void formData(MockWebServer server, Service service) throws Exception {
 		service.postForm(map);
 
 		RecordedRequest request = server.takeRequest();
-		assertThat(request.getHeaders().get("Content-Type")).isEqualTo("application/x-www-form-urlencoded;charset=UTF-8");
+		assertThat(request.getHeaders().get("Content-Type")).isEqualTo("application/x-www-form-urlencoded");
 		assertThat(request.getBody().readUtf8()).isEqualTo("param1=value+1&param2=value+2");
 	}
 

spring-web/src/test/kotlin/org/springframework/web/client/support/KotlinRestTemplateHttpServiceProxyTests.kt

@@ -136,8 +136,7 @@ class KotlinRestTemplateHttpServiceProxyTests {
         testService.postForm(map)
 
         val request = server.takeRequest()
-        assertThat(request.headers["Content-Type"])
-                .isEqualTo("application/x-www-form-urlencoded;charset=UTF-8")
+        assertThat(request.headers["Content-Type"]).isEqualTo("application/x-www-form-urlencoded")
         assertThat(request.body.readUtf8()).isEqualTo("param1=value+1&param2=value+2")
     }
 

spring-webflux/src/test/java/org/springframework/web/reactive/function/client/support/WebClientAdapterTests.java

@@ -145,7 +145,7 @@ void formData() throws Exception {
 		initService().postForm(map);
 
 		RecordedRequest request = this.server.takeRequest();
-		assertThat(request.getHeaders().get("Content-Type")).isEqualTo("application/x-www-form-urlencoded;charset=UTF-8");
+		assertThat(request.getHeaders().get("Content-Type")).isEqualTo("application/x-www-form-urlencoded");
 		assertThat(request.getBody().readUtf8()).isEqualTo("param1=value+1&param2=value+2");
 	}