Optimal charset handling in AbstractHttpMessageConverter

rstoyanchev · rstoyanchev · commit 47a2e7059eb6 · 2026-02-13T12:39:03.000Z
Closes gh-36320
diff --git a/spring-web/src/main/java/org/springframework/http/converter/AbstractHttpMessageConverter.java b/spring-web/src/main/java/org/springframework/http/converter/AbstractHttpMessageConverter.java
@@ -252,13 +252,14 @@ else if (MediaType.APPLICATION_OCTET_STREAM.equals(contentType)) {
 				contentTypeToUse = (mediaType != null ? mediaType : contentTypeToUse);
 			}
 			if (contentTypeToUse != null) {
+				String value = contentTypeToUse.toString();
 				if (contentTypeToUse.getCharset() == null) {
 					Charset defaultCharset = getDefaultCharset();
 					if (defaultCharset != null) {
-						contentTypeToUse = new MediaType(contentTypeToUse, defaultCharset);
+						value += ";charset=" + defaultCharset.name();
 					}
 				}
-				headers.setContentType(contentTypeToUse);
+				headers.set(HttpHeaders.CONTENT_TYPE, value);
 			}
 		}
 		if (headers.getContentLength() < 0 && !headers.containsHeader(HttpHeaders.TRANSFER_ENCODING)) {

Original file line number	Diff line number	Diff line change
`@@ -252,13 +252,14 @@ else if (MediaType.APPLICATION_OCTET_STREAM.equals(contentType)) {`
`252`	`252`	`contentTypeToUse = (mediaType != null ? mediaType : contentTypeToUse);`
`253`	`253`	`}`
`254`	`254`	`if (contentTypeToUse != null) {`
	`255`	`+ String value = contentTypeToUse.toString();`
`255`	`256`	`if (contentTypeToUse.getCharset() == null) {`
`256`	`257`	`Charset defaultCharset = getDefaultCharset();`
`257`	`258`	`if (defaultCharset != null) {`
`258`		`- contentTypeToUse = new MediaType(contentTypeToUse, defaultCharset);`
	`259`	`+ value += ";charset=" + defaultCharset.name();`
`259`	`260`	`}`
`260`	`261`	`}`
`261`		`- headers.setContentType(contentTypeToUse);`
	`262`	`+ headers.set(HttpHeaders.CONTENT_TYPE, value);`
`262`	`263`	`}`
`263`	`264`	`}`
`264`	`265`	`if (headers.getContentLength() < 0 && !headers.containsHeader(HttpHeaders.TRANSFER_ENCODING)) {`