Avoid setCharacterEncoding(Charset) call with null value

jhoeller · jhoeller · commit 727ccd04efe7 · 2026-02-17T18:56:59.000+01:00
Includes consistent content length check for functional response. See gh-36343
diff --git a/spring-web/src/main/java/org/springframework/http/server/ServletServerHttpResponse.java b/spring-web/src/main/java/org/springframework/http/server/ServletServerHttpResponse.java
@@ -18,6 +18,7 @@
 
 import java.io.IOException;
 import java.io.OutputStream;
+import java.nio.charset.Charset;
 
 import jakarta.servlet.http.HttpServletResponse;
 import org.jspecify.annotations.Nullable;
@@ -116,15 +117,18 @@ private void writeHeaders() {
 					// Lazy parsing into MediaType
 					MediaType contentType = this.headers.getContentType();
 					if (contentType != null) {
-						this.servletResponse.setCharacterEncoding(contentType.getCharset());
+						Charset charset = contentType.getCharset();
+						if (charset != null) {
+							this.servletResponse.setCharacterEncoding(charset);
+						}
 					}
 				}
 				catch (Exception ex) {
 					// Leave character encoding unspecified
 				}
 			}
+			this.headersWritten = true;
 		}
-		this.headersWritten = true;
 	}
 
 }
diff --git a/spring-web/src/main/java/org/springframework/http/server/reactive/ServletServerHttpResponse.java b/spring-web/src/main/java/org/springframework/http/server/reactive/ServletServerHttpResponse.java
@@ -18,6 +18,7 @@
 
 import java.io.IOException;
 import java.nio.ByteBuffer;
+import java.nio.charset.Charset;
 
 import jakarta.servlet.AsyncContext;
 import jakarta.servlet.AsyncEvent;
@@ -122,25 +123,26 @@ protected void applyHeaders() {
 
 	protected void adaptHeaders(boolean removeAdaptedHeaders) {
 		HttpHeaders headers = getHeaders();
-		// HttpServletResponse exposes some headers as properties: we should include those if not already present
 
+		// HttpServletResponse exposes some headers as properties: we should include those if not already present
 		if (this.response.getContentType() == null && headers.containsHeader(HttpHeaders.CONTENT_TYPE)) {
 			this.response.setContentType(headers.getFirst(HttpHeaders.CONTENT_TYPE));
 		}
-
 		if (this.response.getCharacterEncoding() == null && headers.containsHeader(HttpHeaders.CONTENT_TYPE)) {
 			try {
 				// Lazy parsing into MediaType
 				MediaType contentType = headers.getContentType();
 				if (contentType != null) {
-					this.response.setCharacterEncoding(contentType.getCharset());
+					Charset charset = contentType.getCharset();
+					if (charset != null) {
+						this.response.setCharacterEncoding(charset);
+					}
 				}
 			}
 			catch (Exception ex) {
 				// Leave character encoding unspecified
 			}
 		}
-
 		long contentLength = headers.getContentLength();
 		if (contentLength != -1) {
 			this.response.setContentLengthLong(contentLength);
diff --git a/spring-webmvc/src/main/java/org/springframework/web/servlet/function/AbstractServerResponse.java b/spring-webmvc/src/main/java/org/springframework/web/servlet/function/AbstractServerResponse.java
@@ -17,6 +17,7 @@
 package org.springframework.web.servlet.function;
 
 import java.io.IOException;
+import java.nio.charset.Charset;
 import java.util.Collection;
 import java.util.Set;
 
@@ -61,6 +62,7 @@ protected AbstractServerResponse(
 		this.cookies = CollectionUtils.unmodifiableMultiValueMap(new LinkedMultiValueMap<>(cookies));
 	}
 
+
 	@Override
 	public final HttpStatusCode statusCode() {
 		return this.statusCode;
@@ -121,13 +123,20 @@ private void writeHeaders(HttpServletResponse servletResponse) {
 				// Lazy parsing into MediaType
 				MediaType contentType = this.headers.getContentType();
 				if (contentType != null) {
-					servletResponse.setCharacterEncoding(contentType.getCharset());
+					Charset charset = contentType.getCharset();
+					if (charset != null) {
+						servletResponse.setCharacterEncoding(charset);
+					}
 				}
 			}
 			catch (Exception ex) {
 				// Leave character encoding unspecified
 			}
 		}
+		long contentLength = this.headers.getContentLength();
+		if (contentLength != -1) {
+			servletResponse.setContentLengthLong(contentLength);
+		}
 	}
 
 	private void writeCookies(HttpServletResponse servletResponse) {

Original file line number	Diff line number	Diff line change
`@@ -18,6 +18,7 @@`
`18`	`18`
`19`	`19`	`import java.io.IOException;`
`20`	`20`	`import java.io.OutputStream;`
	`21`	`+import java.nio.charset.Charset;`
`21`	`22`
`22`	`23`	`import jakarta.servlet.http.HttpServletResponse;`
`23`	`24`	`import org.jspecify.annotations.Nullable;`
`@@ -116,15 +117,18 @@ private void writeHeaders() {`
`116`	`117`	`// Lazy parsing into MediaType`
`117`	`118`	`MediaType contentType = this.headers.getContentType();`
`118`	`119`	`if (contentType != null) {`
`119`		`- this.servletResponse.setCharacterEncoding(contentType.getCharset());`
	`120`	`+ Charset charset = contentType.getCharset();`
	`121`	`+ if (charset != null) {`
	`122`	`+ this.servletResponse.setCharacterEncoding(charset);`
	`123`	`+ }`
`120`	`124`	`}`
`121`	`125`	`}`
`122`	`126`	`catch (Exception ex) {`
`123`	`127`	`// Leave character encoding unspecified`
`124`	`128`	`}`
`125`	`129`	`}`
	`130`	`+ this.headersWritten = true;`
`126`	`131`	`}`
`127`		`- this.headersWritten = true;`
`128`	`132`	`}`
`129`	`133`
`130`	`134`	`}`
Original file line number	Diff line number	Diff line change
`@@ -17,6 +17,7 @@`
`17`	`17`	`package org.springframework.web.servlet.function;`
`18`	`18`
`19`	`19`	`import java.io.IOException;`
	`20`	`+import java.nio.charset.Charset;`
`20`	`21`	`import java.util.Collection;`
`21`	`22`	`import java.util.Set;`
`22`	`23`
`@@ -61,6 +62,7 @@ protected AbstractServerResponse(`
`61`	`62`	`this.cookies = CollectionUtils.unmodifiableMultiValueMap(new LinkedMultiValueMap<>(cookies));`
`62`	`63`	`}`
`63`	`64`
	`65`	`+`
`64`	`66`	`@Override`
`65`	`67`	`public final HttpStatusCode statusCode() {`
`66`	`68`	`return this.statusCode;`
`@@ -121,13 +123,20 @@ private void writeHeaders(HttpServletResponse servletResponse) {`
`121`	`123`	`// Lazy parsing into MediaType`
`122`	`124`	`MediaType contentType = this.headers.getContentType();`
`123`	`125`	`if (contentType != null) {`
`124`		`- servletResponse.setCharacterEncoding(contentType.getCharset());`
	`126`	`+ Charset charset = contentType.getCharset();`
	`127`	`+ if (charset != null) {`
	`128`	`+ servletResponse.setCharacterEncoding(charset);`
	`129`	`+ }`
`125`	`130`	`}`
`126`	`131`	`}`
`127`	`132`	`catch (Exception ex) {`
`128`	`133`	`// Leave character encoding unspecified`
`129`	`134`	`}`
`130`	`135`	`}`
	`136`	`+ long contentLength = this.headers.getContentLength();`
	`137`	`+ if (contentLength != -1) {`
	`138`	`+ servletResponse.setContentLengthLong(contentLength);`
	`139`	`+ }`
`131`	`140`	`}`
`132`	`141`
`133`	`142`	`private void writeCookies(HttpServletResponse servletResponse) {`