Respect MediaType charset in Jackson converters

Before this commit, AbstractJackson2HttpMessageConverter and subclasses
did not check media type encoding in the canRead and canWrite
methods. As a result, the converter reported that it can write
(for instance) "application/json;charset=ISO-8859-1", but in practice
wrote the default charset (UTF-8).

This commit fixes that bug.

See: spring-projectsgh-25076

spring-web/src/main/java/org/springframework/http/converter/json/AbstractJackson2HttpMessageConverter.java

@@ -22,7 +22,11 @@
 import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
 import java.util.Collections;
+import java.util.EnumSet;
+import java.util.Map;
 import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.Function;
+import java.util.stream.Collectors;
 
 import com.fasterxml.jackson.core.JsonEncoding;
 import com.fasterxml.jackson.core.JsonGenerator;
@@ -69,6 +73,8 @@
  */
 public abstract class AbstractJackson2HttpMessageConverter extends AbstractGenericHttpMessageConverter<Object> {
 
+	private static final Map<String, JsonEncoding> ENCODINGS = jsonEncodings();
+
 	/**
 	 * The default charset used by the converter.
 	 */
@@ -167,6 +173,14 @@ public boolean canRead(Type type, @Nullable Class<?> contextClass, @Nullable Med
 		return false;
 	}
 
+	@Override
+	protected boolean canRead(@Nullable MediaType mediaType) {
+		if (!super.canRead(mediaType)) {
+			return false;
+		}
+		return checkEncoding(mediaType);
+	}
+
 	@Override
 	public boolean canWrite(Class<?> clazz, @Nullable MediaType mediaType) {
 		if (!canWrite(mediaType)) {
@@ -180,6 +194,14 @@ public boolean canWrite(Class<?> clazz, @Nullable MediaType mediaType) {
 		return false;
 	}
 
+	@Override
+	protected boolean canWrite(@Nullable MediaType mediaType) {
+		if (!super.canWrite(mediaType)) {
+			return false;
+		}
+		return checkEncoding(mediaType);
+	}
+
 	/**
 	 * Determine whether to log the given exception coming from a
 	 * {@link ObjectMapper#canDeserialize} / {@link ObjectMapper#canSerialize} check.
@@ -211,6 +233,14 @@ else if (logger.isDebugEnabled()) {
 		}
 	}
 
+	private boolean checkEncoding(@Nullable MediaType mediaType) {
+		if (mediaType != null && mediaType.getCharset() != null) {
+			Charset charset = mediaType.getCharset();
+			return ENCODINGS.containsKey(charset.name());
+		}
+		return true;
+	}
+
 	@Override
 	protected Object readInternal(Class<?> clazz, HttpInputMessage inputMessage)
 			throws IOException, HttpMessageNotReadableException {
@@ -333,10 +363,9 @@ protected JavaType getJavaType(Type type, @Nullable Class<?> contextClass) {
 	protected JsonEncoding getJsonEncoding(@Nullable MediaType contentType) {
 		if (contentType != null && contentType.getCharset() != null) {
 			Charset charset = contentType.getCharset();
-			for (JsonEncoding encoding : JsonEncoding.values()) {
-				if (charset.name().equals(encoding.getJavaName())) {
-					return encoding;
-				}
+			JsonEncoding encoding = ENCODINGS.get(charset.name());
+			if (encoding != null) {
+				return encoding;
 			}
 		}
 		return JsonEncoding.UTF8;
@@ -359,4 +388,9 @@ protected Long getContentLength(Object object, @Nullable MediaType contentType)
 		return super.getContentLength(object, contentType);
 	}
 
+	private static Map<String, JsonEncoding> jsonEncodings() {
+		return EnumSet.allOf(JsonEncoding.class).stream()
+				.collect(Collectors.toMap(JsonEncoding::getJavaName, Function.identity()));
+	}
+
 }

spring-web/src/test/java/org/springframework/http/converter/json/MappingJackson2HttpMessageConverterTests.java

@@ -63,12 +63,16 @@ public class MappingJackson2HttpMessageConverterTests {
 	public void canRead() {
 		assertTrue(converter.canRead(MyBean.class, new MediaType("application", "json")));
 		assertTrue(converter.canRead(Map.class, new MediaType("application", "json")));
+		assertTrue(converter.canRead(MyBean.class, new MediaType("application", "json", StandardCharsets.UTF_8)));
+		assertFalse(converter.canRead(MyBean.class, new MediaType("application", "json", StandardCharsets.ISO_8859_1)));
 	}
 
 	@Test
 	public void canWrite() {
 		assertTrue(converter.canWrite(MyBean.class, new MediaType("application", "json")));
 		assertTrue(converter.canWrite(Map.class, new MediaType("application", "json")));
+		assertTrue(converter.canWrite(MyBean.class, new MediaType("application", "json", StandardCharsets.UTF_8)));
+		assertFalse(converter.canWrite(MyBean.class, new MediaType("application", "json", StandardCharsets.ISO_8859_1)));
 	}
 
 	@Test  // SPR-7905

spring-web/src/test/java/org/springframework/http/converter/smile/MappingJackson2SmileHttpMessageConverterTests.java

@@ -49,13 +49,17 @@ public void canRead() {
 		assertTrue(converter.canRead(MyBean.class, new MediaType("application", "x-jackson-smile")));
 		assertFalse(converter.canRead(MyBean.class, new MediaType("application", "json")));
 		assertFalse(converter.canRead(MyBean.class, new MediaType("application", "xml")));
+		assertTrue(converter.canRead(MyBean.class, new MediaType("application", "x-jackson-smile", StandardCharsets.UTF_8)));
+		assertFalse(converter.canRead(MyBean.class, new MediaType("application", "x-jackson-smile", StandardCharsets.ISO_8859_1)));
 	}
 
 	@Test
 	public void canWrite() {
 		assertTrue(converter.canWrite(MyBean.class, new MediaType("application", "x-jackson-smile")));
 		assertFalse(converter.canWrite(MyBean.class, new MediaType("application", "json")));
 		assertFalse(converter.canWrite(MyBean.class, new MediaType("application", "xml")));
+		assertTrue(converter.canWrite(MyBean.class, new MediaType("application", "x-jackson-smile", StandardCharsets.UTF_8)));
+		assertFalse(converter.canWrite(MyBean.class, new MediaType("application", "x-jackson-smile", StandardCharsets.ISO_8859_1)));
 	}
 
 	@Test

spring-web/src/test/java/org/springframework/http/converter/xml/MappingJackson2XmlHttpMessageConverterTests.java

@@ -54,13 +54,17 @@ public void canRead() {
 		assertTrue(converter.canRead(MyBean.class, new MediaType("application", "xml")));
 		assertTrue(converter.canRead(MyBean.class, new MediaType("text", "xml")));
 		assertTrue(converter.canRead(MyBean.class, new MediaType("application", "soap+xml")));
+		assertTrue(converter.canRead(MyBean.class, new MediaType("text", "xml", StandardCharsets.UTF_8)));
+		assertFalse(converter.canRead(MyBean.class, new MediaType("text", "xml", StandardCharsets.ISO_8859_1)));
 	}
 
 	@Test
 	public void canWrite() {
 		assertTrue(converter.canWrite(MyBean.class, new MediaType("application", "xml")));
 		assertTrue(converter.canWrite(MyBean.class, new MediaType("text", "xml")));
 		assertTrue(converter.canWrite(MyBean.class, new MediaType("application", "soap+xml")));
+		assertTrue(converter.canWrite(MyBean.class, new MediaType("text", "xml", StandardCharsets.UTF_8)));
+		assertFalse(converter.canWrite(MyBean.class, new MediaType("text", "xml", StandardCharsets.ISO_8859_1)));
 	}
 
 	@Test