Polishing contribution

Closes gh-28401

spring-web/src/main/java/org/springframework/http/codec/json/AbstractJackson2Decoder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2022 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.
@@ -33,6 +33,7 @@ import com.fasterxml.jackson.databind.util.TokenBuffer;
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
+import reactor.util.context.ContextView;
 
 import org.springframework.core.MethodParameter;
 import org.springframework.core.ResolvableType;
@@ -46,7 +47,6 @@ import org.springframework.core.log.LogFormatUtils;
 import org.springframework.http.codec.HttpMessageDecoder;
 import org.springframework.http.server.reactive.ServerHttpRequest;
 import org.springframework.http.server.reactive.ServerHttpResponse;
-import org.springframework.lang.NonNull;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.MimeType;
@@ -139,22 +139,26 @@ public abstract class AbstractJackson2Decoder extends Jackson2CodecSupport imple
 		Flux<TokenBuffer> tokens = Jackson2Tokenizer.tokenize(processed, mapper.getFactory(), mapper,
 				true, forceUseOfBigDecimal, getMaxInMemorySize());
 
-		ObjectReader objectReader = getObjectReader(mapper, elementType, hints);
-
-		return customizeReaderFromStream(objectReader, mimeType, elementType, hints)
-				.flatMapMany(reader -> tokens.handle((tokenBuffer, sink) -> {
-						try {
-							Object value = reader.readValue(tokenBuffer.asParser(mapper));
-							logValue(value, hints);
-							if (value != null) {
-								sink.next(value);
-							}
-						}
-						catch (IOException ex) {
-							sink.error(processException(ex));
-						}
-					})
-				);
+		return Flux.deferContextual(contextView -> {
+
+			Map<String, Object> hintsToUse = contextView.isEmpty() ? hints :
+					Hints.merge(hints, ContextView.class.getName(), contextView);
+
+			ObjectReader reader = createObjectReader(mapper, elementType, hintsToUse);
+
+			return tokens.handle((tokenBuffer, sink) -> {
+				try {
+					Object value = reader.readValue(tokenBuffer.asParser(mapper));
+					logValue(value, hints);
+					if (value != null) {
+						sink.next(value);
+					}
+				}
+				catch (IOException ex) {
+					sink.error(processException(ex));
+				}
+			});
+		});
 	}
 
 	/**
@@ -169,7 +173,7 @@ public abstract class AbstractJackson2Decoder extends Jackson2CodecSupport imple
 	 * @since 5.1.14
 	 */
 	protected Flux<DataBuffer> processInput(Publisher<DataBuffer> input, ResolvableType elementType,
-				@Nullable MimeType mimeType, @Nullable Map<String, Object> hints) {
+			@Nullable MimeType mimeType, @Nullable Map<String, Object> hints) {
 
 		return Flux.from(input);
 	}
@@ -177,37 +181,28 @@ public abstract class AbstractJackson2Decoder extends Jackson2CodecSupport imple
 	@Override
 	public Mono<Object> decodeToMono(Publisher<DataBuffer> input, ResolvableType elementType,
 			@Nullable MimeType mimeType, @Nullable Map<String, Object> hints) {
-		return DataBufferUtils.join(input, this.maxInMemorySize)
-				.flatMap(dataBuffer -> {
-							try {
-								ObjectReader objectReader = getObjectReader(elementType, mimeType, hints);
-								return customizeReaderFromStream(objectReader, mimeType, elementType, hints)
-										.flatMap(reader -> {
-											try {
-												return Mono.justOrEmpty(decode(dataBuffer, reader, hints));
-											}
-											catch (DecodingException ex) {
-												return Mono.error(ex);
-											}
-										});
-							}
-							catch (IllegalStateException ex) {
-								return Mono.error(ex);
-							}
-						});
+
+		return Mono.deferContextual(contextView -> {
+
+			Map<String, Object> hintsToUse = contextView.isEmpty() ? hints :
+					Hints.merge(hints, ContextView.class.getName(), contextView);
+
+			return DataBufferUtils.join(input, this.maxInMemorySize).flatMap(dataBuffer ->
+					Mono.justOrEmpty(decode(dataBuffer, elementType, mimeType, hintsToUse)));
+		});
 	}
 
 	@Override
 	public Object decode(DataBuffer dataBuffer, ResolvableType targetType,
 			@Nullable MimeType mimeType, @Nullable Map<String, Object> hints) throws DecodingException {
-		ObjectReader reader = getObjectReader(targetType, mimeType, hints);
-		reader = customizeReader(reader, mimeType, targetType, hints);
-		return decode(dataBuffer, reader, hints);
-	}
 
-	private Object decode(@NonNull DataBuffer dataBuffer, @NonNull ObjectReader objectReader,
-			@Nullable Map<String, Object> hints) throws DecodingException {
+		ObjectMapper mapper = selectObjectMapper(targetType, mimeType);
+		if (mapper == null) {
+			throw new IllegalStateException("No ObjectMapper for " + targetType);
+		}
+
 		try {
+			ObjectReader objectReader = createObjectReader(mapper, targetType, hints);
 			Object value = objectReader.readValue(dataBuffer.asInputStream());
 			logValue(value, hints);
 			return value;
@@ -220,16 +215,7 @@ public abstract class AbstractJackson2Decoder extends Jackson2CodecSupport imple
 		}
 	}
 
-	private ObjectReader getObjectReader(ResolvableType targetType, @Nullable MimeType mimeType,
-			@Nullable Map<String, Object> hints) {
-		ObjectMapper mapper = selectObjectMapper(targetType, mimeType);
-		if (mapper == null) {
-			throw new IllegalStateException("No ObjectMapper for " + targetType);
-		}
-		return getObjectReader(mapper, targetType, hints);
-	}
-
-	private ObjectReader getObjectReader(
+	private ObjectReader createObjectReader(
 			ObjectMapper mapper, ResolvableType elementType, @Nullable Map<String, Object> hints) {
 
 		Assert.notNull(elementType, "'elementType' must not be null");
@@ -239,34 +225,28 @@ public abstract class AbstractJackson2Decoder extends Jackson2CodecSupport imple
 		}
 		JavaType javaType = getJavaType(elementType.getType(), contextClass);
 		Class<?> jsonView = (hints != null ? (Class<?>) hints.get(Jackson2CodecSupport.JSON_VIEW_HINT) : null);
-		return jsonView != null ?
+
+		ObjectReader objectReader = (jsonView != null ?
 				mapper.readerWithView(jsonView).forType(javaType) :
-				mapper.readerFor(javaType);
-	}
+				mapper.readerFor(javaType));
 
-	/**
-	 * Provides the ability for subclasses to customize the {@link ObjectReader} for deserialization from a stream.
-	 * @param reader the {@link ObjectReader} available for customization
-	 * @param mimeType the MIME type associated with the input stream
-	 * @param elementType the expected type of elements in the output stream
-	 * @param hints additional information about how to do encode
-	 * @return the customized {@link ObjectReader}
-	 */
-	protected Mono<ObjectReader> customizeReaderFromStream(@NonNull ObjectReader reader, @Nullable MimeType mimeType,
-			ResolvableType elementType, @Nullable Map<String, Object> hints) {
-		return Mono.just(customizeReader(reader, mimeType, elementType, hints));
+		return customizeReader(objectReader, elementType, hints);
 	}
 
 	/**
-	 * Provides the ability for subclasses to customize the {@link ObjectReader} for deserialization.
-	 * @param reader the {@link ObjectReader} available for customization
-	 * @param mimeType the MIME type associated with the input stream
-	 * @param elementType the expected type of elements in the output stream
-	 * @param hints additional information about how to do encode
-	 * @return the customized {@link ObjectReader}
+	 * Subclasses can use this method to customize {@link ObjectReader} used
+	 * for reading values.
+	 * @param reader the reader instance to customize
+	 * @param elementType the target type of element values to read to
+	 * @param hints a map with serialization hints;
+	 * the Reactor Context, when available, may be accessed under the key
+	 * {@code ContextView.class.getName()}
+	 * @return the customized {@code ObjectReader} to use
+	 * @since 6.0
 	 */
-	protected ObjectReader customizeReader(@NonNull ObjectReader reader, @Nullable MimeType mimeType,
-			ResolvableType elementType, @Nullable Map<String, Object> hints) {
+	protected ObjectReader customizeReader(
+			ObjectReader reader, ResolvableType elementType, @Nullable Map<String, Object> hints) {
+
 		return reader;
 	}
 
@@ -312,10 +292,6 @@ public abstract class AbstractJackson2Decoder extends Jackson2CodecSupport imple
 		return getMimeTypes();
 	}
 
-	@Override
-	public List<MimeType> getDecodableMimeTypes(ResolvableType targetType) {
-		return getMimeTypes(targetType);
-	}
 
 	// Jackson2CodecSupport
 

spring-web/src/main/java/org/springframework/http/codec/json/AbstractJackson2Encoder.java

@@ -39,6 +39,7 @@ import com.fasterxml.jackson.databind.ser.FilterProvider;
 import org.reactivestreams.Publisher;
 import reactor.core.publisher.Flux;
 import reactor.core.publisher.Mono;
+import reactor.util.context.ContextView;
 
 import org.springframework.core.MethodParameter;
 import org.springframework.core.ResolvableType;
@@ -53,7 +54,6 @@ import org.springframework.http.codec.HttpMessageEncoder;
 import org.springframework.http.converter.json.MappingJacksonValue;
 import org.springframework.http.server.reactive.ServerHttpRequest;
 import org.springframework.http.server.reactive.ServerHttpResponse;
-import org.springframework.lang.NonNull;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
@@ -87,6 +87,7 @@ public abstract class AbstractJackson2Encoder extends Jackson2CodecSupport imple
 
 	private final List<MediaType> streamingMediaTypes = new ArrayList<>(1);
 
+
 	/**
 	 * Constructor with a Jackson {@link ObjectMapper} to use.
 	 */
@@ -148,89 +149,95 @@ public abstract class AbstractJackson2Encoder extends Jackson2CodecSupport imple
 		Assert.notNull(bufferFactory, "'bufferFactory' must not be null");
 		Assert.notNull(elementType, "'elementType' must not be null");
 
-		if (inputStream instanceof Mono) {
-			return Mono.from(inputStream)
-					.flatMap(value -> createEncodingToolsForStream(value, elementType, mimeType, hints)
-							.map(tools -> encodeValue(value, tools.mapper(), tools.writer(),
-									bufferFactory, mimeType, hints)))
-					.flux();
-		}
+		return Flux.deferContextual(contextView -> {
 
-		try {
-			ObjectMapper mapper = selectObjectMapper(elementType, mimeType);
-			if (mapper == null) {
-				throw new IllegalStateException("No ObjectMapper for " + elementType);
-			}
-			ObjectWriter writer = createObjectWriter(mapper, elementType, mimeType, null, hints);
-			ByteArrayBuilder byteBuilder = new ByteArrayBuilder(writer.getFactory()._getBufferRecycler());
-			JsonEncoding encoding = getJsonEncoding(mimeType);
-			JsonGenerator generator = mapper.getFactory().createGenerator(byteBuilder, encoding);
-			SequenceWriter sequenceWriter = writer.writeValues(generator);
-
-			byte[] separator = getStreamingMediaTypeSeparator(mimeType);
-			Flux<DataBuffer> dataBufferFlux;
+			Map<String, Object> hintsToUse = contextView.isEmpty() ? hints :
+					Hints.merge(hints, ContextView.class.getName(), contextView);
 
-			if (separator != null) {
-				dataBufferFlux = Flux.from(inputStream).map(value -> encodeStreamingValue(
-						value, bufferFactory, hints, sequenceWriter, byteBuilder, EMPTY_BYTES, separator));
+			if (inputStream instanceof Mono) {
+				return Mono.from(inputStream)
+						.map(value -> encodeValue(value, bufferFactory, elementType, mimeType, hintsToUse))
+						.flux();
 			}
-			else {
-				JsonArrayJoinHelper helper = new JsonArrayJoinHelper();
-
-				// Do not prepend JSON array prefix until first signal is known, onNext vs onError
-				// Keeps response not committed for error handling
-
-				dataBufferFlux = Flux.from(inputStream)
-						.map(value -> {
-							byte[] prefix = helper.getPrefix();
-							byte[] delimiter = helper.getDelimiter();
-
-							DataBuffer dataBuffer = encodeStreamingValue(
-									value, bufferFactory, hints, sequenceWriter, byteBuilder, delimiter, EMPTY_BYTES);
-
-							return (prefix.length > 0 ?
-									bufferFactory.join(Arrays.asList(bufferFactory.wrap(prefix), dataBuffer)) :
-									dataBuffer);
-						})
-						.concatWith(Mono.fromCallable(() -> bufferFactory.wrap(helper.getSuffix())));
 
+			try {
+				ObjectMapper mapper = selectObjectMapper(elementType, mimeType);
+				if (mapper == null) {
+					throw new IllegalStateException("No ObjectMapper for " + elementType);
+				}
+
+				ObjectWriter writer = createObjectWriter(mapper, elementType, mimeType, null, hintsToUse);
+				ByteArrayBuilder byteBuilder = new ByteArrayBuilder(writer.getFactory()._getBufferRecycler());
+				JsonEncoding encoding = getJsonEncoding(mimeType);
+				JsonGenerator generator = mapper.getFactory().createGenerator(byteBuilder, encoding);
+				SequenceWriter sequenceWriter = writer.writeValues(generator);
+
+				byte[] separator = getStreamingMediaTypeSeparator(mimeType);
+				Flux<DataBuffer> dataBufferFlux;
+
+				if (separator != null) {
+					dataBufferFlux = Flux.from(inputStream).map(value -> encodeStreamingValue(
+							value, bufferFactory, hintsToUse, sequenceWriter, byteBuilder, EMPTY_BYTES, separator));
+				}
+				else {
+					JsonArrayJoinHelper helper = new JsonArrayJoinHelper();
+
+					// Do not prepend JSON array prefix until first signal is known, onNext vs onError
+					// Keeps response not committed for error handling
+
+					dataBufferFlux = Flux.from(inputStream)
+							.map(value -> {
+								byte[] prefix = helper.getPrefix();
+								byte[] delimiter = helper.getDelimiter();
+
+								DataBuffer dataBuffer = encodeStreamingValue(
+										value, bufferFactory, hintsToUse, sequenceWriter, byteBuilder,
+										delimiter, EMPTY_BYTES);
+
+								return (prefix.length > 0 ?
+										bufferFactory.join(Arrays.asList(bufferFactory.wrap(prefix), dataBuffer)) :
+										dataBuffer);
+							})
+							.concatWith(Mono.fromCallable(() -> bufferFactory.wrap(helper.getSuffix())));
+				}
+
+				return dataBufferFlux
+						.doOnNext(dataBuffer ->	Hints.touchDataBuffer(dataBuffer, hintsToUse, logger))
+						.doAfterTerminate(() -> {
+							try {
+								byteBuilder.release();
+								generator.close();
+							}
+							catch (IOException ex) {
+								logger.error("Could not close Encoder resources", ex);
+							}
+						});
 			}
-
-			return dataBufferFlux
-					.doOnNext(dataBuffer ->	Hints.touchDataBuffer(dataBuffer, hints, logger))
-					.doAfterTerminate(() -> {
-						try {
-							byteBuilder.release();
-							generator.close();
-						}
-						catch (IOException ex) {
-							logger.error("Could not close Encoder resources", ex);
-						}
-					});
-		}
-		catch (IOException ex) {
-			return Flux.error(ex);
-		}
+			catch (IOException ex) {
+				return Flux.error(ex);
+			}
+		});
 	}
 
 	@Override
 	public DataBuffer encodeValue(Object value, DataBufferFactory bufferFactory,
 			ResolvableType valueType, @Nullable MimeType mimeType, @Nullable Map<String, Object> hints) {
-		ObjectEncodingTools encodingTools = createEncodingTools(value, valueType, mimeType, hints);
-		ObjectWriter writer = encodingTools.writer();
-		writer = customizeWriter(writer, mimeType, valueType, hints);
-		return encodeValue(value, encodingTools.mapper(), writer, bufferFactory, mimeType, hints);
-	}
-
-	private DataBuffer encodeValue(Object value, ObjectMapper mapper, ObjectWriter writer,
-			DataBufferFactory bufferFactory, @Nullable MimeType mimeType, @Nullable Map<String, Object> hints) {
 
+		Class<?> jsonView = null;
 		FilterProvider filters = null;
 		if (value instanceof MappingJacksonValue mappingJacksonValue) {
 			value = mappingJacksonValue.getValue();
+			valueType = ResolvableType.forInstance(value);
+			jsonView = mappingJacksonValue.getSerializationView();
 			filters = mappingJacksonValue.getFilters();
 		}
 
+		ObjectMapper mapper = selectObjectMapper(valueType, mimeType);
+		if (mapper == null) {
+			throw new IllegalStateException("No ObjectMapper for " + valueType);
+		}
+
+		ObjectWriter writer = createObjectWriter(mapper, valueType, mimeType, jsonView, hints);
 		if (filters != null) {
 			writer = writer.with(filters);
 		}
@@ -324,35 +331,6 @@ public abstract class AbstractJackson2Encoder extends Jackson2CodecSupport imple
 		}
 	}
 
-	private Mono<ObjectEncodingTools> createEncodingToolsForStream(Object value, ResolvableType valueType,
-			@Nullable MimeType mimeType, @Nullable Map<String, Object> hints) {
-		try {
-			ObjectEncodingTools encodingTools = createEncodingTools(value, valueType, mimeType, hints);
-			ObjectWriter objectWriter = encodingTools.writer();
-			return customizeWriterFromStream(objectWriter, mimeType, valueType, hints)
-					.map(customizedWriter -> new ObjectEncodingTools(encodingTools.mapper(), customizedWriter));
-		}
-		catch (IllegalStateException ex) {
-			return Mono.error(ex);
-		}
-	}
-
-	private ObjectEncodingTools createEncodingTools(Object value, ResolvableType valueType,
-			@Nullable MimeType mimeType, @Nullable Map<String, Object> hints) {
-		Class<?> jsonView = null;
-		if (value instanceof MappingJacksonValue mappingJacksonValue) {
-			valueType = ResolvableType.forInstance(mappingJacksonValue.getValue());
-			jsonView = mappingJacksonValue.getSerializationView();
-		}
-
-		ObjectMapper mapper = selectObjectMapper(valueType, mimeType);
-		if (mapper == null) {
-			throw new IllegalStateException("No ObjectMapper for " + valueType);
-		}
-		ObjectWriter writer = createObjectWriter(mapper, valueType, mimeType, jsonView, hints);
-		return new ObjectEncodingTools(mapper, writer);
-	}
-
 	private ObjectWriter createObjectWriter(
 			ObjectMapper mapper, ResolvableType valueType, @Nullable MimeType mimeType,
 			@Nullable Class<?> jsonView, @Nullable Map<String, Object> hints) {
@@ -365,32 +343,23 @@ public abstract class AbstractJackson2Encoder extends Jackson2CodecSupport imple
 		if (javaType.isContainerType()) {
 			writer = writer.forType(javaType);
 		}
-		return writer;
+		return customizeWriter(writer, mimeType, valueType, hints);
 	}
 
 	/**
-	 * Provides the ability for subclasses to customize the {@link ObjectWriter} for serialization from a stream.
-	 * @param writer the {@link ObjectWriter} available for customization
-	 * @param mimeType the MIME type associated with the input stream
-	 * @param elementType the expected type of elements in the output stream
-	 * @param hints additional information about how to do encode
-	 * @return the customized {@link ObjectWriter}
-	 */
-	protected Mono<ObjectWriter> customizeWriterFromStream(@NonNull ObjectWriter writer, @Nullable MimeType mimeType,
-			ResolvableType elementType, @Nullable Map<String, Object> hints) {
-		return Mono.just(customizeWriter(writer, mimeType, elementType, hints));
-	}
-
-	/**
-	 * Provides the ability for subclasses to customize the {@link ObjectWriter} for serialization.
-	 * @param writer the {@link ObjectWriter} available for customization
-	 * @param mimeType the MIME type associated with the input stream
-	 * @param elementType the expected type of elements in the output stream
-	 * @param hints additional information about how to do encode
-	 * @return the customized {@link ObjectWriter}
+	 * Subclasses can use this method to customize {@link ObjectWriter} used
+	 * for writing values.
+	 * @param writer the writer instance to customize
+	 * @param mimeType the selected MIME type
+	 * @param elementType the type of element values to write
+	 * @param hints a map with serialization hints;
+	 * the Reactor Context, when available, may be accessed under the key
+	 * {@code ContextView.class.getName()}
+	 * @return the customized {@code ObjectWriter} to use
 	 */
 	protected ObjectWriter customizeWriter(ObjectWriter writer, @Nullable MimeType mimeType,
 			ResolvableType elementType, @Nullable Map<String, Object> hints) {
+
 		return writer;
 	}
 
@@ -489,8 +458,4 @@ public abstract class AbstractJackson2Encoder extends Jackson2CodecSupport imple
 		}
 	}
 
-
-	private record ObjectEncodingTools(ObjectMapper mapper, ObjectWriter writer) {
-	}
-
 }

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

@@ -59,7 +59,6 @@ import org.springframework.http.converter.HttpMessageConversionException;
 import org.springframework.http.converter.HttpMessageConverter;
 import org.springframework.http.converter.HttpMessageNotReadableException;
 import org.springframework.http.converter.HttpMessageNotWritableException;
-import org.springframework.lang.NonNull;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
@@ -411,12 +410,14 @@ public abstract class AbstractJackson2HttpMessageConverter extends AbstractGener
 	}
 
 	/**
-	 * Provides the ability for subclasses to customize the {@link ObjectReader} for deserialization.
-	 * @param reader the {@link ObjectReader} available for customization
-	 * @param javaType the specified type to deserialize to
+	 * Subclasses can use this method to customize {@link ObjectReader} used
+	 * for reading values.
+	 * @param reader the reader instance to customize
+	 * @param javaType the target type of element values to read to
 	 * @return the customized {@link ObjectReader}
+	 * @since 6.0
 	 */
-	protected ObjectReader customizeReader(@NonNull ObjectReader reader, JavaType javaType) {
+	protected ObjectReader customizeReader(ObjectReader reader, JavaType javaType) {
 		return reader;
 	}
 
@@ -495,14 +496,17 @@ public abstract class AbstractJackson2HttpMessageConverter extends AbstractGener
 	}
 
 	/**
-	 * Provides the ability for subclasses to customize the {@link ObjectWriter} for serialization.
-	 * @param writer the {@link ObjectWriter} available for customization
-	 * @param javaType the specified type to serialize from
-	 * @param contentType the output content type
+	 * Subclasses can use this method to customize {@link ObjectWriter} used
+	 * for writing values.
+	 * @param writer the writer instance to customize
+	 * @param javaType the type of element values to write
+	 * @param contentType the selected media type
 	 * @return the customized {@link ObjectWriter}
+	 * @since 6.0
 	 */
-	protected ObjectWriter customizeWriter(@NonNull ObjectWriter writer, @Nullable JavaType javaType,
-			@Nullable MediaType contentType) {
+	protected ObjectWriter customizeWriter(
+			ObjectWriter writer, @Nullable JavaType javaType, @Nullable MediaType contentType) {
+
 		return writer;
 	}
 

spring-web/src/test/java/org/springframework/http/codec/json/CustomizedJackson2JsonDecoderTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2022 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.
@@ -29,7 +29,6 @@ import reactor.core.publisher.Mono;
 import org.springframework.core.ResolvableType;
 import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.core.testfixture.codec.AbstractDecoderTests;
-import org.springframework.util.MimeType;
 
 /**
  * Unit tests for a customized {@link Jackson2JsonDecoder}.
@@ -83,7 +82,8 @@ public class CustomizedJackson2JsonDecoderTests extends AbstractDecoderTests<Jac
 		});
 	}
 
-	public static class MyCustomizedDecoderBean {
+
+	private static class MyCustomizedDecoderBean {
 
 		private MyCustomDecoderEnum property;
 
@@ -96,7 +96,8 @@ public class CustomizedJackson2JsonDecoderTests extends AbstractDecoderTests<Jac
 		}
 	}
 
-	public enum MyCustomDecoderEnum {
+
+	private enum MyCustomDecoderEnum {
 		VAL1,
 		VAL2;
 
@@ -106,16 +107,15 @@ public class CustomizedJackson2JsonDecoderTests extends AbstractDecoderTests<Jac
 		}
 	}
 
+
 	private static class Jackson2JsonDecoderWithCustomization extends Jackson2JsonDecoder {
 
 		@Override
-		protected Mono<ObjectReader> customizeReaderFromStream(ObjectReader reader, MimeType mimeType, ResolvableType elementType, Map<String, Object> hints) {
-			return Mono.just(reader.with(DeserializationFeature.READ_ENUMS_USING_TO_STRING));
-		}
+		protected ObjectReader customizeReader(
+				ObjectReader reader, ResolvableType elementType, Map<String, Object> hints) {
 
-		@Override
-		protected ObjectReader customizeReader(ObjectReader reader, MimeType mimeType, ResolvableType elementType, Map<String, Object> hints) {
 			return reader.with(DeserializationFeature.READ_ENUMS_USING_TO_STRING);
 		}
 	}
+
 }

spring-web/src/test/java/org/springframework/http/codec/json/CustomizedJackson2JsonEncoderTests.java

@@ -22,7 +22,6 @@ import com.fasterxml.jackson.databind.ObjectWriter;
 import com.fasterxml.jackson.databind.SerializationFeature;
 import org.junit.jupiter.api.Test;
 import reactor.core.publisher.Flux;
-import reactor.core.publisher.Mono;
 
 import org.springframework.core.ResolvableType;
 import org.springframework.core.io.buffer.DataBufferUtils;
@@ -71,14 +70,14 @@ public class CustomizedJackson2JsonEncoderTests extends AbstractEncoderTests<Jac
 		);
 
 		testEncode(input, MyCustomizedEncoderBean.class, step -> step
-				.consumeNextWith(expectString("[" +
-						"{\"property\":\"Value1\"}," +
-						"{\"property\":\"Value2\"}]")
-						.andThen(DataBufferUtils::release))
+				.consumeNextWith(expectString("[{\"property\":\"Value1\"}").andThen(DataBufferUtils::release))
+				.consumeNextWith(expectString(",{\"property\":\"Value2\"}").andThen(DataBufferUtils::release))
+				.consumeNextWith(expectString("]").andThen(DataBufferUtils::release))
 				.verifyComplete());
 	}
 
-	public static class MyCustomizedEncoderBean {
+
+	private static class MyCustomizedEncoderBean {
 
 		private MyCustomEncoderEnum property;
 
@@ -95,7 +94,8 @@ public class CustomizedJackson2JsonEncoderTests extends AbstractEncoderTests<Jac
 		}
 	}
 
-	public enum MyCustomEncoderEnum {
+
+	private enum MyCustomEncoderEnum {
 		VAL1,
 		VAL2;
 
@@ -105,16 +105,15 @@ public class CustomizedJackson2JsonEncoderTests extends AbstractEncoderTests<Jac
 		}
 	}
 
+
 	private static class Jackson2JsonEncoderWithCustomization extends Jackson2JsonEncoder {
 
 		@Override
-		protected Mono<ObjectWriter> customizeWriterFromStream(ObjectWriter writer, MimeType mimeType, ResolvableType elementType, Map<String, Object> hints) {
-			return Mono.just(writer.with(SerializationFeature.WRITE_ENUMS_USING_TO_STRING));
-		}
+		protected ObjectWriter customizeWriter(
+				ObjectWriter writer, MimeType mimeType, ResolvableType elementType, Map<String, Object> hints) {
 
-		@Override
-		protected ObjectWriter customizeWriter(ObjectWriter writer, MimeType mimeType, ResolvableType elementType, Map<String, Object> hints) {
 			return writer.with(SerializationFeature.WRITE_ENUMS_USING_TO_STRING);
 		}
 	}
+
 }