https://github.com/spring-projects/spring-framework: Spring Web (Spring IO)
  • Juergen Hoeller 
/*
 * Copyright 2002-2018 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.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.http.converter;

import java.io.IOException;
import java.lang.reflect.Type;

import org.springframework.http.HttpInputMessage;
import org.springframework.http.HttpOutputMessage;
import org.springframework.http.MediaType;
import org.springframework.lang.Nullable;


A specialization of HttpMessageConverter that can convert an HTTP request into a target object of a specified generic type and a source object of a specified generic type into an HTTP response. 
Author:Arjen Poutsma, Rossen Stoyanchev, Sebastien Deleuze
Type parameters:
  • <T> – the converted object type
See Also:
Since:3.2
/**
 * A specialization of {@link HttpMessageConverter} that can convert an HTTP request
 * into a target object of a specified generic type and a source object of a specified
 * generic type into an HTTP response.
 *
 * @author Arjen Poutsma
 * @author Rossen Stoyanchev
 * @author Sebastien Deleuze
 * @since 3.2
 * @param <T> the converted object type
 * @see org.springframework.core.ParameterizedTypeReference
 */
public interface GenericHttpMessageConverter<T> extends HttpMessageConverter<T> {

	
Indicates whether the given type can be read by this converter. This method should perform the same checks than HttpMessageConverter.canRead(Class, MediaType) with additional ones related to the generic type. 
Params:
  • type – the (potentially generic) type to test for readability
  • contextClass – a context class for the target type, for example a class in which the target type appears in a method signature (can be null)
  • mediaType – the media type to read, can be null if not specified. Typically the value of a Content-Type header.
Returns:true if readable; false otherwise
/**
	 * Indicates whether the given type can be read by this converter.
	 * This method should perform the same checks than
	 * {@link HttpMessageConverter#canRead(Class, MediaType)} with additional ones
	 * related to the generic type.
	 * @param type the (potentially generic) type to test for readability
	 * @param contextClass a context class for the target type, for example a class
	 * in which the target type appears in a method signature (can be {@code null})
	 * @param mediaType the media type to read, can be {@code null} if not specified.
	 * Typically the value of a {@code Content-Type} header.
	 * @return {@code true} if readable; {@code false} otherwise
	 */
	boolean canRead(Type type, @Nullable Class<?> contextClass, @Nullable MediaType mediaType);

	
Read an object of the given type form the given input message, and returns it.

Params:
  • type – the (potentially generic) type of object to return. This type must have previously been passed to the canRead method of this interface, which must have returned true.
  • contextClass – a context class for the target type, for example a class in which the target type appears in a method signature (can be null)
  • inputMessage – the HTTP input message to read from
Throws:
Returns:the converted object
/**
	 * Read an object of the given type form the given input message, and returns it.
	 * @param type the (potentially generic) type of object to return. This type must have
	 * previously been passed to the {@link #canRead canRead} method of this interface,
	 * which must have returned {@code true}.
	 * @param contextClass a context class for the target type, for example a class
	 * in which the target type appears in a method signature (can be {@code null})
	 * @param inputMessage the HTTP input message to read from
	 * @return the converted object
	 * @throws IOException in case of I/O errors
	 * @throws HttpMessageNotReadableException in case of conversion errors
	 */
	T read(Type type, @Nullable Class<?> contextClass, HttpInputMessage inputMessage)
			throws IOException, HttpMessageNotReadableException;

	
Indicates whether the given class can be written by this converter.

This method should perform the same checks than HttpMessageConverter.canWrite(Class, MediaType) with additional ones related to the generic type. 
Params:
  • type – the (potentially generic) type to test for writability (can be null if not specified)
  • clazz – the source object class to test for writability
  • mediaType – the media type to write (can be null if not specified); typically the value of an Accept header.
Returns:true if writable; false otherwise
Since:4.2
/**
	 * Indicates whether the given class can be written by this converter.
	 * <p>This method should perform the same checks than
	 * {@link HttpMessageConverter#canWrite(Class, MediaType)} with additional ones
	 * related to the generic type.
	 * @param type the (potentially generic) type to test for writability
	 * (can be {@code null} if not specified)
	 * @param clazz the source object class to test for writability
	 * @param mediaType the media type to write (can be {@code null} if not specified);
	 * typically the value of an {@code Accept} header.
	 * @return {@code true} if writable; {@code false} otherwise
	 * @since 4.2
	 */
	boolean canWrite(@Nullable Type type, Class<?> clazz, @Nullable MediaType mediaType);

	
Write an given object to the given output message.

Params:
  • t – the object to write to the output message. The type of this object must have previously been passed to the canWrite method of this interface, which must have returned true.
  • type – the (potentially generic) type of object to write. This type must have previously been passed to the canWrite method of this interface, which must have returned true. Can be null if not specified.
  • contentType – the content type to use when writing. May be null to indicate that the default content type of the converter must be used. If not null, this media type must have previously been passed to the canWrite method of this interface, which must have returned true.
  • outputMessage – the message to write to
Throws:
Since:4.2
/**
	 * Write an given object to the given output message.
	 * @param t the object to write to the output message. The type of this object must
	 * have previously been passed to the {@link #canWrite canWrite} method of this
	 * interface, which must have returned {@code true}.
	 * @param type the (potentially generic) type of object to write. This type must have
	 * previously been passed to the {@link #canWrite canWrite} method of this interface,
	 * which must have returned {@code true}. Can be {@code null} if not specified.
	 * @param contentType the content type to use when writing. May be {@code null} to
	 * indicate that the default content type of the converter must be used. If not
	 * {@code null}, this media type must have previously been passed to the
	 * {@link #canWrite canWrite} method of this interface, which must have returned
	 * {@code true}.
	 * @param outputMessage the message to write to
	 * @throws IOException in case of I/O errors
	 * @throws HttpMessageNotWritableException in case of conversion errors
	 * @since 4.2
	 */
	void write(T t, @Nullable Type type, @Nullable MediaType contentType, HttpOutputMessage outputMessage)
			throws IOException, HttpMessageNotWritableException;

}