001/* 002 * Copyright 2002-2020 the original author or authors. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * https://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016 017package org.springframework.http.converter; 018 019import java.io.IOException; 020import java.util.List; 021 022import org.springframework.http.HttpInputMessage; 023import org.springframework.http.HttpOutputMessage; 024import org.springframework.http.MediaType; 025import org.springframework.lang.Nullable; 026 027/** 028 * Strategy interface for converting from and to HTTP requests and responses. 029 * 030 * @author Arjen Poutsma 031 * @author Juergen Hoeller 032 * @since 3.0 033 * @param <T> the converted object type 034 */ 035public interface HttpMessageConverter<T> { 036 037 /** 038 * Indicates whether the given class can be read by this converter. 039 * @param clazz the class to test for readability 040 * @param mediaType the media type to read (can be {@code null} if not specified); 041 * typically the value of a {@code Content-Type} header. 042 * @return {@code true} if readable; {@code false} otherwise 043 */ 044 boolean canRead(Class<?> clazz, @Nullable MediaType mediaType); 045 046 /** 047 * Indicates whether the given class can be written by this converter. 048 * @param clazz the class to test for writability 049 * @param mediaType the media type to write (can be {@code null} if not specified); 050 * typically the value of an {@code Accept} header. 051 * @return {@code true} if writable; {@code false} otherwise 052 */ 053 boolean canWrite(Class<?> clazz, @Nullable MediaType mediaType); 054 055 /** 056 * Return the list of {@link MediaType} objects supported by this converter. 057 * @return the list of supported media types, potentially an immutable copy 058 */ 059 List<MediaType> getSupportedMediaTypes(); 060 061 /** 062 * Read an object of the given type from the given input message, and returns it. 063 * @param clazz the type of object to return. This type must have previously been passed to the 064 * {@link #canRead canRead} method of this interface, which must have returned {@code true}. 065 * @param inputMessage the HTTP input message to read from 066 * @return the converted object 067 * @throws IOException in case of I/O errors 068 * @throws HttpMessageNotReadableException in case of conversion errors 069 */ 070 T read(Class<? extends T> clazz, HttpInputMessage inputMessage) 071 throws IOException, HttpMessageNotReadableException; 072 073 /** 074 * Write an given object to the given output message. 075 * @param t the object to write to the output message. The type of this object must have previously been 076 * passed to the {@link #canWrite canWrite} method of this interface, which must have returned {@code true}. 077 * @param contentType the content type to use when writing. May be {@code null} to indicate that the 078 * default content type of the converter must be used. If not {@code null}, this media type must have 079 * previously been passed to the {@link #canWrite canWrite} method of this interface, which must have 080 * returned {@code true}. 081 * @param outputMessage the message to write to 082 * @throws IOException in case of I/O errors 083 * @throws HttpMessageNotWritableException in case of conversion errors 084 */ 085 void write(T t, @Nullable MediaType contentType, HttpOutputMessage outputMessage) 086 throws IOException, HttpMessageNotWritableException; 087 088}