001/* 002 * Copyright 2002-2017 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.io.OutputStream; 021import java.lang.reflect.Type; 022 023import org.springframework.http.HttpHeaders; 024import org.springframework.http.HttpOutputMessage; 025import org.springframework.http.MediaType; 026import org.springframework.http.StreamingHttpOutputMessage; 027 028/** 029 * Abstract base class for most {@link GenericHttpMessageConverter} implementations. 030 * 031 * @author Sebastien Deleuze 032 * @author Juergen Hoeller 033 * @since 4.2 034 */ 035public abstract class AbstractGenericHttpMessageConverter<T> extends AbstractHttpMessageConverter<T> 036 implements GenericHttpMessageConverter<T> { 037 038 /** 039 * Construct an {@code AbstractGenericHttpMessageConverter} with no supported media types. 040 * @see #setSupportedMediaTypes 041 */ 042 protected AbstractGenericHttpMessageConverter() { 043 } 044 045 /** 046 * Construct an {@code AbstractGenericHttpMessageConverter} with one supported media type. 047 * @param supportedMediaType the supported media type 048 */ 049 protected AbstractGenericHttpMessageConverter(MediaType supportedMediaType) { 050 super(supportedMediaType); 051 } 052 053 /** 054 * Construct an {@code AbstractGenericHttpMessageConverter} with multiple supported media type. 055 * @param supportedMediaTypes the supported media types 056 */ 057 protected AbstractGenericHttpMessageConverter(MediaType... supportedMediaTypes) { 058 super(supportedMediaTypes); 059 } 060 061 062 @Override 063 protected boolean supports(Class<?> clazz) { 064 return true; 065 } 066 067 @Override 068 public boolean canRead(Type type, Class<?> contextClass, MediaType mediaType) { 069 return (type instanceof Class ? canRead((Class<?>) type, mediaType) : canRead(mediaType)); 070 } 071 072 @Override 073 public boolean canWrite(Type type, Class<?> clazz, MediaType mediaType) { 074 return canWrite(clazz, mediaType); 075 } 076 077 /** 078 * This implementation sets the default headers by calling {@link #addDefaultHeaders}, 079 * and then calls {@link #writeInternal}. 080 */ 081 public final void write(final T t, final Type type, MediaType contentType, HttpOutputMessage outputMessage) 082 throws IOException, HttpMessageNotWritableException { 083 084 final HttpHeaders headers = outputMessage.getHeaders(); 085 addDefaultHeaders(headers, t, contentType); 086 087 if (outputMessage instanceof StreamingHttpOutputMessage) { 088 StreamingHttpOutputMessage streamingOutputMessage = (StreamingHttpOutputMessage) outputMessage; 089 streamingOutputMessage.setBody(new StreamingHttpOutputMessage.Body() { 090 @Override 091 public void writeTo(final OutputStream outputStream) throws IOException { 092 writeInternal(t, type, new HttpOutputMessage() { 093 @Override 094 public OutputStream getBody() throws IOException { 095 return outputStream; 096 } 097 @Override 098 public HttpHeaders getHeaders() { 099 return headers; 100 } 101 }); 102 } 103 }); 104 } 105 else { 106 writeInternal(t, type, outputMessage); 107 outputMessage.getBody().flush(); 108 } 109 } 110 111 @Override 112 protected void writeInternal(T t, HttpOutputMessage outputMessage) 113 throws IOException, HttpMessageNotWritableException { 114 115 writeInternal(t, null, outputMessage); 116 } 117 118 /** 119 * Abstract template method that writes the actual body. Invoked from {@link #write}. 120 * @param t the object to write to the output message 121 * @param type the type of object to write (may be {@code null}) 122 * @param outputMessage the HTTP output message to write to 123 * @throws IOException in case of I/O errors 124 * @throws HttpMessageNotWritableException in case of conversion errors 125 */ 126 protected abstract void writeInternal(T t, Type type, HttpOutputMessage outputMessage) 127 throws IOException, HttpMessageNotWritableException; 128 129}