001/*
002 * Copyright 2002-2018 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.xml;
018
019import java.io.IOException;
020import javax.xml.transform.Result;
021import javax.xml.transform.Source;
022import javax.xml.transform.TransformerException;
023import javax.xml.transform.TransformerFactory;
024import javax.xml.transform.stream.StreamResult;
025import javax.xml.transform.stream.StreamSource;
026
027import org.springframework.http.HttpHeaders;
028import org.springframework.http.HttpInputMessage;
029import org.springframework.http.HttpOutputMessage;
030import org.springframework.http.MediaType;
031import org.springframework.http.converter.AbstractHttpMessageConverter;
032import org.springframework.http.converter.HttpMessageNotReadableException;
033import org.springframework.http.converter.HttpMessageNotWritableException;
034
035/**
036 * Abstract base class for {@link org.springframework.http.converter.HttpMessageConverter HttpMessageConverters}
037 * that convert from/to XML.
038 *
039 * <p>By default, subclasses of this converter support {@code text/xml}, {@code application/xml}, and {@code
040 * application/*-xml}. This can be overridden by setting the {@link #setSupportedMediaTypes(java.util.List)
041 * supportedMediaTypes} property.
042 *
043 * @author Arjen Poutsma
044 * @since 3.0
045 */
046public abstract class AbstractXmlHttpMessageConverter<T> extends AbstractHttpMessageConverter<T> {
047
048        private final TransformerFactory transformerFactory = TransformerFactory.newInstance();
049
050
051        /**
052         * Protected constructor that sets the {@link #setSupportedMediaTypes(java.util.List) supportedMediaTypes}
053         * to {@code text/xml} and {@code application/xml}, and {@code application/*-xml}.
054         */
055        protected AbstractXmlHttpMessageConverter() {
056                super(MediaType.APPLICATION_XML, MediaType.TEXT_XML, new MediaType("application", "*+xml"));
057        }
058
059
060        @Override
061        public final T readInternal(Class<? extends T> clazz, HttpInputMessage inputMessage)
062                        throws IOException, HttpMessageNotReadableException {
063
064                return readFromSource(clazz, inputMessage.getHeaders(), new StreamSource(inputMessage.getBody()));
065        }
066
067        @Override
068        protected final void writeInternal(T t, HttpOutputMessage outputMessage)
069                        throws IOException, HttpMessageNotWritableException {
070
071                writeToResult(t, outputMessage.getHeaders(), new StreamResult(outputMessage.getBody()));
072        }
073
074        /**
075         * Transforms the given {@code Source} to the {@code Result}.
076         * @param source the source to transform from
077         * @param result the result to transform to
078         * @throws TransformerException in case of transformation errors
079         */
080        protected void transform(Source source, Result result) throws TransformerException {
081                this.transformerFactory.newTransformer().transform(source, result);
082        }
083
084
085        /**
086         * Abstract template method called from {@link #read(Class, HttpInputMessage)}.
087         * @param clazz the type of object to return
088         * @param headers the HTTP input headers
089         * @param source the HTTP input body
090         * @return the converted object
091         * @throws IOException in case of I/O errors
092         * @throws HttpMessageNotReadableException in case of conversion errors
093         */
094        protected abstract T readFromSource(Class<? extends T> clazz, HttpHeaders headers, Source source)
095                        throws IOException, HttpMessageNotReadableException;
096
097        /**
098         * Abstract template method called from {@link #writeInternal(Object, HttpOutputMessage)}.
099         * @param t the object to write to the output message
100         * @param headers the HTTP output headers
101         * @param result the HTTP output body
102         * @throws IOException in case of I/O errors
103         * @throws HttpMessageNotWritableException in case of conversion errors
104         */
105        protected abstract void writeToResult(T t, HttpHeaders headers, Result result)
106                        throws IOException, HttpMessageNotWritableException;
107
108}