/*
* Copyright 2002-2014 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
*
* http://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.xml;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.StringReader;
import java.util.HashSet;
import java.util.Set;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import javax.xml.transform.Result;
import javax.xml.transform.Source;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.sax.SAXSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.stream.StreamSource;
import org.w3c.dom.Document;
import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.springframework.http.HttpInputMessage;
import org.springframework.http.HttpOutputMessage;
import org.springframework.http.MediaType;
import org.springframework.http.converter.AbstractHttpMessageConverter;
import org.springframework.http.converter.HttpMessageConversionException;
import org.springframework.http.converter.HttpMessageNotReadableException;
import org.springframework.http.converter.HttpMessageNotWritableException;
import org.springframework.util.StreamUtils;
import android.os.Build;
/**
* Implementation of {@link org.springframework.http.converter.HttpMessageConverter}
* that can read and write {@link Source} objects.
*
* @author Arjen Poutsma
* @author Rossen Stoyanchev
* Roy Clarkson
* @since 1.0
*/
public class SourceHttpMessageConverter<T extends Source> extends AbstractHttpMessageConverter<T> {
private static final Set<Class<?>> SUPPORTED_CLASSES = new HashSet<Class<?>>(4);
static {
SUPPORTED_CLASSES.add(DOMSource.class);
SUPPORTED_CLASSES.add(SAXSource.class);
SUPPORTED_CLASSES.add(StreamSource.class);
SUPPORTED_CLASSES.add(Source.class);
}
private final TransformerFactory transformerFactory = TransformerFactory.newInstance();
private boolean processExternalEntities = false;
/**
* Sets the {@link #setSupportedMediaTypes(java.util.List) supportedMediaTypes}
* to {@code text/xml} and {@code application/xml}, and {@code application/*-xml}.
*/
public SourceHttpMessageConverter() {
super(MediaType.APPLICATION_XML, MediaType.TEXT_XML, new MediaType("application", "*+xml"));
}
/**
* Indicates whether external XML entities are processed when converting to a Source.
* <p>Default is {@code false}, meaning that external entities are not resolved.
*
* <p>Note: This feature is not supported when reading {@code DOMSource}
* entities and is only supported on Android 4.0 and newer when reading
* {@code SAXSource}.
*/
public void setProcessExternalEntities(boolean processExternalEntities) {
this.processExternalEntities = processExternalEntities;
}
/**
* Returns the configured value for whether XML external entities are allowed.
*/
public boolean isProcessExternalEntities() {
return this.processExternalEntities;
}
@Override
public boolean supports(Class<?> clazz) {
return SUPPORTED_CLASSES.contains(clazz);
}
@Override
@SuppressWarnings("unchecked")
protected T readInternal(Class<? extends T> clazz, HttpInputMessage inputMessage)
throws IOException, HttpMessageNotReadableException {
InputStream body = inputMessage.getBody();
if (DOMSource.class.equals(clazz)) {
return (T) readDOMSource(body);
}
else if (SAXSource.class.equals(clazz)) {
return (T) readSAXSource(body);
}
else if (StreamSource.class.equals(clazz) || Source.class.equals(clazz)) {
return (T) readStreamSource(body);
}
else {
throw new HttpMessageConversionException("Could not read class [" + clazz +
"]. Only DOMSource, SAXSource, and StreamSource are supported.");
}
}
private DOMSource readDOMSource(InputStream body) throws IOException {
try {
DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
documentBuilderFactory.setNamespaceAware(true);
DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();
if (!isProcessExternalEntities()) {
documentBuilder.setEntityResolver(NO_OP_ENTITY_RESOLVER);
}
Document document = documentBuilder.parse(body);
return new DOMSource(document);
}
catch (ParserConfigurationException ex) {
throw new HttpMessageNotReadableException("Could not set feature: " + ex.getMessage(), ex);
}
catch (SAXException ex) {
throw new HttpMessageNotReadableException("Could not parse document: " + ex.getMessage(), ex);
}
}
private SAXSource readSAXSource(InputStream body) throws IOException {
try {
// XMLReaderFactory.createXMLReader() is not working on Android
SAXParserFactory saxParserFactory = SAXParserFactory.newInstance();
SAXParser newSAXParser = saxParserFactory.newSAXParser();
XMLReader reader = newSAXParser.getXMLReader();
// older versions of the Android parser do not support this feature
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
reader.setFeature("http://xml.org/sax/features/external-general-entities", isProcessExternalEntities());
}
byte[] bytes = StreamUtils.copyToByteArray(body);
if (!isProcessExternalEntities()) {
reader.setEntityResolver(NO_OP_ENTITY_RESOLVER);
}
return new SAXSource(reader, new InputSource(new ByteArrayInputStream(bytes)));
}
catch (ParserConfigurationException ex) {
throw new HttpMessageNotReadableException("Could not parse document: " + ex.getMessage(), ex);
}
catch (SAXException ex) {
throw new HttpMessageNotReadableException("Could not parse document: " + ex.getMessage(), ex);
}
}
private StreamSource readStreamSource(InputStream body) throws IOException {
byte[] bytes = StreamUtils.copyToByteArray(body);
return new StreamSource(new ByteArrayInputStream(bytes));
}
@Override
protected Long getContentLength(T t, MediaType contentType) {
if (t instanceof DOMSource) {
try {
CountingOutputStream os = new CountingOutputStream();
transform(t, new StreamResult(os));
return os.count;
}
catch (TransformerException ex) {
// ignore
}
}
return null;
}
@Override
protected void writeInternal(T t, HttpOutputMessage outputMessage)
throws IOException, HttpMessageNotWritableException {
try {
Result result = new StreamResult(outputMessage.getBody());
transform(t, result);
}
catch (TransformerException ex) {
throw new HttpMessageNotWritableException("Could not transform [" + t + "] to output message", ex);
}
}
private void transform(Source source, Result result) throws TransformerException {
this.transformerFactory.newTransformer().transform(source, result);
}
private static class CountingOutputStream extends OutputStream {
long count = 0;
@Override
public void write(int b) throws IOException {
this.count++;
}
@Override
public void write(byte[] b) throws IOException {
this.count += b.length;
}
@Override
public void write(byte[] b, int off, int len) throws IOException {
this.count += len;
}
}
private static final EntityResolver NO_OP_ENTITY_RESOLVER = new EntityResolver() {
@Override
public InputSource resolveEntity(String publicId, String systemId) {
return new InputSource(new StringReader(""));
}
};
}