Java tutorial
/* * eXist Open Source Native XML Database * Copyright (C) 2001-09 Wolfgang M. Meier * wolfgang@exist-db.org * http://exist.sourceforge.net * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public License * as published by the Free Software Foundation; either version 2 * of the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. * * $Id$ */ package org.exist.xquery.functions.request; import java.io.IOException; import java.io.InputStream; import org.apache.commons.io.input.CloseShieldInputStream; import org.apache.log4j.Logger; import org.exist.Namespaces; import org.exist.dom.QName; import org.apache.commons.io.output.ByteArrayOutputStream; import org.exist.http.servlets.RequestWrapper; import org.exist.memtree.DocumentBuilderReceiver; import org.exist.memtree.MemTreeBuilder; import org.exist.util.Configuration; import org.exist.util.MimeTable; import org.exist.util.MimeType; import org.exist.util.io.CachingFilterInputStream; import org.exist.util.io.FilterInputStreamCache; import org.exist.util.io.FilterInputStreamCacheFactory; import org.exist.util.io.FilterInputStreamCacheFactory.FilterInputStreamCacheConfiguration; import org.exist.xquery.*; import org.exist.xquery.value.*; import org.w3c.dom.Document; import org.xml.sax.InputSource; import org.xml.sax.SAXException; import org.xml.sax.XMLReader; /** * @author Wolfgang Meier <wolfgang@exist-db.org> * @author Adam retter <adam@exist-db.org> */ public class GetData extends BasicFunction { protected static final Logger logger = Logger.getLogger(GetData.class); public final static FunctionSignature signature = new FunctionSignature( new QName("get-data", RequestModule.NAMESPACE_URI, RequestModule.PREFIX), "Returns the content of a POST request. " + "If the HTTP Content-Type header in the request identifies it as a binary document, then xs:base64Binary is returned. " + "If its not a binary document, we attempt to parse it as XML and return a document-node(). " + "If its not a binary or XML document, any other data type is returned as an xs:string representation or " + "an empty sequence if there is no data to be read.", null, new FunctionReturnSequenceType(Type.ITEM, Cardinality.ZERO_OR_ONE, "the content of a POST request")); public GetData(XQueryContext context) { super(context, signature); } /* (non-Javadoc) * @see org.exist.xquery.BasicFunction#eval(org.exist.xquery.value.Sequence[], org.exist.xquery.value.Sequence) */ @Override public Sequence eval(Sequence[] args, Sequence contextSequence) throws XPathException { final RequestModule myModule = (RequestModule) context.getModule(RequestModule.NAMESPACE_URI); // request object is read from global variable $request final Variable var = myModule.resolveVariable(RequestModule.REQUEST_VAR); if (var == null || var.getValue() == null) { throw new XPathException(this, "No request object found in the current XQuery context."); } if (var.getValue().getItemType() != Type.JAVA_OBJECT) { throw new XPathException(this, "Variable $request is not bound to an Java object."); } final JavaObjectValue value = (JavaObjectValue) var.getValue().itemAt(0); if (!(value.getObject() instanceof RequestWrapper)) { throw new XPathException(this, "Variable $request is not bound to a Request object."); } final RequestWrapper request = (RequestWrapper) value.getObject(); //if the content length is unknown or 0, return if (request.getContentLength() == -1 || request.getContentLength() == 0) { return Sequence.EMPTY_SEQUENCE; } InputStream isRequest = null; Sequence result = Sequence.EMPTY_SEQUENCE; try { isRequest = request.getInputStream(); //was there any POST content? /** * There is a bug in HttpInput.available() in Jetty 7.2.2.v20101205 * This has been filed as Bug 333415 - https://bugs.eclipse.org/bugs/show_bug.cgi?id=333415 * It is expected to be fixed in the Jetty 7.3.0 release */ //TODO reinstate call to .available() when Jetty 7.3.0 is released, use of .getContentLength() is not reliable because of http mechanics //if(is != null && is.available() > 0) { if (isRequest != null && request.getContentLength() > 0) { // 1) determine if exists mime database considers this binary data String contentType = request.getContentType(); if (contentType != null) { //strip off any charset encoding info if (contentType.indexOf(";") > -1) { contentType = contentType.substring(0, contentType.indexOf(";")); } final MimeType mimeType = MimeTable.getInstance().getContentType(contentType); if (mimeType != null && !mimeType.isXMLType()) { //binary data result = BinaryValueFromInputStream.getInstance(context, new Base64BinaryValueType(), isRequest); } } if (result == Sequence.EMPTY_SEQUENCE) { //2) not binary, try and parse as an XML documemnt, otherwise 3) return a string representation //parsing will consume the stream so we must cache! InputStream is = null; FilterInputStreamCache cache = null; try { //we have to cache the input stream, so we can reread it, as we may use it twice (once for xml attempt and once for string attempt) cache = FilterInputStreamCacheFactory .getCacheInstance(new FilterInputStreamCacheConfiguration() { @Override public String getCacheClass() { return (String) context.getBroker().getConfiguration() .getProperty(Configuration.BINARY_CACHE_CLASS_PROPERTY); } }); is = new CachingFilterInputStream(cache, isRequest); //mark the start of the stream is.mark(Integer.MAX_VALUE); //2) try and parse as XML result = parseAsXml(is); if (result == Sequence.EMPTY_SEQUENCE) { // 3) not a valid XML document, return a string representation of the document String encoding = request.getCharacterEncoding(); if (encoding == null) { encoding = "UTF-8"; } try { //reset the stream, as we need to reuse for string parsing after the XML parsing happened is.reset(); result = parseAsString(is, encoding); } catch (final IOException ioe) { throw new XPathException(this, "An IO exception occurred: " + ioe.getMessage(), ioe); } } } finally { if (cache != null) { try { cache.invalidate(); } catch (final IOException ioe) { LOG.error(ioe.getMessage(), ioe); } } if (is != null) { try { is.close(); } catch (final IOException ioe) { LOG.error(ioe.getMessage(), ioe); } } } } //NOTE we do not close isRequest, because it may be needed further by the caching input stream wrapper } } catch (final IOException ioe) { throw new XPathException(this, "An IO exception occurred: " + ioe.getMessage(), ioe); } return result; } private Sequence parseAsXml(InputStream is) { Sequence result = Sequence.EMPTY_SEQUENCE; XMLReader reader = null; context.pushDocumentContext(); try { //try and construct xml document from input stream, we use eXist's in-memory DOM implementation //we have to use CloseShieldInputStream otherwise the parser closes the stream and we cant later reread final InputSource src = new InputSource(new CloseShieldInputStream(is)); reader = context.getBroker().getBrokerPool().getParserPool().borrowXMLReader(); final MemTreeBuilder builder = context.getDocumentBuilder(); final DocumentBuilderReceiver receiver = new DocumentBuilderReceiver(builder, true); reader.setContentHandler(receiver); reader.setProperty(Namespaces.SAX_LEXICAL_HANDLER, receiver); reader.parse(src); final Document doc = receiver.getDocument(); result = (NodeValue) doc; } catch (final SAXException saxe) { //do nothing, we will default to trying to return a string below } catch (final IOException ioe) { //do nothing, we will default to trying to return a string below } finally { context.popDocumentContext(); if (reader != null) { context.getBroker().getBrokerPool().getParserPool().returnXMLReader(reader); } } return result; } private Sequence parseAsString(InputStream is, String encoding) throws IOException { final ByteArrayOutputStream bos = new ByteArrayOutputStream(); final byte[] buf = new byte[4096]; int read = -1; while ((read = is.read(buf)) > -1) { bos.write(buf, 0, read); } final String s = new String(bos.toByteArray(), encoding); return new StringValue(s); } }