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: GetData.java 9749 2009-08-09 23:18:12Z ixitar $ */ package org.atombeat.xquery.functions.util; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.math.BigInteger; import java.security.DigestInputStream; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.exist.dom.QName; import org.exist.http.servlets.RequestWrapper; import org.exist.xquery.BasicFunction; import org.exist.xquery.Cardinality; import org.exist.xquery.FunctionSignature; import org.exist.xquery.Variable; import org.exist.xquery.XPathException; import org.exist.xquery.XQueryContext; import org.exist.xquery.functions.request.RequestModule; import org.exist.xquery.value.FunctionParameterSequenceType; import org.exist.xquery.value.FunctionReturnSequenceType; import org.exist.xquery.value.JavaObjectValue; import org.exist.xquery.value.Sequence; import org.exist.xquery.value.SequenceType; import org.exist.xquery.value.Type; import org.exist.xquery.value.StringValue; /** */ public class StreamRequestDataToFile extends BasicFunction { protected static final Log logger = LogFactory.getLog(StreamRequestDataToFile.class); public final static FunctionSignature signature = new FunctionSignature( new QName("stream-request-data-to-file", AtomBeatUtilModule.NAMESPACE_URI, AtomBeatUtilModule.PREFIX), "Streams the content of a POST request to a file. Returns true if the operation succeeded, otherwise false.", new SequenceType[] { new FunctionParameterSequenceType("path", Type.STRING, Cardinality.EXACTLY_ONE, "The file system path where the data is to be stored.") }, new FunctionReturnSequenceType(Type.STRING, Cardinality.ZERO_OR_ONE, "an MD5 digest of the content, or empty if there was a problem")); public StreamRequestDataToFile(XQueryContext context) { super(context, signature); } /* (non-Javadoc) * @see org.exist.xquery.BasicFunction#eval(org.exist.xquery.value.Sequence[], org.exist.xquery.value.Sequence) */ public Sequence eval(Sequence[] args, Sequence contextSequence) throws XPathException { logger.debug("begin stream request data to file eval"); logger.debug("access request module from context"); RequestModule reqModule = (RequestModule) context.getModule(RequestModule.NAMESPACE_URI); // request object is read from global variable $request Variable var = reqModule.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."); 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."); } logger.debug("access wrapped request"); RequestWrapper request = (RequestWrapper) value.getObject(); // we have to access the content-length header directly, rather than do request.getContentLength(), in case it's bigger than an int String contentLengthHeader = request.getHeader("Content-Length"); if (contentLengthHeader == null) { logger.debug("content length header is null, returning empty sequence"); return Sequence.EMPTY_SEQUENCE; } long contentLength = Long.parseLong(contentLengthHeader); logger.debug("content length via header: " + contentLength); logger.debug("request.getContentLength(): " + request.getContentLength()); // will be -1 if value is greater than an int // try to stream request content to file try { logger.debug("try to stream request data to file..."); logger.debug("open request input stream"); InputStream in = request.getInputStream(); MessageDigest md5 = MessageDigest.getInstance("MD5"); logger.debug("create digest input stream"); in = new DigestInputStream(in, md5); String path = args[0].getStringValue(); logger.debug("creating file at path: " + path); File file = new File(path); logger.debug("creating file output stream"); FileOutputStream out = new FileOutputStream(file); logger.debug("begin streaming data"); Stream.copy(in, out, contentLength); logger.debug("end streaming data"); logger.debug("create md5 signature"); String signature = new BigInteger(1, md5.digest()).toString(16); logger.debug("return signature"); return new StringValue(signature); } catch (IOException ioe) { throw new XPathException(this, "An IO exception ocurred: " + ioe.getMessage(), ioe); } catch (NoSuchAlgorithmException e) { throw new XPathException(this, "A message digest exception ocurred: " + e.getMessage(), e); } catch (Exception e) { throw new XPathException(this, "An unexpected exception ocurred: " + e.getMessage(), e); } } }