From 7439bd659e4befa5786b3455cf6ceb34825736e7 Mon Sep 17 00:00:00 2001
From: Jonathan Bauer
Date: Wed, 25 Apr 2018 18:35:04 +0200
Subject: [vbox] new XmlHelper class + usage thereof

---
 src/main/java/org/openslx/util/XmlHelper.java | 108 ++++++++++++++++++++++++++
 1 file changed, 108 insertions(+)
 create mode 100644 src/main/java/org/openslx/util/XmlHelper.java

(limited to 'src/main/java/org/openslx/util/XmlHelper.java')

diff --git a/src/main/java/org/openslx/util/XmlHelper.java b/src/main/java/org/openslx/util/XmlHelper.java
new file mode 100644
index 0000000..70c5be8
--- /dev/null
+++ b/src/main/java/org/openslx/util/XmlHelper.java
@@ -0,0 +1,108 @@
+package org.openslx.util;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.StringWriter;
+
+import javax.xml.parsers.DocumentBuilder;
+import javax.xml.parsers.DocumentBuilderFactory;
+import javax.xml.parsers.ParserConfigurationException;
+import javax.xml.transform.OutputKeys;
+import javax.xml.transform.Transformer;
+import javax.xml.transform.TransformerFactory;
+import javax.xml.transform.dom.DOMSource;
+import javax.xml.transform.stream.StreamResult;
+import javax.xml.xpath.XPath;
+import javax.xml.xpath.XPathConstants;
+import javax.xml.xpath.XPathExpressionException;
+import javax.xml.xpath.XPathFactory;
+
+import org.apache.log4j.Logger;
+import org.w3c.dom.Document;
+import org.w3c.dom.Node;
+import org.w3c.dom.NodeList;
+import org.xml.sax.SAXException;
+
+public class XmlHelper
+{
+	private final static Logger LOGGER = Logger.getLogger( XmlHelper.class );
+
+	// TODO check thread-safety
+	public static final XPath XPath = XPathFactory.newInstance().newXPath();
+	private static DocumentBuilder dBuilder;
+	static {
+		DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
+		dbFactory.setIgnoringComments( true );
+		try {
+			dBuilder = dbFactory.newDocumentBuilder();
+		} catch ( ParserConfigurationException e ) {
+			LOGGER.error( "Failed to initalize DOM parser with default configurations." );
+		}
+	}
+
+	public static Document parseDocumentFromStream( InputStream is )
+	{
+		Document doc = null;
+		try {
+			doc = dBuilder.parse( is );
+		} catch ( SAXException | IOException e ) {
+			LOGGER.error( "Failed to parse input stream to document." );
+		}
+		if ( doc == null )
+			return null;
+		doc.getDocumentElement().normalize();
+		return doc;
+	}
+
+	public static Document removeFormattingNodes( Document doc )
+	{
+		NodeList empty;
+		try {
+			empty = (NodeList)XPath.evaluate( "//text()[normalize-space(.) = '']",
+					doc, XPathConstants.NODESET );
+		} catch ( XPathExpressionException e ) {
+			LOGGER.error( "Bad XPath expression to find all empty text nodes." );
+			return null;
+		}
+
+		for ( int i = 0; i < empty.getLength(); i++ ) {
+			Node node = empty.item( i );
+			node.getParentNode().removeChild( node );
+		}
+		return doc;
+	}
+
+	public static String getUnformattedXml( InputStream is )
+	{
+		// prune empty text nodes, essentially removing all formatting
+		Document doc = parseDocumentFromStream( is );
+		return getXmlFromDocument( removeFormattingNodes( doc ), false );
+	}
+
+	public static String getFormattedXml( InputStream is )
+	{
+		Document doc = parseDocumentFromStream( is );
+		return getXmlFromDocument( doc, true );
+	}
+
+	public static String getXmlFromDocument( Document doc, boolean humanReadable )
+	{
+		try {
+			StringWriter writer = new StringWriter();
+			TransformerFactory tf = TransformerFactory.newInstance();
+			Transformer transformer = tf.newTransformer();
+			transformer.setOutputProperty( OutputKeys.OMIT_XML_DECLARATION, "no" );
+			transformer.setOutputProperty( OutputKeys.ENCODING, "UTF-8" );
+			transformer.setOutputProperty( OutputKeys.METHOD, "xml" );
+			if ( humanReadable ) {
+				transformer.setOutputProperty( OutputKeys.INDENT, "yes" );
+				transformer.setOutputProperty( "{http://xml.apache.org/xslt}indent-amount", "2" );
+			}
+			transformer.transform( new DOMSource( doc ), new StreamResult( writer ) );
+			return writer.toString();
+		} catch ( Exception ex ) {
+			LOGGER.error( "Failed to transform XML to String: ", ex );
+			return null;
+		}
+	}
+}
-- 
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