fixed - impl new XMLUtil class

Issue #212

open-bpmn.metamodel/src/main/java/org/openbpmn/bpmn/BPMNModel.java

@@ -44,6 +44,7 @@
 import org.openbpmn.bpmn.exceptions.BPMNInvalidTypeException;
 import org.openbpmn.bpmn.exceptions.BPMNMissingElementException;
 import org.openbpmn.bpmn.exceptions.BPMNModelException;
+import org.openbpmn.bpmn.util.BPMNXMLUtil;
 import org.w3c.dom.Document;
 import org.w3c.dom.Element;
 import org.w3c.dom.NamedNodeMap;
@@ -1687,9 +1688,13 @@ private void writeXml(Document doc, OutputStream output) throws TransformerExcep
         transformer.transform(source, dest);
         String xmlString = w.toString();
         // No indentation (whitespace) for elements with a CDATA section.
-        // See.
+        // See
         // https://stackoverflow.com/questions/55853220/handling-change-in-newlines-by-xml-transformation-for-cdata-from-java-8-to-java/75568933
-        xmlString = xmlString.replaceAll(">\\s*(<\\!\\[CDATA\\[(.|\\n|\\r\\n)*?]\\]>)\\s*</", ">$1</");
+        // xmlString =
+        // xmlString.replaceAll(">\\s*+(<\\!\\[CDATA\\[(.|\\n|\\r\\n)*?]\\]>)\\s*</",
+        // ">$1</");
+        xmlString = BPMNXMLUtil.cleanCDATAWhiteSpace(xmlString);
+
         // write output
         try {
             output.write(xmlString.getBytes(Charset.forName("UTF-8")));

open-bpmn.metamodel/src/main/java/org/openbpmn/bpmn/util/BPMNXMLUtil.java

@@ -0,0 +1,98 @@
+/********************************************************************************
+ * Copyright (c) 2022 Imixs Software Solutions GmbH and others.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0.
+ *
+ * This Source Code may also be made available under the following Secondary
+ * Licenses when the conditions for such availability set forth in the Eclipse
+ * Public License v. 2.0 are satisfied: GNU General Public License, version 2
+ * with the GNU Classpath Exception which is available at
+ * https://www.gnu.org/software/classpath/license.html.
+ *
+ * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
+ ********************************************************************************/
+package org.openbpmn.bpmn.util;
+
+/**
+ * The BPMNXMLUtil provides helper methods for xml strings
+ *
+ * @author rsoika
+ *
+ */
+public class BPMNXMLUtil {
+
+    /**
+     * This method removes whitespace around CDATA Tags like:
+     * 
+     * <imixs:value>
+     * <![CDATA[ some data ]]>
+     * </imixs:value>
+     * 
+     * results in:
+     * 
+     * <imixs:value><![CDATA[ some data ]]></imixs:value>
+     * 
+     * We can not use regex (replaceAll) here
+     * 
+     * xmlString =
+     * xmlString.replaceAll(">\\s*+(<\\!\\[CDATA\\[(.|\\n|\\r\\n)*?]\\]>)\\s*</",
+     * ">$1</");
+     * 
+     * 
+     * because of a known bug with large XML Strings. See
+     * https://stackoverflow.com/questions/7509905/java-lang-stackoverflowerror-while-using-a-regex-to-parse-big-strings
+     * 
+     * For this reason we parse and optimize the xml manually here.
+     *
+     * @param xml
+     * @return
+     */
+    public static String cleanCDATAWhiteSpace(String xml) {
+
+        boolean completed = false;
+        int lastPos = 0;
+        while (!completed) {
+            /**
+             * search for
+             * CDATA start '<![CDATA['
+             */
+            int pos = xml.indexOf("<![CDATA[", lastPos);
+            if (pos == -1) {
+                // no more CDATA !
+                completed = true;
+                break;
+            }
+            // find upper '>'
+            int backwardTagPos = xml.lastIndexOf(">", pos);
+            // do we have whitespace?
+            if (pos > backwardTagPos - 1) {
+                xml = xml.substring(0, backwardTagPos + 1) + xml.substring(pos);
+            }
+            lastPos = pos + 1;
+            /**
+             * next search for
+             * CDATA end ']]>'
+             */
+            pos = xml.indexOf("]]>", lastPos);
+            if (pos == -1) {
+                // wrong CDATA!
+                System.out.println("WRONG CDATA ELEMENT - unexpected end at: " + lastPos);
+                completed = true;
+                break;
+            }
+            pos = pos + 3;
+            // find upper '>'
+            int forwardTagPos = xml.indexOf("<", pos);
+            // do we have whitespace?
+            if (forwardTagPos > pos) {
+                xml = xml.substring(0, pos) + xml.substring(forwardTagPos);
+            }
+            lastPos = pos + 1;
+        }
+
+        return xml;
+    }
+
+}

open-bpmn.metamodel/src/test/java/org/openbpmn/output/TestCleanCDATA.java

@@ -0,0 +1,22 @@
+package org.openbpmn.output;
+
+import org.junit.jupiter.api.Test;
+import org.openbpmn.bpmn.util.BPMNXMLUtil;
+
+/**
+ * Test Class to test clean up of cdata whitespace
+ */
+public class TestCleanCDATA {
+
+    @Test
+    public void testSimple() {
+
+        String xml = "<imixs:value>   \n  <![CDATA[ some data ]]>\n   </imixs:value>";
+
+        System.out.println(xml);
+        String result = BPMNXMLUtil.cleanCDATAWhiteSpace(xml);
+
+        System.out.println(result);
+
+    }
+}