Develop Reference

How to avoid extra blank lines in XML generation with Java?

Currently I'm trying to develop some code with Java 9 and javax.xml libraries (both mandatory for my task) that edits an XML file and I'm having some weird issues adding child nodes.
This is the XML file:
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<users>
</users>
and I want to edit it build something like this:
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<users>
<user>
<name>A name</name>
<last-name>Last Name</last-name>
<username>username</username>
</user>
</users>
Now, the first run of the code adds a single blank line before the <user> node. When it runs for a second time fills with more blank lines:
<users>
<user>
<name>name</name>
<last-name>lastname</last-name>
<username>username</username>
</user>
<user>
<name>name</name>
<last-name>lastname</last-name>
<username>username</username>
</user>
</users>
This is the XML generated after running the program 2 times. As you can see, it adds blank lines before the <user> nodes and between the other nodes, exactly n-1 blank lines between nodes being n the times the code was executed.
Wondering what is the content of those nodes before updating the file I wrote the next code:
int i=0;
while (root.getChildNodes().item(i)!=null){
Node aux = root.getChildNodes().item(i);
System.out.println("Node text content: ".concat(aux.getTextContent()));
i++;
}
1st execution:
Node text content:
Node text content: namelastnameusername
2nd execution:
Node text content:
Node text content:
name
lastname
username
Node text content:
Node text content: namelastnameusername
3rd execution
Node text content:
Node text content:
name
lastname
username
Node text content:
Node text content:
name
lastname
username
Node text content:
Node text content: namelastnameusername
Finally, this is the Java code:
private static void saveUser(String firstName, String lastName, String username){
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
try {
DocumentBuilder builder = factory.newDocumentBuilder();
Document doc = builder.parse(new File(databaseFile));
Element root = doc.getDocumentElement();
root.normalize();
// build user node
Element userNode = doc.createElement("user");
Element nameNode = doc.createElement("name");
Element lastNameNode = doc.createElement("last-name");
Element usernameNode = doc.createElement("username");
//build structure
nameNode.appendChild(doc.createTextNode(firstName));
lastNameNode.appendChild(doc.createTextNode(lastName));
usernameNode.appendChild(doc.createTextNode(username));
userNode.appendChild(nameNode);
userNode.appendChild(lastNameNode);
userNode.appendChild(usernameNode);
root.appendChild(userNode);
//write the updated document to file or console
TransformerFactory transformerFactory = TransformerFactory.newInstance();
Transformer transformer = transformerFactory.newTransformer();
DOMSource source = new DOMSource(doc);
StreamResult result = new StreamResult(new File(databaseFile));
transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.transform(source, result);
}catch (SAXException | ParserConfigurationException | IOException | TransformerException e1) {
e1.printStackTrace();
}
}
The only solution I could find is to delete blank lines after XML generation, but I think it's not a proper solution and I would like to find some alternatives first.
Any suggestions on how to tackle this problem?

I suspect it's the Transformer that's adding the blank lines.
Instead of using the default transformer (transformerFactory.newTransformer()), try passing in an XSLT that has xsl:strip-space set (transformerFactory.newTransformer(new StreamSource(new File(PATH_TO_XSLT_FILE)));)...
XSLT File
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output indent="yes"/>
<xsl:strip-space elements="*"/>
<xsl:template match="#*|node()">
<xsl:copy>
<xsl:apply-templates select="#*|node()"/>
</xsl:copy>
</xsl:template>
</xsl:stylesheet>

In Short： Actually, in Java 9, you may only take the way of deleting the blank line after xml generated or after xml parsed from file, like :
private void clearBlankLine(Element element) {
NodeList childNodes = element.getChildNodes();
for (int index = 0; index < childNodes.getLength(); index++) {
Node item = childNodes.item(index);
if (item.getNodeType() != 1 && System.lineSeparator()
.equals(item.getNodeValue())) {
element.removeChild(item);
} else {
if (item instanceof Element) {
clearBlankLine((Element) item);
}
}
}
}
Then invoke this with root element.
Details:
In the flow of xml generation, there are three lifecycle for each element parse: startElement,parse,endElement. While the indent feature is implemented in the startElement scope. Also the indent will add a blank line in document.
The invoke stack is different in java 8 between java 9:
In Java 8: ToStream#startElement-> ToStream#indent(IfNecessary)
In Java 9: ToStream#startElement->ToStream#flushCharactersBuffer(IfNecessary)->ToStream#indent(IfNecessary)
While the flushCharactersBuffer also do indent when we open the indent feature like: transformer.setOutputProperty(OutputKeys.INDENT, "yes"); Also the condition to invoke method: flushCharactersBuffer and method: indent almost same.
That means in Java 9, this would add two new line for each need indented element, result to blank lines appeared.

I found this solution using an XPath to be much cleaner than any of the others here (h/t to Isaac for his answer over at https://stackoverflow.com/a/12670194/1339923). It doesn't require a separate (i.e., XSLT) file, and doesn't require you to add 14 lines of Java to iterate over every node in the Document. Only 6 lines of code.
In the case of #pablo-r-grande's original question... right before this comment (i.e., just before loading the Document into the DOMSource):
//write the updated document to file or console
...I would add these lines:
// Generate list of all empty Nodes, them remove them
XPath xp = XPathFactory.newInstance().newXPath();
NodeList nl = (NodeList) xp.evaluate("//text()[normalize-space(.)='']", doc, XPathConstants.NODESET);
for (int i = 0; i < nl.getLength(); ++i) { // note the position of the '++'
Node node = nl.item(i);
node.getParentNode().removeChild(node);
}

your solution and below suggestion are both works fine for me, please try with this test case,
public static void main(String[] args) {
saveUser("test one", "test two", "test three");
}
private static void saveUser(String firstName, String lastName, String username){
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
try {
DocumentBuilder builder = factory.newDocumentBuilder();
Document doc = builder.parse(new File("second.xml"));
Element root = doc.getDocumentElement();
root.normalize();
// build user node
Element userNode = doc.createElement("user");
Element nameNode = doc.createElement("name");
Element lastNameNode = doc.createElement("last-name");
Element usernameNode = doc.createElement("username");
userNode.appendChild(nameNode).setTextContent(firstName); //set the text content
userNode.appendChild(lastNameNode).setTextContent(lastName);
userNode.appendChild(usernameNode).setTextContent(username);
root.appendChild(userNode);
//write the updated document to file or console
TransformerFactory transformerFactory = TransformerFactory.newInstance();
Transformer transformer = transformerFactory.newTransformer();
DOMSource source = new DOMSource(doc);
StreamResult result = new StreamResult(new File("second.xml"));
transformer.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
transformer.setOutputProperty(OutputKeys.INDENT, "yes");
transformer.transform(source, result);
}catch (Exception e) {
e.printStackTrace();
}
}
second.xml (before execution)
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<users>
</users>
second.xml (first execution)
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<users>
<user>
<name>test one</name>
<last-name>test two</last-name>
<username>test three</username>
</user>
</users>
second.xml (second execution)
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<users>
<user>
<name>test one</name>
<last-name>test two</last-name>
<username>test three</username>
</user>
<user>
<name>test one</name>
<last-name>test two</last-name>
<username>test three</username>
</user>
</users>
second.xml (third execution)
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<users>
<user>
<name>test one</name>
<last-name>test two</last-name>
<username>test three</username>
</user>
<user>
<name>test one</name>
<last-name>test two</last-name>
<username>test three</username>
</user>
<user>
<name>test one</name>
<last-name>test two</last-name>
<username>test three</username>
</user>
</users>
importing classes,
import java.io.File;
import javax.xml.parsers.DocumentBuilderFactory;
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.parsers.DocumentBuilder; // missing import class
import org.w3c.dom.Document;
import org.w3c.dom.Element;

Xml Output generation from excel sheet

I am trying to convert an excel file into xml file in java.
try {
DocumentBuilderFactory dFact = DocumentBuilderFactory.newInstance();
DocumentBuilder build = dFact.newDocumentBuilder();
Document doc = build.newDocument();
Element root = doc.createElement("dataroot");
doc.appendChild(root);
Element Details = doc.createElement("DATA");
root.appendChild(Details);
for(int i=0; i<list.size()-2; i +=3 ) {
Element name = doc.createElement("Name");
name.appendChild(doc.createTextNode(String.valueOf(list.get(i))));
Details.appendChild(name);
Element id = doc.createElement("Empid");
id.appendChild(doc.createTextNode(String.valueOf(list.get(i+1))));
Details.appendChild(id);
Element ad = doc.createElement("Add");
ad.appendChild(doc.createTextNode(String.valueOf(list.get(i+2))));
Details.appendChild(ad);
Element mo = doc.createElement("Mobile");
mo.appendChild(doc.createTextNode(String.valueOf(list.get(i+3))));
Details.appendChild(mo);
}
// Save the document to the disk file
TransformerFactory tranFactory = TransformerFactory.newInstance();
Transformer aTransformer = tranFactory.newTransformer();
// format the XML nicely
aTransformer.setOutputProperty(OutputKeys.ENCODING, "ISO-8859-1");
aTransformer.setOutputProperty(
"{http://xml.apache.org/xslt}indent-amount", "4");
aTransformer.setOutputProperty(OutputKeys.INDENT, "yes");
This is my code for reading an ArrayList of excel data (with values and null) and convert it into xml.
my output is:
<?xml version="1.0" encoding="ISO-8859-1" standalone="no"?>
<dataroot generated="2015-04-26T10:52:27">
<DATA>
<Name>Rony</Name>
<Empid>FBL123</Empid>
<Add>Dhaka</Add>
<Mobile>12333333</Mobile>
</DATA>
<DATA>
<Name>12333333</Name>
<Empid>Azam</Empid>
<Add>FBL321</Add>
<Mobile>Dhaka</Mobile>
</DATA>
<DATA>
<Name>Dhaka</Name>
<Empid>67778888</Empid>
<Add>Rony</Add>
<Mobile>Chandpur</Mobile>
</DATA>
<DATA>
<Name>Chandpur</Name>
<Empid>099776655</Empid>
<Add>Azam</Add>
<Mobile>9988</Mobile>
</DATA>
</dataroot>
But my desired xml output is:
<?xml version="1.0" encoding="UTF-8"?>
<dataroot xmlns:od="urn:schemas-microsoft-com:officedata" generated="2015-04-26T10:52:27">
<DATA>
<Name>Rony</Name>
<Empid>FBL123</Empid>
<Add>Dhaka</Add>
<Mobile><Prop ID="Personal" ValStr="Mrs. YYYYYYYY " /><Prop ID="FAMILY" ValStr="Mrs. ZZZZZZZZ" />"</CLIENTPROP>
</DATA>
<DATA>
<Name>AZAM</Name>
<Empid>FBL321</Empid>
<Add>Dhaka</Add>
<Mobile><Prop ID="Personal" ValStr="Mrs. YYYYYYYY " /><Prop ID="FAMILY" ValStr="Mrs. ZZZZZZZZ" />"</CLIENTPROP>
</DATA>
</dataroot>
How i Can do it?

To have "DATA" tags, you shoud move the lines below into your for statement:
Element Details = doc.createElement("DATA");
root.appendChild(Details);
To add some property on "dataroot", use the code below:
root.setAttribute("generated", "2015-04-26T10:52:27");
On Mobile element, try this:
Element mo = doc.createElement("Mobile");
Element prop = doc.createElement("Prop");
prop.setAttribute("ID", "FAMILY");
prop.setAttribute("ValStr", "Mrs. YYYYYYYY");
Element prop2 = doc.createElement("Prop");
prop2.setAttribute("ID", "Personal");
prop2.setAttribute("ValStr", "Mrs. ZZZZZZZZ");
mo.appendChild(prop);
mo.appendChild(prop2);
Try to read about DOM parser on this tutorial as well. How to create XML file in Java – (DOM Parser)

XML Namespace - xmlns

I'm trying to generate a XML from Java.
Something like this:
<?xml version="1.0" encoding="UTF-8"?>
<ElementFile
xmlns="http://www.url.com/bla/bla"
xmlns:common="http://www.url.com/bla/bla/bla">
<Regulation>
<blablaElement>0000-0000</blablaElement>
</Regulation>
</ElementFile>
To do this, I wrote the following code:
ElementFile = document.addElement( "ElementFile" )
.addNamespace("xmlns","http://www.url.com/bla/bla")
.addNamespace("common", "http://www.url.com/bla/bla/bla");
But the generated code is:
<?xml version="1.0" encoding="UTF-8"?>
<ElementFile
xmlns:xmlns="http://www.url.com/bla/bla"
xmlns:common="http://www.url.com/bla/bla/bla">
<Regulation>
<blablaElement>0000-0000</blablaElement>
</Regulation>
</ElementFile>
However, if I write this (without xmlns)
ElementFile = document.addElement( "ElementFile" )
.addNamespace("","http://www.url.com/bla/bla")
.addNamespace("common", "http://www.url.com/bla/bla/bla");
Then, the xml generates the line properly but it adds xmlns=" " by default:
<?xml version="1.0" encoding="UTF-8"?>
<ElementFile
xmlns="http://www.url.com/bla/bla"
xmlns:common="http://www.url.com/bla/bla/bla">
<Regulation xmlns="">
<blablaElement>0000-0000</blablaElement>
</Regulation>
</ElementFile>
I'm quite lost...
[UPDATED QUESTION]
I'm sorry, but I don't understand how to integrated your answer in my code. I am new to this domain.
My complete code is:
XMLWriter writer = new XMLWriter(new FileWriter("xmlFileName"), format);
Document document = DocumentHelper.createDocument();
Element ElementFile = document.addElement( "ElementFile" )
.addNamespace("xmlns","http://www.url.com/bla/bla")
.addNamespace("xmlns:common", "http://www.url.com/bla/bla/bla");
Element Regulation = ElementFile.addElement( "Regulation" );
Element blablaElement = Regulation.addElement( "blablaElement" )
.addText( "0000-0000" );
writer.write(document);
writer.close();

DocumentBuilderFactory dbfac = DocumentBuilderFactory.newInstance();
dbfac.setNamespaceAware(true);
DocumentBuilder docBuilder;
docBuilder = dbfac.newDocumentBuilder();
DOMImplementation domImpl = docBuilder.getDOMImplementation();
Document doc = domImpl.createDocument("http://www.url.com/bla/bla", "ElementFile ", null);
doc.setXmlVersion("1.0");
doc.setXmlStandalone(true);
Element elementFile = doc.getDocumentElement();
elementFile.setAttributeNS("http://www.w3.org/2000/xmlns/","xmlns:common","http://www.url.com/bla/bla/bla");
and add elements to this doc
you have a similar question here: How to create attribute (xmlns:xsd) to XML node in Java?

Correct namespace declaration in Java

I need to create an XML document with the following structure:
<?xml version="1.0" ?>
<Cancelacion xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
RfcEmisor="VSI850514HX4"
Fecha="2011-11-23T17:25:06"
xmlns="http://cancelacfd.sat.gob.mx">
<Folios>
<UUID>BD6CA3B1-E565-4985-88A9-694A6DD48448</UUID>
</Folios>
</Cancelacion>
The structure MUST be that way. But I'm not very familiar with the namespace declaration for the XML Elements. I can correctly generate an XML with the following structure:
<?xml version="1.0" ?>
<Cancelacion RfcEmisor="VSI850514HX4"
Fecha="2011-11-23T17:25:06"
xmlns="http://cancelacfd.sat.gob.mx">
<Folios>
<UUID>BD6CA3B1-E565-4985-88A9-694A6DD48448</UUID>
</Folios>
</Cancelacion>
But the problem is that I can't get to include the xmls:xsd and xmlns:xsi correctly. The code for properly generating the previously mentioned code is:
// Crear un document XML vacío
DocumentBuilderFactory dbfac = DocumentBuilderFactory.newInstance();
dbfac.setNamespaceAware(true);
DocumentBuilder docBuilder;
docBuilder = dbfac.newDocumentBuilder();
Document doc = docBuilder.newDocument();
doc.setXmlVersion("1.0");
doc.setXmlStandalone(true);
Element cancelacion = doc.createElementNS("http://cancelacfd.sat.gob.mx","Cancelacion");
cancelacion.setAttribute("RfcEmisor", rfc);
cancelacion.setAttribute("Fecha", fecha);
doc.appendChild(cancelacion);
Element folios = doc.createElementNS("http://cancelacfd.sat.gob.mx", "Folios");
cancelacion.appendChild(folios);
for (int i=0; i<uuid.length; i++) {
Element u = doc.createElementNS("http://cancelacfd.sat.gob.mx","UUID");
u.setTextContent(uuid[i]);
folios.appendChild(u);
}

You can add additional namespaces by calling setAttributeNS method on the root element
as shown in below example
// get the root element
Element rootElement = xmlDoc.getDocumentElement();
// add additional namespace to the root element
rootElement.setAttributeNS("http://www.w3.org/2000/xmlns/", "xmlns:xsd", "http://www.w3.org/2001/XMLSchema");
You can then add elements to a given namespace by using the method like below
// append author element to the document element
Element author = xmlDoc.createElement("xsd:element");
Read this article for more details.

Selecting xml raw text

Given xml like this:
<container>
<item>
<xmlText>
<someTag>
<otherTag>
Text
</otherTag>
</someTag>
</xmlText>
</item>
<container>
I would like to select all text that is under item/xmlText. I would like to print all the content of this node with tags (someTag, otherTag).
I would prefer to handle with this with XPath, but this is part of Java program, so if there is such mechanism I could take it as well.

Use XSLT for this:
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output omit-xml-declaration="yes" indent="yes"/>
<xsl:strip-space elements="*"/>
<xsl:template match="/">
<xsl:copy-of select="/container/item/xmlText/node()"/>
</xsl:template>
</xsl:stylesheet>
When this is applied on the provided XML document (corrected to be well-formed !!!):
<container>
<item>
<xmlText>
<someTag>
<otherTag>
Text
</otherTag>
</someTag>
</xmlText>
</item>
</container>
the wanted, correct result is produced:
<someTag>
<otherTag>
Text
</otherTag>
</someTag>

When this is your Element retrieved with XPath
XPathFactory factory = XPathFactory.newInstance();
XPath xpath = factory.newXPath();
Element element = (Element) xpath.evaluate(
"/container/item/xmlText", document, XPathConstants.NODE);
Then, you can do something along these lines:
java.io.ByteArrayOutputStream data =
new java.io.ByteArrayOutputStream();
java.io.PrintStream ps = new java.io.PrintStream(data);
// These classes are part of Xerces. But you will find them in your JDK,
// as well, in a different package. Use any encoding here:
org.apache.xml.serialize.OutputFormat of =
new org.apache.xml.serialize.OutputFormat("XML", "ISO-8859-1", true);
org.apache.xml.serialize.XMLSerializer serializer =
new org.apache.xml.serialize.XMLSerializer(ps, of);
// Here, serialize the element that you obtained using your XPath expression.
serializer.asDOMSerializer();
serializer.serialize(element);
// The output stream now holds serialized XML data, including tags/attributes...
return data.toString();
UPDATE
This would be more concise, rather than using Xerces internals. It's the same as Dimitre's solution, just not with an XSLT stylesheet but all in Java:
ByteArrayOutputStream out = new ByteArrayOutputStream();
Transformer transformer = TransformerFactory.newInstance().newTransformer();
transformer.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
Source source = new DOMSource(element);
Result target = new StreamResult(out);
transformer.transform(source, target);
return out.toString();