Add XML node to existing XML using JAVA code

Question

I have an existing XML ( JMeter JMX file). What is the best way / API's to implement the following use case in Java?

My goal is to insert the following XML (create new file):

<BackendListener guiclass="A" testclass="B" testname="C" enabled="true">
        <elementProp name="D" elementType="E" guiclass="F" testclass="G" enabled="true">
          <collectionProp name="H"/>
        </elementProp>
        <stringProp name="classname">I</stringProp>
</BackendListener>
<hashTree/>

Into the following existing XML file, where the work HERE is (under jmeterTestPlan-> hashTree -> hashTree -> last node)

<jmeterTestPlan version="A">
  <hashTree>
    <TestPlan guiclass="A" testclass="B" testname="C" enabled="true">

    </TestPlan>
    <hashTree>
      <ThreadGroup guiclass="D" testclass="E" testname="F" enabled="true">

      </ThreadGroup>
      <hashTree>
        <HTTPSamplerProxy guiclass="G" testclass="H" testname="I" enabled="true">
        </HTTPSamplerProxy>
        <hashTree/>
      </hashTree>

        ****HERE****

    </hashTree>
  </hashTree>
</jmeterTestPlan>

Any suggestion will be very appreciated!

Answer 1

Or the ugly, simplistic approach:

Read the file as a String:

File xmlFile = new File("jmeter.xml");
String xml;
try (Scanner scanner = new Scanner(xmlFile)) {
   xml= scanner.useDelimiter("\\A").next();
} 

Find the position:

int index = xml.indexOf("</HTTPSamplerProxy>");
index = xml.indexOf("</hashTree>", index);
index += "</hashTree>".length();

Insert the new part:

String newPart = "<BackendListener guiclass=\"A\" testclass=\"B\" testname=\"C\" enabled=\"true\">
        <elementProp name=\"D\" elementType=\"E\" guiclass=\"F\" testclass=\"G\" enabled=\"true\">
          <collectionProp name=\"H\"/>
        </elementProp>
        <stringProp name=\"classname\">I</stringProp>
</BackendListener>
<hashTree/>";
String newXML = xml.substring(0, index) + newPart + xml.substring(index)

Write the new XML String back to the file:

try (PrintWriter pw = new PrintWriter(xmlFile)) {
    pw.println(newXML);
}

Answer 2

There are lot of libraries in java which you can use to do manipulation on XML. Do have a look on the following:

You can use this parser if you want to parse large XML files and/or don't want to use a lot of memory.

http://download.oracle.com/javase/6/docs/api/javax/xml/parsers/SAXParserFactory.html

Example: http://www.mkyong.com/java/how-to-read-xml-file-in-java-sax-parser/

DOMParser

You can use this parser if you need to do XPath queries or need to have the complete DOM available.

http://download.oracle.com/javase/6/docs/api/javax/xml/parsers/DocumentBuilderFactory.html

Example: http://www.mkyong.com/java/how-to-read-xml-file-in-java-dom-parser/

Using this you can do marshaling of the XML get the instance add the new instance to the end and later unmarshaling to get the xml back

Answer 3

• Generate XSD from the XML using some free online tool ( http://xmlgrid.net/xml2xsd.html )
• Create JAXB classes from schema file ( http://www.javawebtutor.com/articles/jaxb/jaxb_java_class_from_xsd.php )

• Build the new object and serialize it using JAXB APIs

  JAXBContext jaxbContext = JAXBContext.newInstance(Customer.class); Marshaller jaxbMarshaller = jaxbContext.createMarshaller(); jaxbMarshaller.marshal(customer, System.out);

Answer 4

If you have an XSD file for this XML then you can easily generate Java classes from that using JAXB (for example with a Maven JAXB plugin) and unmarshal your XML file into a tree of object instances. Then you could programmatically add the instance you want and marshal the tree back into XML.