Append node to an existing xml-Java

Question

I have seen the same question being answered for vb and c#, but i need a Java best solution for appending nodes to an xml. Will xpath help? I have

<A>
  <B>
    <c>1<c/>
    <d>2<d/>
    <e>3<e/>
  </B>
  <B>
    <c>1<c/>
    <d>2<d/>
    <e>3<e/>
  </B>
</A>

Need to append another

<B>
   <c>11<c/>
   <d>21<d/>
   <e>31<e/>
</B>

Answer 1

XPath will help you to find nodes, but not really append them. I don't think you'd find it particularly useful here.

Which XML API are you using? If it's the W3C DOM (urgh) then you'd do something like:

Element newB = document.createElement("B");
Element newC = document.createElement("c");
newC.setTextContent("11");
Element newD = document.createElement("d");
newD.setTextContent("21");
Element newE = document.createElement("e");
newE.setTextContent("31");
newB.appendChild(newC);
newB.appendChild(newD);
newB.appendChild(newE);
document.getDocumentElement().appendChild(newB);

Answer 2

The most strait-forward way is that you parse, using Sax or Dom, all the files into a data structure, for example an A class which has a B class with members of C,D,E class in your case.

And output the data structure back to XML.

Answer 3

You may want to use XMLModier of vtd-xml to do it in a cool way, which is to append the byte content directly... You just need to call XMLModier's insertAfterElement()... below is a link to the code sample: Incrementally Modify XML in Java:

import com.ximpleware.*;
import java.io.*;

public class ModifyXML {
     public static void main(String[] s) throws Exception{
        VTDGen vg = new VTDGen(); // Instantiate VTDGen
        XMLModifier xm = new XMLModifier(); //Instantiate XMLModifier
        if (vg.parseFile("old.xml",false)){
             VTDNav vn = vg.getNav();
             xm.bind(vn);

             // first update the value of attr
             int i = vn.getAttrVal("attr");
             if (i!=-1){
                  xm.updateToken(i,"value");
             }

             // navigate to <a>
            if (vn.toElement(VTDNav.FC,"a")) {
                  // update the text content of <a>
                   i=vn.getText();
                   if (i!=-1){
                      xm.updateToken(i," new content ");
                   }
                   // insert an element before <a> (which is the cursor element)
                   xm.insertBeforeElement("<b/>\n\t");

                   // insert an element after <a> (which is the cursor element)
                   xm.insertAfterElement("\n\t<c/>");
            }

            xm.output(new FileOutputStream("new.xml"));
         }
     }

}