Use the feature "LS" or "LS-Async" to find a  
DOMImplementation object that supports
Load and Save.
Cast the DOMImplementation object to
DOMImplementationLS.
System.setProperty(DOMImplementationRegistry.PROPERTY,
  "org.apache.xerces.dom.DOMImplementationSourceImpl");
DOMImplementationRegistry registry = DOMImplementationRegistry.newInstance();
DOMImplementation impl = registry.getDOMImplementation("XML 1.0 LS 3.0");
  if (impl != null) {
    DOMImplementationLS implls = (DOMImplementationLS) impl;
    // ...
  }