XML parsing in Java via Groovy

Question

I\'m trying to parse an XML using Groovy and the ScriptEngine API of Java. The code below does exactly that but I wanted to know if there are any better ways of doing the sa

Answer 1

Your Groovy script could be "groovy-er"...

This does the same thing:

  String fact = "def getBookInformation(n) {" +
                "  xmlDesc = new XmlSlurper().parse(n)\n" +
                "  xmlDesc.book.findAll().collectEntries {\n"+
                "    [ (it.@id):[ it.name, it.author ] ]\n" +
                "  }\n" +
                "}" ; 

Indeed, you could use the GroovyShell rather than the JVM scripting engine, and that gets you down to:

import java.util.ArrayList;
import java.util.Map;
import groovy.lang.Binding ;
import groovy.lang.GroovyShell ;

public class XMLParsing {
  public static void main(String[] args) {
    Map<String, ArrayList<String>> resultMap = getBookDetails("test.xml");
    System.out.println(resultMap);
  }

  public static Map<String, ArrayList<String>> getBookDetails( String scriptXml ) {
    Binding b = new Binding() ;
    b.setVariable( "xmlFile", scriptXml ) ;
    GroovyShell shell = new GroovyShell( b ) ;
    Object ret = shell.evaluate( "new XmlSlurper().parse( xmlFile ).book.findAll().collectEntries { [ (it.@id):[ it.name, it.author ] ] }" ) ;
    return (Map<String, ArrayList<String>>)ret ;
  }
}

Answer 2

In order to make ScritpEngine more performant, we could use Compilable interface. The code below is a mix of novelty from Tim's comments and the discussion here.

public static Map<String, ArrayList<String>> getBookDetails(String scriptXml) {
    ScriptEngineManager factory = new ScriptEngineManager();
    ScriptEngine engine = factory.getEngineByName("groovy");
    engine.put("xmlFile", scriptXml);
    try {
        if (engine instanceof Compilable) {
            CompiledScript script = ((Compilable) engine).compile( "new XmlSlurper().parse( xmlFile ).book.findAll().collectEntries { [ (it.@id):[ it.name, it.author ] ] }" );         
            return (Map<String, ArrayList<String>>)(script.eval());
        }
    } catch (ScriptException e) {
        e.printStackTrace();
    } 
    return null;
}

Output:

{1=["Catcher In the Rye", J.D. Salinger], 2=["KiteRunner", Khaled Hosseini]}