Lucene example source code file (QueryTemplateManager.java)

This example Lucene source code file (QueryTemplateManager.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Lucene tags/keywords

document, dom, domresult, domsource, inputstream, io, ioexception, ioexception, parser, parserconfigurationexception, parserconfigurationexception, sax, saxexception, saxexception, string, templates, transformerexception, transformerexception, util, xml

The Lucene QueryTemplateManager.java source code

package org.apache.lucene.xmlparser;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Properties;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.Result;
import javax.xml.transform.Templates;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMResult;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.xml.sax.SAXException;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/**
 * Provides utilities for turning query form input (such as from a web page or Swing gui) into 
 * Lucene XML queries by using XSL templates.  This approach offers a convenient way of externalizing 
 * and changing how user input is turned into Lucene queries. 
 * Database applications often adopt similar practices by externalizing SQL in template files that can
 * be easily changed/optimized by a DBA.  
 * The static methods can be used on their own or by creating an instance of this class you can store and 
 * re-use compiled stylesheets for fast use (e.g. in a server environment)
 */
public class QueryTemplateManager
{
	static DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance ();
	static TransformerFactory tFactory = TransformerFactory.newInstance();

	HashMap<String,Templates> compiledTemplatesCache=new HashMap();
	Templates defaultCompiledTemplates=null;

	
	public QueryTemplateManager()
	{
		
	}
	public QueryTemplateManager(InputStream xslIs) throws TransformerConfigurationException, ParserConfigurationException, SAXException, IOException
	{
		addDefaultQueryTemplate(xslIs);
	}
	public void addDefaultQueryTemplate(InputStream xslIs) throws TransformerConfigurationException, ParserConfigurationException, SAXException, IOException
	{
		defaultCompiledTemplates=getTemplates(xslIs);
	}
	public void addQueryTemplate(String name, InputStream xslIs) throws TransformerConfigurationException, ParserConfigurationException, SAXException, IOException
	{
		compiledTemplatesCache.put(name,getTemplates(xslIs));
	}
	public String getQueryAsXmlString(Properties formProperties,String queryTemplateName) throws SAXException, IOException, ParserConfigurationException, TransformerException
	{
		Templates ts= compiledTemplatesCache.get(queryTemplateName);
		return getQueryAsXmlString(formProperties, ts);
	}
	
	public Document getQueryAsDOM(Properties formProperties,String queryTemplateName) throws SAXException, IOException, ParserConfigurationException, TransformerException
	{
		Templates ts= compiledTemplatesCache.get(queryTemplateName);
		return getQueryAsDOM(formProperties, ts);
	}
	public String getQueryAsXmlString(Properties formProperties) throws SAXException, IOException, ParserConfigurationException, TransformerException
	{
		return getQueryAsXmlString(formProperties, defaultCompiledTemplates);
	}
	
	public Document getQueryAsDOM(Properties formProperties) throws SAXException, IOException, ParserConfigurationException, TransformerException
	{
		return getQueryAsDOM(formProperties, defaultCompiledTemplates);
	}
	
	
	/**
	 * Fast means of constructing query using a precompiled stylesheet  
	 */		
	public static String getQueryAsXmlString(Properties formProperties, Templates template) throws SAXException, IOException, ParserConfigurationException, TransformerException 
	{
  		ByteArrayOutputStream baos=new ByteArrayOutputStream();
  		StreamResult result=new StreamResult(baos);
  		transformCriteria(formProperties,template,result);
  		return baos.toString();  		
	}
	
	/**
	 * Slow means of constructing query parsing a stylesheet from an input stream  
	 */		
	public static String getQueryAsXmlString(Properties formProperties, InputStream xslIs) throws SAXException, IOException, ParserConfigurationException, TransformerException 
	{
  		ByteArrayOutputStream baos=new ByteArrayOutputStream();
  		StreamResult result=new StreamResult(baos);
  		transformCriteria(formProperties,xslIs,result);
  		return baos.toString();  		
	}
			

	/**
	 * Fast means of constructing query using a cached,precompiled stylesheet  
	 */	
	public static Document getQueryAsDOM(Properties formProperties, Templates template) throws SAXException, IOException, ParserConfigurationException, TransformerException
	{
  		DOMResult result=new DOMResult();
  		transformCriteria(formProperties,template,result);
  		return (Document)result.getNode();
	}

	
	/**
	 * Slow means of constructing query - parses stylesheet from input stream 
	 */
	public static Document getQueryAsDOM(Properties formProperties, InputStream xslIs) throws SAXException, IOException, ParserConfigurationException, TransformerException
	{
  		DOMResult result=new DOMResult();
  		transformCriteria(formProperties,xslIs,result);
  		return (Document)result.getNode();
	}
	
	
	
	
	/**
	 * Slower transformation using an uncompiled stylesheet (suitable for development environment)
	 */
	public static void transformCriteria(Properties formProperties, InputStream xslIs, Result result) throws SAXException, IOException, ParserConfigurationException, TransformerException
	{
        dbf.setNamespaceAware(true);	    
		DocumentBuilder builder = dbf.newDocumentBuilder();
		org.w3c.dom.Document xslDoc = builder.parse(xslIs);
		DOMSource ds = new DOMSource(xslDoc);
		
		Transformer transformer =null;
		synchronized (tFactory)
		{
			transformer = tFactory.newTransformer(ds);			
		}
		transformCriteria(formProperties,transformer,result);
	}
	
	/**
	 * Fast transformation using a pre-compiled stylesheet (suitable for production environments)
	 */
	public static void transformCriteria(Properties formProperties, Templates template, Result result) throws SAXException, IOException, ParserConfigurationException, TransformerException
	{
		transformCriteria(formProperties,template.newTransformer(),result);
	}
	
	
	
	public static void transformCriteria(Properties formProperties, Transformer transformer, Result result) throws SAXException, IOException, ParserConfigurationException, TransformerException
	{
        dbf.setNamespaceAware(true);
        
	    //Create an XML document representing the search index document.
		DocumentBuilder db = dbf.newDocumentBuilder ();
		org.w3c.dom.Document doc = db.newDocument ();
		Element root = doc.createElement ("Document");
		doc.appendChild (root);
		
		Enumeration keysEnum = formProperties.keys();
		while(keysEnum.hasMoreElements())
		{
		    String propName=(String) keysEnum.nextElement();
		    String value=formProperties.getProperty(propName);
    		if((value!=null)&&(value.length()>0))
    		{
    		    DOMUtils.insertChild(root,propName,value);    			
    		}
		}		
		//Use XSLT to to transform into an XML query string using the  queryTemplate
		DOMSource xml=new DOMSource(doc);
		transformer.transform(xml,result);		
	}
	
	/**
	 * Parses a query stylesheet for repeated use
	 */
	public static Templates getTemplates(InputStream xslIs) throws ParserConfigurationException, SAXException, IOException, TransformerConfigurationException  
	{
        dbf.setNamespaceAware(true);	    
		DocumentBuilder builder = dbf.newDocumentBuilder();
		org.w3c.dom.Document xslDoc = builder.parse(xslIs);
		DOMSource ds = new DOMSource(xslDoc);
		return tFactory.newTemplates(ds);
	}
}