net.segoia.scriptdao.core.VelocityCommandBuilder Maven / Gradle / Ivy

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Library to support dynamic command generation based on Apache Velocity templates
There is a newer version: 1.0.0
/**
 * script-dao - Library to support dynamic command generation based on Apache Velocity templates
 * Copyright (C) 2009  Adrian Cristian Ionescu - https://github.com/acionescu
 *
 * Licensed 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.
 */
package net.segoia.scriptdao.core;

import java.io.IOException;
import java.io.StringWriter;
import java.util.Map;

import org.apache.log4j.Logger;
import org.apache.velocity.app.VelocityEngine;
import org.apache.velocity.context.Context;
import org.apache.velocity.exception.MethodInvocationException;
import org.apache.velocity.exception.ParseErrorException;
import org.apache.velocity.exception.ResourceNotFoundException;
import org.apache.velocity.tools.Scope;
import org.apache.velocity.tools.ToolManager;
import org.apache.velocity.tools.config.EasyFactoryConfiguration;
import org.apache.velocity.tools.generic.DateTool;
import org.apache.velocity.tools.generic.DisplayTool;

public class VelocityCommandBuilder implements CommandBuilder {
	private static Logger logger = Logger.getLogger(VelocityCommandBuilder.class.getName());
	private static VelocityEngine velocityEngine;
	private static  ToolManager velocityToolManager;
	private String builderIdentifier = "VelocityCommandBuilder";
	static{

		velocityEngine = new VelocityEngine();
		
		EasyFactoryConfiguration toolboxConfig = new EasyFactoryConfiguration();
		toolboxConfig.toolbox(Scope.APPLICATION).tool(DisplayTool.class);
		toolboxConfig.toolbox(Scope.APPLICATION).tool(DateTool.class);
		
		velocityToolManager = new ToolManager(); 
		velocityToolManager.configure(toolboxConfig);
		
		try {
			velocityEngine.init();
			logger.info("Velocity Engine for Script Dao   successfully initialized");
		} catch (Exception e) {
			logger.error("Error initializing the velocity engine",e);
		}
	}
	

	public String buildCommand(String script, Map arguments) {
		StringWriter sw = new StringWriter();		
		Context vc = velocityToolManager.createContext();
		for(Object key : arguments.keySet()){
			vc.put(key.toString(),arguments.get(key));
		}
		
		try {
			//construct the command
			
			velocityEngine.evaluate(vc, sw, builderIdentifier, script);
		} catch (ParseErrorException e) {
			logger.error("Error merging the command '"+script+"' with context "+arguments,e);
		} catch (MethodInvocationException e) {
			logger.error("Error merging the command '"+script+"' with context "+arguments,e);
		} catch (ResourceNotFoundException e) {
			logger.error("Error merging the command '"+script+"' with context "+arguments,e);
		} catch (IOException e) {
			logger.error("Error merging the command '"+script+"' with context "+arguments,e);
		}		
		
		return sw.toString();
	}

}