environmentvariables.java

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/**
 * Copyright (c) 2003-2005 Craig Setera
 * All Rights Reserved.
 * Licensed under the Eclipse Public License - v 1.0
 * For more information see http://www.eclipse.org/legal/epl-v10.html
 */
package eclipseme.core.internal.utils;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Properties;

import org.eclipse.core.runtime.Platform;

/**
 * Wrapper around the environment variables queried from
 * the underlying operating system.
 * <p />
 * Copyright (c) 2003-2005 Craig Setera<br>
 * All Rights Reserved.<br>
 * Licensed under the Eclipse Public License - v 1.0<p/>
 * <br>
 * $Revision: 1.5 $
 * <br>
 * $Date: 2005/10/02 22:37:47 $
 * <br>
 * @author Craig Setera
 */

public class EnvironmentVariables {
	// The properties instance used to track the values
	private Properties variables;

	// The map of upper-cased property name to property name as found
	private Map nameMap;

	
	/**
	 * Construct a new instance.
	 * 
	 * @throws IOException
	 */
	public EnvironmentVariables() 
		throws IOException 
	{
		super();
		variables = new Properties();
		nameMap = new HashMap();
		retrieveEnvironmentVariables();
	}
	
	/**
	 * Return a boolean indicating whether or not the environment
	 * variables contains a variable of the specified name.
	 * 
	 * @param name
	 * @return
	 */
	public boolean containsVariable(String name) {
		return getVariable(name) != null;
	}
	
	/**
	 * Convert the environment variables into an array of Strings.
	 * 
	 * @return
	 */
	public String[] convertToStrings()
	{
		String[] strings = new String[variables.size()];
		
		int index = 0;
		Iterator entries = variables.entrySet().iterator();
		while (entries.hasNext()) {
			Map.Entry entry = (Map.Entry) entries.next();
			strings[index++] = entry.getKey() + "=" + entry.getValue();
		}
		
		return strings;
	}
	
	/**
	 * Return the variable value or <code>null</code> searching in
	 * a case-insensitive way.
	 * 
	 * @param name
	 * @return
	 */
	public String getVariable(String name) {
		// Handle things in a case insensitive manner...
		String caseSpecificName = (String) nameMap.get(name.toUpperCase());
		return (caseSpecificName == null) ? null : (String) variables.get(caseSpecificName);
	}
	
	/**
	 * Set the specified environment variable to the specified
	 * value.  This does not set the variable into the operating
	 * system, only into this holder class.
	 * 
	 * @param name
	 * @param value
	 */
	public void setVariable(String name, String value) {
		// Handle things in a case insensitive manner...
		String caseSpecificName = (String) nameMap.get(name.toUpperCase());
		if (caseSpecificName == null) {
			caseSpecificName = name;
			nameMap.put(caseSpecificName, caseSpecificName);
		}
		
		variables.setProperty(caseSpecificName, value);
	}
	
	/**
	 * Retrieve the environment variables.
	 * 
	 * @return
	 * @throws IOException
	 */
	private void retrieveEnvironmentVariables() 
		throws IOException 
	{
		// Launch a command to gather the environment variables
		String envVarsCommand = getEnvironmentVariablesCommand();
		Process process = Runtime.getRuntime().exec(envVarsCommand);
		InputStreamReader isr = new InputStreamReader(process.getInputStream());
		BufferedReader br = new BufferedReader(isr);

		// Parse the resulting properties
		String line = null;
		while ((line = br.readLine()) != null) {
			int equalsIndex = line.indexOf('=');
			if (equalsIndex != -1) {
				String key = line.substring(0, equalsIndex);
				String value = line.substring(equalsIndex + 1);
				variables.setProperty(key, value);
				nameMap.put(key.toUpperCase(), key);
			}
		}
	}
	
	/**
	 * Get the command to be executed to retrieve the enviroment
	 * variables.
	 * 
	 * @return
	 */
	private String getEnvironmentVariablesCommand() {
		String command = null;
		
		// NOTE: I'm assuming that we don't support Win95 or Win98 anymore...
//		if (os.indexOf("windows 9") > -1) {
//			command = "command.com /c set";
		
		if (Platform.getOS().equals(Platform.OS_WIN32)) {
			command = "cmd.exe /c set";
		} else {
		    command = "env";
		}
		
		return command;
	}
}