org.simpleframework.xml.filter.EnvironmentFilter Maven / Gradle / Ivy
/*
* EnvironmentFilter.java May 2006
*
* Copyright (C) 2006, Niall Gallagher
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General
* Public License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
* Boston, MA 02111-1307 USA
*/
package org.simpleframework.xml.filter;
/**
* The EnvironmentFilter object is used to provide a
* filter that will replace the specified values with an environment
* variable from the OS. This can be given a delegate filter which
* can be used to resolve replacements should the value requested
* not match an environment variable from the OS.
*
* @author Niall Gallagher
*/
public class EnvironmentFilter implements Filter {
/**
* Filter delegated to if no environment variable is resolved.
*/
private Filter filter;
/**
* Constructor for the EnvironmentFilter object. This
* creates a filter that resolves replacements using environment
* variables. Should the environment variables not contain the
* requested mapping this will return a null value.
*/
public EnvironmentFilter() {
this(null);
}
/**
* Constructor for the EnvironmentFilter object. This
* creates a filter that resolves replacements using environment
* variables. Should the environment variables not contain the
* requested mapping this will delegate to the specified filter.
*
* @param filter the filter delegated to should resolution fail
*/
public EnvironmentFilter(Filter filter) {
this.filter = filter;
}
/**
* Replaces the text provided with the value resolved from the
* environment variables. If the environment variables fail this
* will delegate to the specified Filter if it is
* not a null object. If no match is found a null is returned.
*
* @param text this is the text value to be replaced
*
* @return this will return the replacement text resolved
*/
public String replace(String text) {
String value = System.getenv(text);
if(value != null) {
return value;
}
if(filter != null) {
return filter.replace(text);
}
return null;
}
}