org.apache.juneau.svl.vars.SystemPropertiesVar Maven / Gradle / Ivy

Go to download
// ***************************************************************************************************************************
// * 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.                                              *
// ***************************************************************************************************************************
package org.apache.juneau.svl.vars;

import org.apache.juneau.svl.*;

/**
 * System property variable resolver.
 *
 * 
 * The format for this var is "$S{systemProperty[,defaultValue]}"
 *
 * 
Example:
 * 
 * 	// Create a variable resolver that resolves system properties (e.g. "$S{java.home}")
 * 	VarResolver varResolver = VarResolver.create().vars(SystemPropertiesVar.class).build();
 *
 * 	// Use it!
 * 	System.out.println(varResolver.resolve("java.home is set to $S{java.home}"));
 * 
 *
 * 
 * Since this is a {@link SimpleVar}, any variables contained in the result will be recursively resolved.
 * 
Likewise, if the arguments contain any variables, those will be resolved before they are passed to this var.
 *
 * 
See Also:

 * 	Simple Variable Language
 * 
 */
public class SystemPropertiesVar extends MapVar {

	/** The name of this variable. */
	public static final String NAME = "S";

	/**
	 * Constructor.
	 */
	public SystemPropertiesVar() {
		super(NAME, System.getProperties());
	}
}