Logback: the reliable, generic, fast and flexible logging framework.
Copyright (C) 1999-2015, QOS.ch. All rights reserved.
This program and the accompanying materials are dual-licensed under
either the terms of the Eclipse Public License v1.0 as published by
the Eclipse Foundation
  or (per the licensee's choosing)
under the terms of the GNU Lesser General Public License version 2.1
as published by the Free Software Foundation.
/**
 * Logback: the reliable, generic, fast and flexible logging framework.
 * Copyright (C) 1999-2015, QOS.ch. All rights reserved.
 *
 * This program and the accompanying materials are dual-licensed under
 * either the terms of the Eclipse Public License v1.0 as published by
 * the Eclipse Foundation
 *
 *   or (per the licensee's choosing)
 *
 * under the terms of the GNU Lesser General Public License version 2.1
 * as published by the Free Software Foundation.
 */
package ch.qos.logback.core.property;

import ch.qos.logback.core.PropertyDefinerBase;
import ch.qos.logback.core.util.Loader;
import ch.qos.logback.core.util.OptionHelper;

import java.net.URL;

In conjunction with PropertyAction sets the named variable to "true" if the resource specified by the user is available on the class path, "false" otherwise. 
Author:
XuHuisheng, Ceki Gulcu
See Also:
getPropertyValue()
Since:
1.1.0/**
 * In conjunction with {@link ch.qos.logback.core.joran.action.PropertyAction} sets
 * the named variable to "true" if the {@link #setResource(String) resource} specified
 * by the user is available on the class path, "false" otherwise.
 *
 * @see #getPropertyValue()
 *
 * @author XuHuisheng
 * @author Ceki Gulcu
 * @since 1.1.0
 */
public class ResourceExistsPropertyDefiner extends PropertyDefinerBase {

    String resourceStr;

    public String getResource() {
        return resourceStr;
    }

    
The resource to search for on the class path.
Params:
resource – /**
     * The resource to search for on the class path.
     *
     * @param resource
     */
    public void setResource(String resource) {
        this.resourceStr = resource;
    }

    
Returns the string "true" if the resource specified by the user is available on the class path, "false" otherwise. 
Returns:
"true"|"false" depending on the availability of resource on the classpath/**
     * Returns the string "true" if the {@link #setResource(String) resource} specified by the
     * user is available on the class path, "false" otherwise.
     *
     * @return "true"|"false" depending on the availability of resource on the classpath
     */
    public String getPropertyValue() {
        if (OptionHelper.isEmpty(resourceStr)) {
            addError("The \"resource\" property must be set.");
            return null;
        }

        URL resourceURL = Loader.getResourceBySelfClassLoader(resourceStr);
        return booleanAsStr(resourceURL != null);
    }

}