Author: oheger Date: Sun Sep 22 17:46:34 2013 New Revision: 1525394 URL: http://svn.apache.org/r1525394 Log: Added FileLocationStrategy interface.
This interface will be used for making the process of resolving files customizable. Added: commons/proper/configuration/trunk/src/main/java/org/apache/commons/configuration/io/FileLocationStrategy.java Added: commons/proper/configuration/trunk/src/main/java/org/apache/commons/configuration/io/FileLocationStrategy.java URL: http://svn.apache.org/viewvc/commons/proper/configuration/trunk/src/main/java/org/apache/commons/configuration/io/FileLocationStrategy.java?rev=1525394&view=auto ============================================================================== --- commons/proper/configuration/trunk/src/main/java/org/apache/commons/configuration/io/FileLocationStrategy.java (added) +++ commons/proper/configuration/trunk/src/main/java/org/apache/commons/configuration/io/FileLocationStrategy.java Sun Sep 22 17:46:34 2013 @@ -0,0 +1,69 @@ +/* + * 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.commons.configuration.io; + +import java.net.URL; + +/** + * <p> + * An interface allowing applications to customize the process of locating a + * file. + * </p> + * <p> + * {@link FileHandler} uses {@link FileLocator} objects for referencing files. + * These objects are not guaranteed to identify a file in a unique way. For + * instance, if only a file name is defined, this could mean a relative file + * name in the current directory, the name of a resource to be loaded from the + * class path, or something else. Before the file described by a + * {@code FileLocator} can be actually accessed, an unambiguous URL pointing to + * this file has to be obtained. This is the job of a + * {@code FileLocationStrategy}. + * </p> + * <p> + * This interface defines a method for locating a file provided as a + * {@code FileLocator} object. If location is successful, a URL is returned. A + * concrete implementation can perform arbitrary actions to search for the file + * in question at various places. There will also be an implementation allowing + * the combination of multiple {@code FileLocationStrategy} implementations; so + * a file can be searched using multiple strategies until one of them is + * successful. + * </p> + * + * @version $Id: $ + * @since 2.0 + */ +public interface FileLocationStrategy +{ + /** + * Tries to locate the specified file. The method also expects the + * {@code FileSystem} to be used. Note that the {@code FileLocator} object + * may also contain a {@code FileSystem}, but this is optional. The passed + * in {@code FileSystem} should be used, and callers must not pass a + * <b>null</b> reference for this argument. A concrete implementation has to + * evaluate the properties stored in the {@code FileLocator} object and try + * to match them to an existing file. If this can be done, a corresponding + * URL is returned. Otherwise, result is <b>null</b>. Implementations should + * not throw an exception (unless parameters are <b>null</b>) as there might + * be alternative strategies which can find the file in question. + * + * @param fileSystem the {@code FileSystem} to be used for this operation + * @param locator the object describing the file to be located + * @return a URL pointing to the referenced file if location was successful; + * <b>null</b> if the file could not be resolved + */ + URL locate(FileSystem fileSystem, FileLocator locator); +}