001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *     http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.configuration2.io;
018
019import java.io.IOException;
020import java.io.Reader;
021import java.io.Writer;
022
023import org.apache.commons.configuration2.ex.ConfigurationException;
024
025/**
026 * <p>
027 * Definition of an interface to be implemented by objects which know how to
028 * read and write themselves from or to a character stream.
029 * </p>
030 * <p>
031 * This interface is implemented by special implementations of the
032 * {@code Configuration} interface which are associated with a file. It demands
033 * only basic methods for doing I/O based on character stream objects. Based on
034 * these methods it is possible to implement other methods which operate on
035 * files, file names, URLs, etc.
036 * </p>
037 * <p>
038 * <strong>Note that the methods defined by this interface are not intended to
039 * be called directly by client code!</strong> Rather, they are used internally
040 * when doing I/O operations with a {@link FileHandler}. A {@code FileHandler}
041 * supports additional functionality (e.g. it evaluates some additional
042 * interfaces the {@code FileBased} object may implement); this functionality
043 * is not available on a direct method invocation, so this may lead to
044 * unpredictable results.
045 * </p>
046 *
047 */
048public interface FileBased
049{
050    /**
051     * Reads the content of this object from the given reader.
052     * <strong>Client code should not call this method directly, but use a
053     * {@code FileHandler} for reading data.</strong>
054     *
055     * @param in the reader
056     * @throws IOException if an I/O error occurs
057     * @throws ConfigurationException if a non-I/O related problem occurs, e.g.
058     *         the data read does not have the expected format
059     */
060    void read(Reader in) throws ConfigurationException, IOException;
061
062    /**
063     * Writes the content of this object to the given writer.
064     * <strong>Client code should not call this method directly, but use a
065     * {@code FileHandler} for writing data.</strong>
066     *
067     * @param out the writer
068     * @throws IOException if an I/O error occurs
069     * @throws ConfigurationException if a non-I/O related problem occurs, e.g.
070     *         the data read does not have the expected format
071     */
072    void write(Writer out) throws ConfigurationException, IOException;
073}