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 read and write themselves from or to a
028 * character stream.
029 * </p>
030 * <p>
031 * This interface is implemented by special implementations of the {@code Configuration} interface which are associated
032 * with a file. It demands only basic methods for doing I/O based on character stream objects. Based on these methods it
033 * is possible to implement other methods which operate on files, file names, URLs, etc.
034 * </p>
035 * <p>
036 * <strong>Note that the methods defined by this interface are not intended to be called directly by client
037 * code!</strong> Rather, they are used internally when doing I/O operations with a {@link FileHandler}. A
038 * {@code FileHandler} supports additional functionality (e.g. it evaluates some additional interfaces the
039 * {@code FileBased} object may implement); this functionality is not available on a direct method invocation, so this
040 * may lead to unpredictable results.
041 * </p>
042 */
043public interface FileBased {
044    /**
045     * Reads the content of this object from the given reader. <strong>Client code should not call this method directly, but
046     * use a {@code FileHandler} for reading data.</strong>
047     *
048     * @param in the reader
049     * @throws IOException if an I/O error occurs.
050     * @throws ConfigurationException if a non-I/O related problem occurs, e.g. the data read does not have the expected
051     *         format
052     */
053    void read(Reader in) throws ConfigurationException, IOException;
054
055    /**
056     * Writes the content of this object to the given writer. <strong>Client code should not call this method directly, but
057     * use a {@code FileHandler} for writing data.</strong>
058     *
059     * @param out the writer
060     * @throws IOException if an I/O error occurs.
061     * @throws ConfigurationException if a non-I/O related problem occurs, e.g. the data read does not have the expected
062     *         format
063     */
064    void write(Writer out) throws ConfigurationException, IOException;
065}