    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.io.input;
    018
    019import java.io.IOException;
    020import java.io.Reader;
    021import java.util.function.Supplier;
    022
    023import org.apache.commons.io.function.Erase;
    024
    025/**
    026 * Always throws an exception from all {@link Reader} methods where {@link IOException} is declared.
    027 * <p>
    028 * This class is mostly useful for testing error handling.
    029 * </p>
    030 *
    031 * @since 2.7
    032 */
    033public class BrokenReader extends Reader {
    034
    035    /**
    036     * A singleton instance using a default IOException.
    037     *
    038     * @since 2.12.0
    039     */
    040    public static final BrokenReader INSTANCE = new BrokenReader();
    041
    042    /**
    043     * A supplier for the exception that is thrown by all methods of this class.
    044     */
    045    private final Supplier<Throwable> exceptionSupplier;
    046
    047    /**
    048     * Constructs a new reader that always throws an {@link IOException}.
    049     */
    050    public BrokenReader() {
    051        this(() -> new IOException("Broken reader"));
    052    }
    053
    054    /**
    055     * Constructs a new reader that always throws the given exception.
    056     *
    057     * @param exception the exception to be thrown.
    058     * @deprecated Use {@link #BrokenReader(Throwable)}.
    059     */
    060    @Deprecated
    061    public BrokenReader(final IOException exception) {
    062        this(() -> exception);
    063    }
    064
    065    /**
    066     * Constructs a new reader that always throws the supplied exception.
    067     *
    068     * @param exceptionSupplier a supplier for the IOException or RuntimeException to be thrown.
    069     * @since 2.12.0
    070     */
    071    public BrokenReader(final Supplier<Throwable> exceptionSupplier) {
    072        this.exceptionSupplier = exceptionSupplier;
    073    }
    074
    075    /**
    076     * Constructs a new reader that always throws the given exception.
    077     *
    078     * @param exception the exception to be thrown.
    079     * @since 2.16.0
    080     */
    081    public BrokenReader(final Throwable exception) {
    082        this(() -> exception);
    083    }
    084
    085    /**
    086     * Throws the configured exception.
    087     *
    088     * @throws IOException always throws the exception configured in a constructor.
    089     */
    090    @Override
    091    public void close() throws IOException {
    092        throw rethrow();
    093    }
    094
    095    /**
    096     * Throws the configured exception.
    097     *
    098     * @param readAheadLimit ignored.
    099     * @throws IOException always throws the exception configured in a constructor.
    100     */
    101    @Override
    102    public void mark(final int readAheadLimit) throws IOException {
    103        throw rethrow();
    104    }
    105
    106    /**
    107     * Throws the configured exception.
    108     *
    109     * @param cbuf ignored.
    110     * @param off  ignored.
    111     * @param len  ignored.
    112     * @return nothing.
    113     * @throws IOException always throws the exception configured in a constructor.
    114     */
    115    @Override
    116    public int read(final char[] cbuf, final int off, final int len) throws IOException {
    117        throw rethrow();
    118    }
    119
    120    /**
    121     * Throws the configured exception.
    122     *
    123     * @return nothing.
    124     * @throws IOException always throws the exception configured in a constructor.
    125     */
    126    @Override
    127    public boolean ready() throws IOException {
    128        throw rethrow();
    129    }
    130
    131    /**
    132     * Throws the configured exception.
    133     *
    134     * @throws IOException always throws the exception configured in a constructor.
    135     */
    136    @Override
    137    public void reset() throws IOException {
    138        throw rethrow();
    139    }
    140
    141    /**
    142     * Throws the configured exception from its supplier.
    143     *
    144     * @return Throws the configured exception from its supplier.
    145     */
    146    private RuntimeException rethrow() {
    147        return Erase.rethrow(exceptionSupplier.get());
    148    }
    149
    150    /**
    151     * Throws the configured exception.
    152     *
    153     * @param n ignored.
    154     * @return nothing.
    155     * @throws IOException always throws the exception configured in a constructor.
    156     */
    157    @Override
    158    public long skip(final long n) throws IOException {
    159        throw rethrow();
    160    }
    161
    162}