1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 package org.apache.commons.io.input; 18 19 import java.io.IOException; 20 import java.io.InputStream; 21 import java.util.Objects; 22 23 import org.apache.commons.io.IOUtils; 24 25 /** 26 * An {@link InputStream} that repeats provided bytes for given target byte count. 27 * <p> 28 * Closing this input stream has no effect. The methods in this class can be called after the stream has been closed 29 * without generating an {@link IOException}. 30 * </p> 31 * 32 * @see InfiniteCircularInputStream 33 * @since 2.8.0 34 */ 35 public class CircularInputStream extends InputStream { 36 37 /** 38 * Throws an {@link IllegalArgumentException} if the input contains -1. 39 * 40 * @param repeatContent input to validate. 41 * @return the input. 42 */ validate(final byte[] repeatContent)43 private static byte[] validate(final byte[] repeatContent) { 44 Objects.requireNonNull(repeatContent, "repeatContent"); 45 for (final byte b : repeatContent) { 46 if (b == IOUtils.EOF) { 47 throw new IllegalArgumentException("repeatContent contains the end-of-stream marker " + IOUtils.EOF); 48 } 49 } 50 return repeatContent; 51 } 52 53 private long byteCount; 54 private int position = -1; 55 private final byte[] repeatedContent; 56 private final long targetByteCount; 57 58 /** 59 * Constructs an instance from the specified array of bytes. 60 * 61 * @param repeatContent Input buffer to be repeated this buffer is not copied. 62 * @param targetByteCount How many bytes the read. A negative number means an infinite target count. 63 */ CircularInputStream(final byte[] repeatContent, final long targetByteCount)64 public CircularInputStream(final byte[] repeatContent, final long targetByteCount) { 65 this.repeatedContent = validate(repeatContent); 66 if (repeatContent.length == 0) { 67 throw new IllegalArgumentException("repeatContent is empty."); 68 } 69 this.targetByteCount = targetByteCount; 70 } 71 72 @Override read()73 public int read() { 74 if (targetByteCount >= 0) { 75 if (byteCount == targetByteCount) { 76 return IOUtils.EOF; 77 } 78 byteCount++; 79 } 80 position = (position + 1) % repeatedContent.length; 81 return repeatedContent[position] & 0xff; 82 } 83 84 } 85