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.InputStream; 021import java.util.Objects; 022 023import org.apache.commons.io.IOUtils; 024 025/** 026 * 027 * An {@link InputStream} that repeats provided bytes for given target byte count. 028 * <p> 029 * Closing this input stream has no effect. The methods in this class can be called after the stream has been closed 030 * without generating an {@link IOException}. 031 * </p> 032 * 033 * @see InfiniteCircularInputStream 034 * @since 2.8.0 035 */ 036public class CircularInputStream extends InputStream { 037 038 /** 039 * Throws an {@link IllegalArgumentException} if the input contains -1. 040 * 041 * @param repeatContent input to validate. 042 * @return the input. 043 */ 044 private static byte[] validate(final byte[] repeatContent) { 045 Objects.requireNonNull(repeatContent, "repeatContent"); 046 for (final byte b : repeatContent) { 047 if (b == IOUtils.EOF) { 048 throw new IllegalArgumentException("repeatContent contains the end-of-stream marker " + IOUtils.EOF); 049 } 050 } 051 return repeatContent; 052 } 053 054 private long byteCount; 055 private int position = -1; 056 private final byte[] repeatedContent; 057 private final long targetByteCount; 058 059 /** 060 * Creates an instance from the specified array of bytes. 061 * 062 * @param repeatContent Input buffer to be repeated this buffer is not copied. 063 * @param targetByteCount How many bytes the read. A negative number means an infinite target count. 064 */ 065 public CircularInputStream(final byte[] repeatContent, final long targetByteCount) { 066 this.repeatedContent = validate(repeatContent); 067 if (repeatContent.length == 0) { 068 throw new IllegalArgumentException("repeatContent is empty."); 069 } 070 this.targetByteCount = targetByteCount; 071 } 072 073 @Override 074 public int read() { 075 if (targetByteCount >= 0) { 076 if (byteCount == targetByteCount) { 077 return IOUtils.EOF; 078 } 079 byteCount++; 080 } 081 position = (position + 1) % repeatedContent.length; 082 return repeatedContent[position] & 0xff; 083 } 084 085}