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 18package java.util.zip; 19 20import java.io.FilterInputStream; 21import java.io.IOException; 22import java.io.InputStream; 23import java.util.Arrays; 24import libcore.io.Streams; 25 26/** 27 * An {@code InputStream} filter to compress data. Callers read 28 * compressed data in the "deflate" format from the uncompressed 29 * underlying stream. 30 * @since 1.6 31 */ 32public class DeflaterInputStream extends FilterInputStream { 33 private static final int DEFAULT_BUFFER_SIZE = 1024; 34 35 protected final Deflater def; 36 protected final byte[] buf; 37 38 private boolean closed = false; 39 private boolean available = true; 40 41 /** 42 * Constructs a {@code DeflaterInputStream} with a new {@code Deflater} and an 43 * implementation-defined default internal buffer size. {@code in} is a source of 44 * uncompressed data, and this stream will be a source of compressed data. 45 * 46 * @param in the source {@code InputStream} 47 */ 48 public DeflaterInputStream(InputStream in) { 49 this(in, new Deflater(), DEFAULT_BUFFER_SIZE); 50 } 51 52 /** 53 * Constructs a {@code DeflaterInputStream} with the given {@code Deflater} and an 54 * implementation-defined default internal buffer size. {@code in} is a source of 55 * uncompressed data, and this stream will be a source of compressed data. 56 * 57 * @param in the source {@code InputStream} 58 * @param deflater the {@code Deflater} to be used for compression 59 */ 60 public DeflaterInputStream(InputStream in, Deflater deflater) { 61 this(in, deflater, DEFAULT_BUFFER_SIZE); 62 } 63 64 /** 65 * Constructs a {@code DeflaterInputStream} with the given {@code Deflater} and 66 * given internal buffer size. {@code in} is a source of 67 * uncompressed data, and this stream will be a source of compressed data. 68 * 69 * @param in the source {@code InputStream} 70 * @param deflater the {@code Deflater} to be used for compression 71 * @param bufferSize the length in bytes of the internal buffer 72 */ 73 public DeflaterInputStream(InputStream in, Deflater deflater, int bufferSize) { 74 super(in); 75 if (in == null) { 76 throw new NullPointerException("in == null"); 77 } else if (deflater == null) { 78 throw new NullPointerException("deflater == null"); 79 } 80 if (bufferSize <= 0) { 81 throw new IllegalArgumentException(); 82 } 83 this.def = deflater; 84 this.buf = new byte[bufferSize]; 85 } 86 87 /** 88 * Closes the underlying input stream and discards any remaining uncompressed 89 * data. 90 */ 91 @Override 92 public void close() throws IOException { 93 closed = true; 94 def.end(); 95 in.close(); 96 } 97 98 /** 99 * Reads a byte from the compressed input stream. The result will be a byte of compressed 100 * data corresponding to an uncompressed byte or bytes read from the underlying stream. 101 * 102 * @return the byte or -1 if the end of the stream has been reached. 103 */ 104 @Override public int read() throws IOException { 105 return Streams.readSingleByte(this); 106 } 107 108 /** 109 * Reads compressed data into a byte buffer. The result will be bytes of compressed 110 * data corresponding to an uncompressed byte or bytes read from the underlying stream. 111 * @return the number of bytes read or -1 if the end of the compressed input 112 * stream has been reached. 113 */ 114 @Override public int read(byte[] buffer, int offset, int byteCount) throws IOException { 115 checkClosed(); 116 Arrays.checkOffsetAndCount(buffer.length, offset, byteCount); 117 if (byteCount == 0) { 118 return 0; 119 } 120 121 if (!available) { 122 return -1; 123 } 124 125 int count = 0; 126 while (count < byteCount && !def.finished()) { 127 if (def.needsInput()) { 128 // read data from input stream 129 int bytesRead = in.read(buf); 130 if (bytesRead == -1) { 131 def.finish(); 132 } else { 133 def.setInput(buf, 0, bytesRead); 134 } 135 } 136 int bytesDeflated = def.deflate(buf, 0, Math.min(buf.length, byteCount - count)); 137 if (bytesDeflated == -1) { 138 break; 139 } 140 System.arraycopy(buf, 0, buffer, offset + count, bytesDeflated); 141 count += bytesDeflated; 142 } 143 if (count == 0) { 144 count = -1; 145 available = false; 146 } 147 return count; 148 } 149 150 /** 151 * {@inheritDoc} 152 * <p>Note: if {@code n > Integer.MAX_VALUE}, this stream will only attempt to 153 * skip {@code Integer.MAX_VALUE} bytes. 154 */ 155 @Override 156 public long skip(long byteCount) throws IOException { 157 byteCount = Math.min(Integer.MAX_VALUE, byteCount); 158 return Streams.skipByReading(this, byteCount); 159 } 160 161 /** 162 * Returns 0 when when this stream has exhausted its input; and 1 otherwise. 163 * A result of 1 does not guarantee that further bytes can be returned, 164 * with or without blocking. 165 * 166 * <p>Although consistent with the RI, this behavior is inconsistent with 167 * {@link InputStream#available()}, and violates the <a 168 * href="http://en.wikipedia.org/wiki/Liskov_substitution_principle">Liskov 169 * Substitution Principle</a>. This method should not be used. 170 * 171 * @return 0 if no further bytes are available. Otherwise returns 1, 172 * which suggests (but does not guarantee) that additional bytes are 173 * available. 174 * @throws IOException if this stream is closed or an error occurs 175 */ 176 @Override 177 public int available() throws IOException { 178 checkClosed(); 179 return available ? 1 : 0; 180 } 181 182 /** 183 * Returns false because {@code DeflaterInputStream} does not support 184 * {@code mark}/{@code reset}. 185 */ 186 @Override 187 public boolean markSupported() { 188 return false; 189 } 190 191 /** 192 * This operation is not supported and does nothing. 193 */ 194 @Override 195 public void mark(int limit) { 196 } 197 198 /** 199 * This operation is not supported and throws {@code IOException}. 200 */ 201 @Override 202 public void reset() throws IOException { 203 throw new IOException(); 204 } 205 206 private void checkClosed() throws IOException { 207 if (closed) { 208 throw new IOException("Stream is closed"); 209 } 210 } 211} 212