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 22 /** 23 * Proxy stream that closes and discards the underlying stream as soon as the 24 * end of input has been reached or when the stream is explicitly closed. 25 * Not even a reference to the underlying stream is kept after it has been 26 * closed, so any allocated in-memory buffers can be freed even if the 27 * client application still keeps a reference to the proxy stream. 28 * <p> 29 * This class is typically used to release any resources related to an open 30 * stream as soon as possible even if the client application (by not explicitly 31 * closing the stream when no longer needed) or the underlying stream (by not 32 * releasing resources once the last byte has been read) do not do that. 33 * 34 * @version $Id: AutoCloseInputStream.java 610010 2008-01-08 14:50:59Z niallp $ 35 * @since Commons IO 1.4 36 */ 37 public class AutoCloseInputStream extends ProxyInputStream { 38 39 /** 40 * Creates an automatically closing proxy for the given input stream. 41 * 42 * @param in underlying input stream 43 */ 44 public AutoCloseInputStream(InputStream in) { 45 super(in); 46 } 47 48 /** 49 * Closes the underlying input stream and replaces the reference to it 50 * with a {@link ClosedInputStream} instance. 51 * <p> 52 * This method is automatically called by the read methods when the end 53 * of input has been reached. 54 * <p> 55 * Note that it is safe to call this method any number of times. The original 56 * underlying input stream is closed and discarded only once when this 57 * method is first called. 58 * 59 * @throws IOException if the underlying input stream can not be closed 60 */ 61 public void close() throws IOException { 62 in.close(); 63 in = new ClosedInputStream(); 64 } 65 66 /** 67 * Reads and returns a single byte from the underlying input stream. 68 * If the underlying stream returns -1, the {@link #close()} method is 69 * called to automatically close and discard the stream. 70 * 71 * @return next byte in the stream, or -1 if no more bytes are available 72 * @throws IOException if the stream could not be read or closed 73 */ 74 public int read() throws IOException { 75 int n = in.read(); 76 if (n == -1) { 77 close(); 78 } 79 return n; 80 } 81 82 /** 83 * Reads and returns bytes from the underlying input stream to the given 84 * buffer. If the underlying stream returns -1, the {@link #close()} method 85 * i called to automatically close and discard the stream. 86 * 87 * @param b buffer to which bytes from the stream are written 88 * @return number of bytes read, or -1 if no more bytes are available 89 * @throws IOException if the stream could not be read or closed 90 */ 91 public int read(byte[] b) throws IOException { 92 int n = in.read(b); 93 if (n == -1) { 94 close(); 95 } 96 return n; 97 } 98 99 /** 100 * Reads and returns bytes from the underlying input stream to the given 101 * buffer. If the underlying stream returns -1, the {@link #close()} method 102 * i called to automatically close and discard the stream. 103 * 104 * @param b buffer to which bytes from the stream are written 105 * @param off start offset within the buffer 106 * @param len maximum number of bytes to read 107 * @return number of bytes read, or -1 if no more bytes are available 108 * @throws IOException if the stream could not be read or closed 109 */ 110 public int read(byte[] b, int off, int len) throws IOException { 111 int n = in.read(b, off, len); 112 if (n == -1) { 113 close(); 114 } 115 return n; 116 } 117 118 /** 119 * Ensures that the stream is closed before it gets garbage-collected. 120 * As mentioned in {@link #close()}, this is a no-op if the stream has 121 * already been closed. 122 * @throws Throwable if an error occurs 123 */ 124 protected void finalize() throws Throwable { 125 close(); 126 super.finalize(); 127 } 128 129 } 130
