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 */
017 package org.apache.commons.io.input;
018
019 import java.io.FilterInputStream;
020 import java.io.IOException;
021 import java.io.InputStream;
022
023 /**
024 * A Proxy stream which acts as expected, that is it passes the method
025 * calls on to the proxied stream and doesn't change which methods are
026 * being called.
027 * <p>
028 * It is an alternative base class to FilterInputStream
029 * to increase reusability, because FilterInputStream changes the
030 * methods being called, such as read(byte[]) to read(byte[], int, int).
031 *
032 * @author Stephen Colebourne
033 * @version $Id: ProxyInputStream.java 610010 2008-01-08 14:50:59Z niallp $
034 */
035 public abstract class ProxyInputStream extends FilterInputStream {
036
037 /**
038 * Constructs a new ProxyInputStream.
039 *
040 * @param proxy the InputStream to delegate to
041 */
042 public ProxyInputStream(InputStream proxy) {
043 super(proxy);
044 // the proxy is stored in a protected superclass variable named 'in'
045 }
046
047 /**
048 * Invokes the delegate's <code>read()</code> method.
049 * @return the byte read or -1 if the end of stream
050 * @throws IOException if an I/O error occurs
051 */
052 public int read() throws IOException {
053 return in.read();
054 }
055
056 /**
057 * Invokes the delegate's <code>read(byte[])</code> method.
058 * @param bts the buffer to read the bytes into
059 * @return the number of bytes read or -1 if the end of stream
060 * @throws IOException if an I/O error occurs
061 */
062 public int read(byte[] bts) throws IOException {
063 return in.read(bts);
064 }
065
066 /**
067 * Invokes the delegate's <code>read(byte[], int, int)</code> method.
068 * @param bts the buffer to read the bytes into
069 * @param st The start offset
070 * @param end The number of bytes to read
071 * @return the number of bytes read or -1 if the end of stream
072 * @throws IOException if an I/O error occurs
073 */
074 public int read(byte[] bts, int st, int end) throws IOException {
075 return in.read(bts, st, end);
076 }
077
078 /**
079 * Invokes the delegate's <code>skip(long)</code> method.
080 * @param ln the number of bytes to skip
081 * @return the number of bytes to skipped or -1 if the end of stream
082 * @throws IOException if an I/O error occurs
083 */
084 public long skip(long ln) throws IOException {
085 return in.skip(ln);
086 }
087
088 /**
089 * Invokes the delegate's <code>available()</code> method.
090 * @return the number of available bytes
091 * @throws IOException if an I/O error occurs
092 */
093 public int available() throws IOException {
094 return in.available();
095 }
096
097 /**
098 * Invokes the delegate's <code>close()</code> method.
099 * @throws IOException if an I/O error occurs
100 */
101 public void close() throws IOException {
102 in.close();
103 }
104
105 /**
106 * Invokes the delegate's <code>mark(int)</code> method.
107 * @param idx read ahead limit
108 */
109 public synchronized void mark(int idx) {
110 in.mark(idx);
111 }
112
113 /**
114 * Invokes the delegate's <code>reset()</code> method.
115 * @throws IOException if an I/O error occurs
116 */
117 public synchronized void reset() throws IOException {
118 in.reset();
119 }
120
121 /**
122 * Invokes the delegate's <code>markSupported()</code> method.
123 * @return true if mark is supported, otherwise false
124 */
125 public boolean markSupported() {
126 return in.markSupported();
127 }
128
129 }