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    }