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      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.FilterInputStream;
     20 import java.io.IOException;
     21 import java.io.InputStream;
     22 
     23 /**
     24  * A Proxy stream which acts as expected, that is it passes the method
     25  * calls on to the proxied stream and doesn't change which methods are
     26  * being called.
     27  * <p>
     28  * It is an alternative base class to FilterInputStream
     29  * to increase reusability, because FilterInputStream changes the
     30  * methods being called, such as read(byte[]) to read(byte[], int, int).
     31  *
     32  * @author Stephen Colebourne
     33  * @version $Id: ProxyInputStream.java 610010 2008-01-08 14:50:59Z niallp $
     34  */
     35 public abstract class ProxyInputStream extends FilterInputStream {
     36 
     37     /**
     38      * Constructs a new ProxyInputStream.
     39      *
     40      * @param proxy  the InputStream to delegate to
     41      */
     42     public ProxyInputStream(InputStream proxy) {
     43         super(proxy);
     44         // the proxy is stored in a protected superclass variable named 'in'
     45     }
     46 
     47     /**
     48      * Invokes the delegate's <code>read()</code> method.
     49      * @return the byte read or -1 if the end of stream
     50      * @throws IOException if an I/O error occurs
     51      */
     52     public int read() throws IOException {
     53         return in.read();
     54     }
     55 
     56     /**
     57      * Invokes the delegate's <code>read(byte[])</code> method.
     58      * @param bts the buffer to read the bytes into
     59      * @return the number of bytes read or -1 if the end of stream
     60      * @throws IOException if an I/O error occurs
     61      */
     62     public int read(byte[] bts) throws IOException {
     63         return in.read(bts);
     64     }
     65 
     66     /**
     67      * Invokes the delegate's <code>read(byte[], int, int)</code> method.
     68      * @param bts the buffer to read the bytes into
     69      * @param st The start offset
     70      * @param end The number of bytes to read
     71      * @return the number of bytes read or -1 if the end of stream
     72      * @throws IOException if an I/O error occurs
     73      */
     74     public int read(byte[] bts, int st, int end) throws IOException {
     75         return in.read(bts, st, end);
     76     }
     77 
     78     /**
     79      * Invokes the delegate's <code>skip(long)</code> method.
     80      * @param ln the number of bytes to skip
     81      * @return the number of bytes to skipped or -1 if the end of stream
     82      * @throws IOException if an I/O error occurs
     83      */
     84     public long skip(long ln) throws IOException {
     85         return in.skip(ln);
     86     }
     87 
     88     /**
     89      * Invokes the delegate's <code>available()</code> method.
     90      * @return the number of available bytes
     91      * @throws IOException if an I/O error occurs
     92      */
     93     public int available() throws IOException {
     94         return in.available();
     95     }
     96 
     97     /**
     98      * Invokes the delegate's <code>close()</code> method.
     99      * @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 }
    130