SteerableInputStream


1   package org.columba.core.io;
2   
3   import java.io.FilterInputStream  ;
4   import java.io.IOException  ;
5   import java.io.InputStream  ;
6   
7   public class SteerableInputStream extends FilterInputStream   {
8   
9       private long lengthLeft;
10  
11      private long position;
12  
13      public SteerableInputStream(InputStream   in) {
14          super(in);
15  
16          try {
17              lengthLeft = in.available();
18          } catch (IOException   e) {
19              lengthLeft = 0;
20          }
21      }
22  
23      /**
24       * {@inheritDoc}
25       */
26      @Override  
27      public int read() throws IOException   {
28          if (lengthLeft > 0) {
29              int read = super.read();
30              if (read != -1) {
31                  lengthLeft--;
32              }
33              position++;
34              return read;
35          }
36          return -1;
37      }
38  
39      /**
40       * {@inheritDoc}
41       */
42      @Override  
43      public int read(byte[] b, int off, int len) throws IOException   {
44          if (len > lengthLeft) {
45              int correctedLen = (int) lengthLeft;
46              int read = super.read(b, off, correctedLen);
47              lengthLeft -= read;
48              position += read;
49              return read;
50          }
51          int read = super.read(b, off, len);
52          lengthLeft -= read;
53          position += read;
54          return read;
55  
56      }
57  
58      /**
59       * @return Returns the lengthLeft.
60       */
61      public long getLengthLeft() {
62          return lengthLeft;
63      }
64  
65      /**
66       * @param lengthLeft
67       *            The lengthLeft to set.
68       */
69      public void setLengthLeft(long lengthLeft) throws IOException   {
70          this.lengthLeft = Math.min(lengthLeft, in.available());
71      }
72  
73      /**
74       * @return Returns the position.
75       */
76      public long getPosition() {
77          return position;
78      }
79  
80      /**
81       * @param position
82       *            The position to set.
83       */
84      public void setPosition(long newposition) throws IOException   {
85          long skipped = in.skip(newposition - position);
86          lengthLeft = Math.max(0, lengthLeft - skipped);
87          position = newposition;
88      }
89  
90      
91      /**
92       * {@inheritDoc}
93       */
94      @Override  
95      public int available() throws IOException   {
96          return (int) lengthLeft;
97      }
98  
99      
100     /**
101      * {@inheritDoc}
102      */
103     @Override  
104     public void close() throws IOException   {
105         // do nothinh here ... use finalClose
106     }
107 
108     
109     /**
110      * @throws IOException
111      */
112     public void finalClose() throws IOException   {
113         super.close();
114     }
115 
116 }
117
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