qflib 0.98.1

de.qfs.lib.util
Class InputStreamAdapter

java.lang.Object
  |
  +--java.io.InputStream
        |
        +--de.qfs.lib.util.InputStreamAdapter
Direct Known Subclasses:
CountingInputStream

public class InputStreamAdapter
extends java.io.InputStream

This is a baseclass for InputStream adapters. It delegates all calls to some other InputStream. Derived classes can overload the methods to modify the InputStream's behaviour.

Since:
0.96.0
Version:
$Revision: 1.2 $
Author:
Gregor Schmid

Field Summary
protected  java.io.InputStream stream
          The InputStream used for delegation.
 
Constructor Summary
InputStreamAdapter(java.io.InputStream stream)
          Create a new InputStreamAdapter.
 
Method Summary
 int available()
          Returns the number of bytes that can be read (or skipped over) from this input stream without blocking by the next caller of a method for this input stream.
 void close()
          Closes this input stream and releases any system resources associated with the stream.
 void mark(int readlimit)
          Marks the current position in this input stream.
 boolean markSupported()
          Tests if this input stream supports the mark and reset methods.
 int read()
          Reads the next byte of data from the input stream.
 int read(byte[] b)
          Reads some number of bytes from the input stream and stores them into the buffer array b.
 int read(byte[] b, int off, int len)
          Reads up to len bytes of data from the input stream into an array of bytes.
 void reset()
          Repositions this stream to the position at the time the mark method was last called on this input stream.
 long skip(long n)
          Skips over and discards n bytes of data from this input stream.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

stream

protected java.io.InputStream stream
The InputStream used for delegation.
Constructor Detail

InputStreamAdapter

public InputStreamAdapter(java.io.InputStream stream)
Create a new InputStreamAdapter.
Parameters:
stream - The InputStream used for delegation.
Method Detail

available

public int available()
              throws java.io.IOException
Returns the number of bytes that can be read (or skipped over) from this input stream without blocking by the next caller of a method for this input stream. The next caller might be the same thread or or another thread.
Overrides:
available in class java.io.InputStream
Returns:
The number of bytes that can be read from this input stream without blocking.
Throws:
java.io.IOException - If an I/O error occurs.

close

public void close()
           throws java.io.IOException
Closes this input stream and releases any system resources associated with the stream.
Overrides:
close in class java.io.InputStream
Throws:
java.io.IOException - If an I/O error occurs.

mark

public void mark(int readlimit)
Marks the current position in this input stream. A subsequent call to the reset method repositions this stream at the last marked position so that subsequent reads re-read the same bytes.

The readlimit arguments tells this input stream to allow that many bytes to be read before the mark position gets invalidated.

The general contract of mark is that, if the method markSupported returns true, the stream somehow remembers all the bytes read after the call to mark and stands ready to supply those same bytes again if and whenever the method reset is called. However, the stream is not required to remember any data at all if more than readlimit bytes are read from the stream before reset is called. Marks the current position in this input stream.

Overrides:
mark in class java.io.InputStream
Parameters:
readlimit - The maximum limit of bytes that can be read before the mark position becomes invalid.

markSupported

public boolean markSupported()
Tests if this input stream supports the mark and reset methods.
Overrides:
markSupported in class java.io.InputStream
Returns:
True if this true type supports the mark and reset method, false otherwise.

read

public int read()
         throws java.io.IOException
Reads the next byte of data from the input stream. The value byte is returned as an int in the range 0 to 255. If no byte is available because the end of the stream has been reached, the value -1 is returned. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown.
Overrides:
read in class java.io.InputStream
Returns:
The next byte of data, or -1 if the end of the stream is reached.
Throws:
java.io.IOException - If an I/O error occurs.

read

public int read(byte[] b)
         throws java.io.IOException
Reads some number of bytes from the input stream and stores them into the buffer array b. The number of bytes actually read is returned as an integer. This method blocks until input data is available, end of file is detected, or an exception is thrown.

If b is null, a NullPointerException is thrown. If the length of b is zero, then no bytes are read and 0 is returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at end of file, the value -1 is returned; otherwise, at least one byte is read and stored into b.

The first byte read is stored into element b[0], the next one into b[1], and so on. The number of bytes read is, at most, equal to the length of b. Let k be the number of bytes actually read; these bytes will be stored in elements b[0] through b[k-1], leaving elements b[k] through b[b.length-1] unaffected.

If the first byte cannot be read for any reason other than end of file, then an IOException is thrown. In particular, an IOException is thrown if the input stream has been closed.

Overrides:
read in class java.io.InputStream
Parameters:
b - The buffer into which the data is read.
Returns:
The total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.
Throws:
java.io.IOException - If an I/O error occurs.

read

public int read(byte[] b,
                int off,
                int len)
         throws java.io.IOException
Reads up to len bytes of data from the input stream into an array of bytes. An attempt is made to read as many as len bytes, but a smaller number may be read, possibly zero. The number of bytes actually read is returned as an integer.

This method blocks until input data is available, end of file is detected, or an exception is thrown.

If b is null, a NullPointerException is thrown.

If off is negative, or len is negative, or off+len is greater than the length of the array b, then an IndexOutOfBoundsException is thrown.

If len is zero, then no bytes are read and 0 is returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at end of file, the value -1 is returned; otherwise, at least one byte is read and stored into b.

The first byte read is stored into element b[off], the next one into b[off+1], and so on. The number of bytes read is, at most, equal to len. Let k be the number of bytes actually read; these bytes will be stored in elements b[off] through b[off+k-1], leaving elements b[off+k] through b[off+len-1] unaffected.

In every case, elements b[0] through b[off] and elements b[off+len] through b[b.length-1] are unaffected.

If the first byte cannot be read for any reason other than end of file, then an IOException is thrown. In particular, an IOException is thrown if the input stream has been closed.

The read(b, off, len) method for class InputStream simply calls the method read() repeatedly. If the first such call results in an IOException, that exception is returned from the call to the read(b, off, len) method. If any subsequent call to read() results in a IOException, the exception is caught and treated as if it were end of file; the bytes read up to that point are stored into b and the number of bytes read before the exception occurred is returned. Subclasses are encouraged to provide a more efficient implementation of this method.

Overrides:
read in class java.io.InputStream
Parameters:
b - The buffer into which the data is read.
off - The start offset in array b at which the data is written.
len - The maximum number of bytes to read.
Returns:
The total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.
Throws:
java.io.IOException - If an I/O error occurs.

reset

public void reset()
           throws java.io.IOException
Repositions this stream to the position at the time the mark method was last called on this input stream.
Overrides:
reset in class java.io.InputStream
Throws:
java.io.IOException - If an I/O error occurs.

skip

public long skip(long n)
          throws java.io.IOException
Skips over and discards n bytes of data from this input stream. The skip method may, for a variety of reasons, end up skipping over some smaller number of bytes, possibly 0. This may result from any of a number of conditions; reaching end of file before n bytes have been skipped is only one possibility. The actual number of bytes skipped is returned. If n is negative, no bytes are skipped.
Overrides:
skip in class java.io.InputStream
Parameters:
n - The number of bytes to be skipped.
Returns:
The actual number of bytes skipped.
Throws:
java.io.IOException - If an I/O error occurs.

qflib 0.98.1