java.io
Class FilterInputStream

java.lang.Object
  extended by java.io.InputStream
      extended by java.io.FilterInputStream
All Implemented Interfaces:
Closeable, AutoCloseable
Direct Known Subclasses:
BufferedInputStream, DataInputStream

public class FilterInputStream
extends InputStream


Field Summary
protected  InputStream in
           
 
Constructor Summary
FilterInputStream(InputStream in)
           
 
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 readAheadLimit)
          Marks the current position in this input stream.
 int read()
          Reads the next byte of data from the input stream.
 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.io.InputStream
markSupported, read
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

in

protected InputStream in
Constructor Detail

FilterInputStream

public FilterInputStream(InputStream in)
Method Detail

available

public int available()
              throws IOException
Description copied from class: InputStream
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.

The available method for class InputStream always returns 0.

This method should be overridden by subclasses.

Overrides:
available in class InputStream
Returns:
the number of bytes that can be read from this input stream without blocking.
Throws:
IOException - if an I/O error occurs.

close

public void close()
           throws IOException
Description copied from class: InputStream
Closes this input stream and releases any system resources associated with the stream.

The close method of InputStream does nothing.

Specified by:
close in interface Closeable
Specified by:
close in interface AutoCloseable
Overrides:
close in class InputStream
Throws:
IOException - if an I/O error occurs.

mark

public void mark(int readAheadLimit)
Description copied from class: InputStream
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.

The mark method of InputStream does nothing.

Overrides:
mark in class InputStream
Parameters:
readAheadLimit - the maximum limit of bytes that can be read before the mark position becomes invalid.
See Also:
InputStream.reset()

read

public int read()
         throws IOException
Description copied from class: InputStream
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.

A subclass must provide an implementation of this method.

Specified by:
read in class InputStream
Returns:
the next byte of data, or -1 if the end of the stream is reached.
Throws:
IOException - if an I/O error occurs.

read

public int read(byte[] b,
                int off,
                int len)
         throws IOException
Description copied from class: InputStream
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 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:
IOException - if an I/O error occurs.
See Also:
InputStream.read()

reset

public void reset()
           throws IOException
Description copied from class: InputStream
Repositions this stream to the position at the time the mark method was last called on this input stream.

The general contract of reset is:

The method reset for class InputStream does nothing and always throws an IOException.

Overrides:
reset in class InputStream
Throws:
IOException - if this stream has not been marked or if the mark has been invalidated.
See Also:
InputStream.mark(int), IOException

skip

public long skip(long n)
          throws IOException
Description copied from class: InputStream
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.

The skip method of InputStream creates a byte array and then repeatedly reads into it until n bytes have been read or the end of the stream has been reached. Subclasses are encouraged to provide a more efficient implementation of this method.

Overrides:
skip in class InputStream
Parameters:
n - the number of bytes to be skipped.
Returns:
the actual number of bytes skipped.
Throws:
IOException - if an I/O error occurs.