java.io
Class InputStream

java.lang.Object
  |
  +--java.io.InputStream
Direct Known Subclasses:
ByteArrayInputStream, FileInputStream, FilterInputStream, PipedInputStream, SequenceInputStream, StringBufferInputStream

public abstract class InputStream
extends Object

An abstract class representing an input stream of bytes. All InputStreams are based on this class.

See Also:
OutputStream, FilterInputStream, BufferedInputStream, DataInputStream, ByteArrayInputStream, PushbackInputStream

Constructor Summary
InputStream()
           
 
Method Summary
 int available()
          Returns the number of bytes that can be read without blocking.
 void close()
          Closes the input stream.
 void mark(int readlimit)
          Marks the current position in the input stream.
 boolean markSupported()
          Returns a boolean indicating whether or not this stream type supports mark/reset.
abstract  int read()
          Reads a byte of data.
 int read(byte[] b)
          Reads into an array of bytes.
 int read(byte[] b, int off, int len)
          Reads into an array of bytes.
 void reset()
          Repositions the stream to the last marked position.
 long skip(long n)
          Skips n bytes of input.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

InputStream

public InputStream()
Method Detail

read

public abstract int read()
                  throws IOException
Reads a byte of data. This method will block if no input is available.

Returns:
the byte read, or -1 if the end of the stream is reached.
Throws:
IOException - If an I/O error has occurred.

read

public int read(byte[] b)
         throws IOException
Reads into an array of bytes. This method will block until some input is available.

Parameters:
b - the buffer into which the data is read
Returns:
the actual number of bytes read, -1 is returned when the end of the stream is reached.
Throws:
IOException - If an I/O error has occurred.

read

public int read(byte[] b,
                int off,
                int len)
         throws IOException
Reads into an array of bytes. This method will block until some input is available.

Parameters:
b - the buffer into which the data is read
off - the start offset of the data
len - the maximum number of bytes read
Returns:
the actual number of bytes read, -1 is returned when the end of the stream is reached.
Throws:
IOException - If an I/O error has occurred.

skip

public long skip(long n)
          throws IOException
Skips n bytes of input.

Parameters:
n - the number of bytes to be skipped
Returns:
the actual number of bytes skipped.
Throws:
IOException - If an I/O error has occurred.

available

public int available()
              throws IOException
Returns the number of bytes that can be read without blocking.

Returns:
the number of available bytes.
IOException

close

public void close()
           throws IOException
Closes the input stream. Must be called to release any resources associated with the stream.

Throws:
IOException - If an I/O error has occurred.

mark

public void mark(int readlimit)
Marks the current position in the input stream. A subsequent call to reset() will reposition the stream at the last marked position so that subsequent reads will re-read the same bytes. The stream promises to allow readlimit bytes to be read before the mark position gets invalidated.

Parameters:
readlimit - the maximum limit of bytes allowed to be read before the mark position becomes invalid.

reset

public void reset()
           throws IOException
Repositions the stream to the last marked position. If the stream has not been marked, or if the mark has been invalidated, an IOException is thrown. Stream marks are intended to be used in situations where you need to read ahead a little to see what's in the stream. Often this is most easily done by invoking some general parser. If the stream is of the type handled by the parser, it just chugs along happily. If the stream is not of that type, the parser should toss an exception when it fails, which, if it happens within readlimit bytes, allows the outer code to reset the stream and try another parser.

Throws:
IOException - If the stream has not been marked or if the mark has been invalidated.

markSupported

public boolean markSupported()
Returns a boolean indicating whether or not this stream type supports mark/reset.

Returns:
true if this stream type supports mark/reset; false otherwise.