OSMQ
v2.0.1

osmq.io
Class PacketInputStream

java.lang.Object
  extended byjava.io.InputStream
      extended byjava.io.FilterInputStream
          extended byosmq.io.PacketInputStream
All Implemented Interfaces:
ReaderStream
Direct Known Subclasses:
PacketFileInputStream, ZipPacketFileInputStream, ZipPacketInputStream

public class PacketInputStream
extends java.io.FilterInputStream
implements ReaderStream

An input stream filer that supports reading an input stream as packets of bytes. Each packet is preceeded with a size.

Note this class assumes a single reader and is NOT thread safe.


Constructor Summary
PacketInputStream(java.io.InputStream in)
           
 
Method Summary
 int getLastPacketSize()
           
 boolean isEOF()
          Returns true if the end of the stream was encountered.
 int read(byte[] b, int off, int len)
          Reads len bytes of data from the input stream into an array of bytes.
 byte[] readBytes()
          Returns the next packet of bytes from the underlying InputStream into a newly allocated byte array.
 int readBytes(byte[] target)
          Returns the next packet of bytes from the underlying InputStream and copies them into the byte array passed by the calling function.
 java.lang.String readln()
          Returns the next packet of bytes from the underlying InputStream returns it as a byte array.
 
Methods inherited from class java.io.FilterInputStream
available, close, mark, markSupported, read, read, reset, skip
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface osmq.io.ReaderStream
close
 

Constructor Detail

PacketInputStream

public PacketInputStream(java.io.InputStream in)
Method Detail

readBytes

public int readBytes(byte[] target)
              throws java.io.IOException
Returns the next packet of bytes from the underlying InputStream and copies them into the byte array passed by the calling function.

Specified by:
readBytes in interface ReaderStream
Throws:
java.io.IOException

isEOF

public boolean isEOF()
Returns true if the end of the stream was encountered.


readln

public java.lang.String readln()
                        throws java.io.IOException
Returns the next packet of bytes from the underlying InputStream returns it as a byte array.

This method blocks until the next packet is available.

Specified by:
readln in interface ReaderStream
Returns:
a String containing the packet bytes. The number of packet bytes in the array can be determined by calling getLastPacketSize()
Throws:
java.io.IOException - if an I/O error occurs.

getLastPacketSize

public int getLastPacketSize()

readBytes

public byte[] readBytes()
                 throws java.io.IOException
Returns the next packet of bytes from the underlying InputStream into a newly allocated byte array. This method blocks until the next packet is available.

Specified by:
readBytes in interface ReaderStream
Returns:
a byte array containing the packet. The number of packet bytes in the array can be determined by calling getLastPacketSize()
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 len bytes of data from the input stream into an array of bytes. The number of bytes actually read is returned as an integer.

NOTE This method blocks until input len is available, end of file is detected, or an exception is thrown. This is differs from the normal non-blocking InputStream contract that may return less than len

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.

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.
See Also:
InputStream.read(byte[], int, int)

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All Rights Reserved