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SUMMARY: JavaDoc of com.mysql.jdbc.CompressedInputStream JAVADOC | Sourc code of com.mysql.jdbc.CompressedInputStream SOURCE | Download com.mysql.jdbc.CompressedInputStream DOWNLOAD | NESTED | FIELD | CONSTR | METHOD DETAIL: FIELD | CONSTR | METHOD

com.mysql.jdbc
Class CompressedInputStream  view CompressedInputStream download CompressedInputStream.java

java.lang.Object
  extended byjava.io.InputStream
      extended bycom.mysql.jdbc.CompressedInputStream
All Implemented Interfaces:
java.io.Closeable
class CompressedInputStream
extends java.io.InputStream

Used to de-compress packets from the MySQL server when protocol-level compression is turned on.

Version:
$Id: CompressedInputStream.java,v 1.1.4.5 2004/08/09 22:15:11 mmatthew Exp $

Field Summary
private  byte[] buffer
          The packet data after it has been un-compressed
private  java.io.InputStream in
          The stream we are reading from the server
private  java.util.zip.Inflater inflater
          The ZIP inflater used to un-compress packets
private  byte[] packetHeaderBuffer
          The buffer to read packet headers into
private  int pos
          The position we are reading from
 
Constructor Summary
CompressedInputStream(java.io.InputStream streamFromServer)
          Creates a new CompressedInputStream that reads the given stream from the server.
 
Method Summary
 int available()
          This method returns the number of bytes that can be read from this stream before a read can block.
 void close()
          This method closes the stream.
private  void getNextPacketFromServer()
          Retrieves and un-compressed (if necessary) the next packet from the server.
private  void getNextPacketIfRequired(int numBytes)
          Determines if another packet needs to be read from the server to be able to read numBytes from the stream.
 int read()
          This method reads an unsigned byte from the input stream and returns it as an int in the range of 0-255.
 int read(byte[] b)
          This method reads bytes from a stream and stores them into a caller supplied buffer.
 int read(byte[] b, int off, int len)
          This method read bytes from a stream and stores them into a caller supplied buffer.
private  int readFully(byte[] b, int off, int len)
           
 long skip(long n)
          This method skips the specified number of bytes in the stream.
 
Methods inherited from class java.io.InputStream
mark, markSupported, reset
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

inflater

private java.util.zip.Inflater inflater
The ZIP inflater used to un-compress packets

in

private java.io.InputStream in
The stream we are reading from the server

buffer

private byte[] buffer
The packet data after it has been un-compressed

pos

private int pos
The position we are reading from

packetHeaderBuffer

private byte[] packetHeaderBuffer
The buffer to read packet headers into

Constructor Detail

CompressedInputStream

public CompressedInputStream(java.io.InputStream streamFromServer)
Creates a new CompressedInputStream that reads the given stream from the server.

Method Detail

available

public int available()
              throws java.io.IOException
Description copied from class: java.io.InputStream
This method returns the number of bytes that can be read from this stream before a read can block. A return of 0 indicates that blocking might (or might not) occur on the very next read attempt.

This method always returns 0 in this class

close

public void close()
           throws java.io.IOException
Description copied from class: java.io.InputStream
This method closes the stream. Any futher attempts to read from the stream may generate an IOException

This method does nothing in this class, but subclasses may override this method in order to provide additional functionality.

read

public int read()
         throws java.io.IOException
Description copied from class: java.io.InputStream
This method reads an unsigned byte from the input stream and returns it as an int in the range of 0-255. This method also will return -1 if the end of the stream has been reached.

This method will block until the byte can be read.

read

public int read(byte[] b,
                int off,
                int len)
         throws java.io.IOException
Description copied from class: java.io.InputStream
This method read bytes from a stream and stores them into a caller supplied buffer. It starts storing the data at index off into the buffer and attempts to read len bytes. This method can return before reading the number of bytes requested. The actual number of bytes read is returned as an int. A -1 is returned to indicate the end of the stream.

This method will block until some data can be read.

This method operates by calling the single byte read() method in a loop until the desired number of bytes are read. The read loop stops short if the end of the stream is encountered or if an IOException is encountered on any read operation except the first. If the first attempt to read a bytes fails, the IOException is allowed to propagate upward. And subsequent IOException is caught and treated identically to an end of stream condition. Subclasses can (and should if possible) override this method to provide a more efficient implementation.

read

public int read(byte[] b)
         throws java.io.IOException
Description copied from class: java.io.InputStream
This method reads bytes from a stream and stores them into a caller supplied buffer. This method attempts to completely fill the buffer, but can return before doing so. The actual number of bytes read is returned as an int. A -1 is returned to indicate the end of the stream.

This method will block until some data can be read.

This method operates by calling an overloaded read method like so: read(b, 0, b.length)

skip

public long skip(long n)
          throws java.io.IOException
Description copied from class: java.io.InputStream
This method skips the specified number of bytes in the stream. It returns the actual number of bytes skipped, which may be less than the requested amount.

This method reads and discards bytes into a byte array until the specified number of bytes were skipped or until either the end of stream is reached or a read attempt returns a short count. Subclasses can override this metho to provide a more efficient implementation where one exists.

getNextPacketFromServer

private void getNextPacketFromServer()
                              throws java.io.IOException
Retrieves and un-compressed (if necessary) the next packet from the server.

getNextPacketIfRequired

private void getNextPacketIfRequired(int numBytes)
                              throws java.io.IOException
Determines if another packet needs to be read from the server to be able to read numBytes from the stream.

readFully

private final int readFully(byte[] b,
                            int off,
                            int len)
                     throws java.io.IOException
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SUMMARY: JavaDoc of com.mysql.jdbc.CompressedInputStream JAVADOC | Sourc code of com.mysql.jdbc.CompressedInputStream SOURCE | Download com.mysql.jdbc.CompressedInputStream DOWNLOAD | NESTED | FIELD | CONSTR | METHOD DETAIL: FIELD | CONSTR | METHOD