org.objectweb.cjdbc.common.stream
Class CJDBCOutputStream

java.lang.Object
  org.objectweb.cjdbc.common.stream.CJDBCOutputStream

public class CJDBCOutputStream

extends java.lang.Object

DataOutputStream wrapper used between the controller and the driver.

Author:

Nicolas Modrzyk , Emmanuel Cecchet , CJDBCStream

Field Summary

private long	dateCreated
private java.io.DataOutputStream	output
private java.net.Socket	socket

Constructor Summary

CJDBCOutputStream(java.io.OutputStream out)
Creates a new CJDBCOutputStream from the given input stream.

CJDBCOutputStream(java.net.Socket socket)
Creates a new CJDBCOutputStream object for statistics on sockets

Method Summary

void	close()
void	flush()
long	getDateCreated()
java.net.Socket	getSocket()
void	write(byte[] b)
void	write(byte[] b, int offset, int length)
void	writeBoolean(boolean value)
void	writeDouble(double value)
void	writeFloat(float value)
void	writeInt(int value)
void	writeLong(long value)
void	writeUTF(java.lang.String string) We split the String into 21K-long chunks and encode+send them one after the other.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

output

private java.io.DataOutputStream output

socket

private java.net.Socket socket

dateCreated

private long dateCreated

Constructor Detail

CJDBCOutputStream

public CJDBCOutputStream(java.net.Socket socket)
                  throws java.io.IOException

Creates a new CJDBCOutputStream object for statistics on sockets

Parameters:

socket - socket to monitor

Throws:

java.io.IOException - if an IO error occurs

CJDBCOutputStream

public CJDBCOutputStream(java.io.OutputStream out)

Creates a new CJDBCOutputStream from the given input stream.

Parameters:

out - outputstream to wrap

Method Detail

flush

public void flush()
           throws java.io.IOException

Throws:

java.io.IOException - if an error occurs

See Also:

DataOutputStream.flush()

close

public void close()
           throws java.io.IOException

Throws:

java.io.IOException - if an error occurs

See Also:

FilterOutputStream.close()

writeUTF

public void writeUTF(java.lang.String string)
              throws java.io.IOException

We split the String into 21K-long chunks and encode+send them one after the other. This is because Java's writeUTF() fails when UTFlen is < 64K. UTFlen max is: 2 + 3 * string.length()

Java's writeUTF() is fully specified in DataOutput.writeUTF(java.lang.String) and stable since JDK1.0. Implementation is located in DataOutputStream.writeUTF(java.lang.String, java.io.DataOutput)

At first this looks like a kludge but: (1) On one hand it's almost required anyway to split into chunks (whatever technique we choose) since strings can be infinitely long and we don't want to allocate tons of memory. (2) On the other hand it is hard to find out a String serialization which is both efficient and based upon a standard encoding. Let's briefly look at the alternatives:

• We would like to send java chars as is using DataOutput.writeChars() (since they are just from an UTF-16 subset) but there is no readChars() method (unknown size problem?);
• string.getBytes("UTFXX") is highly portable and flexible but involves a heavy-weight and overkill encoding framework, whereas the encoding of 64K-limited writeUTF() is hard-wired.
• OutputStreamWriter relies on the same framework and is even more complex.
• Maybe some hope from the JNI side? Something like GetStringChars() but in Java?

Parameters:

string - a String to write in UTF form to the stream

Throws:

java.io.IOException - if an error occurs

See Also:

DataOutputStream.writeUTF(java.lang.String)

writeInt

public void writeInt(int value)
              throws java.io.IOException

Parameters:

value - an int value to write to the stream

Throws:

java.io.IOException - if an error occurs

See Also:

DataOutputStream.writeInt(int)

writeLong

public void writeLong(long value)
               throws java.io.IOException

Parameters:

value - a long value to write to the stream

Throws:

java.io.IOException - if an error occurs

See Also:

DataOutputStream.writeLong(long)

writeFloat

public void writeFloat(float value)
                throws java.io.IOException

Parameters:

value - a float value to write to the stream

Throws:

java.io.IOException - if an error occurs

See Also:

DataOutputStream.writeFloat(float)

writeDouble

public void writeDouble(double value)
                 throws java.io.IOException

Parameters:

value - a double value to write to the stream

Throws:

java.io.IOException - if an error occurs

See Also:

DataOutputStream.writeDouble(double)

write

public void write(byte[] b)
           throws java.io.IOException

Parameters:

b - an array of bytes to write to the stream

Throws:

java.io.IOException - if an error occurs

See Also:

FilterOutputStream.write(byte[])

write

public void write(byte[] b,
                  int offset,
                  int length)
           throws java.io.IOException

Throws:

java.io.IOException

See Also:

DataOutputStream.write(byte[], int, int)

writeBoolean

public void writeBoolean(boolean value)
                  throws java.io.IOException

Parameters:

value - a boolean value to write to the stream

Throws:

java.io.IOException - if an error occurs

See Also:

DataOutputStream.writeBoolean(boolean)

getSocket

public java.net.Socket getSocket()

Returns:

Returns the socket.

getDateCreated

public long getDateCreated()

Returns:

Returns the dateCreated.