ca.idms.io
Class TraceBufferOutputStream

java.lang.Object
  java.io.OutputStream
      java.io.ByteArrayOutputStream
          ca.idms.io.TraceBufferOutputStream

All Implemented Interfaces:

java.io.Closeable, java.io.Flushable

public class TraceBufferOutputStream
extends java.io.ByteArrayOutputStream

A TraceBufferOutputStream extends ByteArrayOutputStream to provide tracing and buffering of an underlying OutputStream.

Data written to the stream is collected in a buffer, which grows as needed. When the flush method is called, the contents of the buffer are displayed in the trace stream, if enabled, and written to the output stream. The ByteArrayInputStream methods are used to write data to the buffer.

This class also provides methods to optimize buffering by explicitly setting the size buffer and allowing access to the buffer without copying it.

Version:

2.00, 12/14/99

Author:

Dave Ross

See Also:

TraceObject, ByteArrayOutputStream

Field Summary

protected java.io.OutputStream	out The actual output stream.
protected TraceObject	trace The trace control object.

Fields inherited from class java.io.ByteArrayOutputStream

buf, count

Constructor Summary

TraceBufferOutputStream(TraceObject trace, int len)
Creates a buffered trace stream with no underlying output stream.

TraceBufferOutputStream(TraceObject trace, java.io.OutputStream out)
Creates a buffered trace stream with a default buffer size.

TraceBufferOutputStream(TraceObject trace, java.io.OutputStream out, int len)
Creates a buffered trace stream to write data to the specified underlying output stream.

Method Summary

void	flush() Flushes this output stream and forces any buffered output bytes to be written out to the stream.
byte[]	getBuffer() Gets a reference to the buffer.
int	getCount() Gets the number of valid bytes in the buffer.
void	setBuffer(byte[] buf, int len) Sets the buffer.
void	setCount(int len) Set the number of valid bytes in the buffer.
void	setSize(int len) Sets the size of the buffer.
void	snap(boolean f) Displays the contents of this buffer if tracing is enabled.

Methods inherited from class java.io.ByteArrayOutputStream

close, reset, size, toByteArray, toString, toString, toString, write, write, writeTo

Methods inherited from class java.io.OutputStream

write

Methods inherited from class java.lang.Object

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

Field Detail

trace

protected TraceObject trace

The trace control object.

out

protected java.io.OutputStream out

The actual output stream.

Constructor Detail

TraceBufferOutputStream

public TraceBufferOutputStream(TraceObject trace,
                               java.io.OutputStream out,
                               int len)

Creates a buffered trace stream to write data to the specified underlying output stream.

Parameters:

trace - the trace control object

out - the underlying output stream.

len - the initial size of the buffer.

TraceBufferOutputStream

public TraceBufferOutputStream(TraceObject trace,
                               java.io.OutputStream out)

Creates a buffered trace stream with a default buffer size.

Parameters:

trace - the trace control object

out - the underlying output stream.

TraceBufferOutputStream

public TraceBufferOutputStream(TraceObject trace,
                               int len)

Creates a buffered trace stream with no underlying output stream.

Parameters:

trace - the trace control object

len - the initial size of the buffer.

Method Detail

setSize

public void setSize(int len)

Sets the size of the buffer. This method allows optimization of the buffer size. The previous contents of the buffer are released.

Parameters:

len - new buffer size.

getBuffer

public byte[] getBuffer()

Gets a reference to the buffer. In contrast to ByteArrayOutputStream.toByteArray(), this method returns a reference to the actual byte array, rather than a copy of the array contents.

Note that subsequent writes to this stream can change the contents of the buffer, and changing the contents of the buffer can corrupt the state of the stream.

Returns:

buf.

setBuffer

public void setBuffer(byte[] buf,
                      int len)

Sets the buffer. This method allows an existing byte array to be inserted into the output stream. The previous contents of the buffer are released.

Parameters:

buf - the new buffer contents

len - the length used in the array

getCount

public int getCount()

Gets the number of valid bytes in the buffer. This is equivalent to ByteArrayOutputStream.size(), named to be consistent with TraceBufferInputStream.

Returns:

count

setCount

public void setCount(int len)

Set the number of valid bytes in the buffer. This can be used to reset the position in the buffer to overwrite it's contents.

Parameters:

len - new count, ignored if out of range

See Also:

getCount()

snap

public void snap(boolean f)

Displays the contents of this buffer if tracing is enabled. Enabled by TraceObject.trace() and TraceObject.snapBytes.

See Also:

TraceObject

flush

public void flush()
           throws java.io.IOException

Flushes this output stream and forces any buffered output bytes to be written out to the stream.

The buffer is displayed in the log if tracing bytes is enabled. This method will throw a NullPointerException if there is no underlying output stream.

Specified by:

flush in interface java.io.Flushable

Overrides:

flush in class java.io.OutputStream

Throws:

java.io.IOException - if an I/O error occurs.

See Also:

TraceObject