Package org.apache.hadoop.io

Class OutputBuffer

java.lang.Object

java.io.OutputStream

java.io.FilterOutputStream

org.apache.hadoop.io.OutputBuffer

All Implemented Interfaces:

java.io.Closeable, java.io.Flushable, java.lang.AutoCloseable

@LimitedPrivate({"HDFS","MapReduce"})
@Unstable
public class OutputBuffer
extends java.io.FilterOutputStream

A reusable OutputStream implementation that writes to an in-memory buffer.

This saves memory over creating a new OutputStream and ByteArrayOutputStream each time data is written.

Typical usage is something like the following:

 OutputBuffer buffer = new OutputBuffer();
 while (... loop condition ...) {
   buffer.reset();
   ... write buffer using OutputStream methods ...
   byte[] data = buffer.getData();
   int dataLength = buffer.getLength();
   ... write data to its ultimate destination ...
 }
 

See Also:

DataOutputBuffer, InputBuffer

Field Summary

Fields inherited from class java.io.FilterOutputStream

out

Constructor Summary

Constructors

Constructor	Description
OutputBuffer()	Constructs a new empty buffer.

Method Summary

Modifier and Type	Method	Description
byte[]	getData()	Returns the current contents of the buffer.
int	getLength()	Returns the length of the valid data currently in the buffer.
OutputBuffer	reset()
void	write(java.io.InputStream in, int length)	Writes bytes from a InputStream directly into the buffer.

Methods inherited from class java.io.FilterOutputStream

close, flush, write, write, write

Methods inherited from class java.io.OutputStream

nullOutputStream

Methods inherited from class java.lang.Object

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

Constructor Detail

OutputBuffer

public OutputBuffer()

Constructs a new empty buffer.

Method Detail

getData

public byte[] getData()

Returns the current contents of the buffer. Data is only valid to getLength().

Returns:

the current contents of the buffer.

getLength

public int getLength()

Returns the length of the valid data currently in the buffer.

Returns:

the length of the valid data currently in the buffer.

reset

public OutputBuffer reset()

Returns:

Resets the buffer to empty.

write

public void write(java.io.InputStream in,
                  int length)
           throws java.io.IOException

Writes bytes from a InputStream directly into the buffer.

Parameters:

in - input in.

length - input length.

Throws:

java.io.IOException - raised on errors performing I/O.