org.apache.hadoop.io
Class DataOutputBuffer

java.lang.Object
  java.io.OutputStream
      java.io.FilterOutputStream
          java.io.DataOutputStream
              org.apache.hadoop.io.DataOutputBuffer

All Implemented Interfaces:

Closeable, DataOutput, Flushable

public class DataOutputBuffer
extends DataOutputStream

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

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

Typical usage is something like the following:

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

Field Summary

Fields inherited from class java.io.DataOutputStream

written

Fields inherited from class java.io.FilterOutputStream

out

Constructor Summary

DataOutputBuffer()
Constructs a new empty buffer.

DataOutputBuffer(int size)

Method Summary

byte[]	getData() Returns the current contents of the buffer.
int	getLength() Returns the length of the valid data currently in the buffer.
DataOutputBuffer	reset() Resets the buffer to empty.
void	write(DataInput in, int length) Writes bytes from a DataInput directly into the buffer.
void	writeTo(OutputStream out) Write to a file stream

Methods inherited from class java.io.DataOutputStream

flush, size, write, write, writeBoolean, writeByte, writeBytes, writeChar, writeChars, writeDouble, writeFloat, writeInt, writeLong, writeShort, writeUTF

Methods inherited from class java.io.FilterOutputStream

close, write

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.io.DataOutput

write

Constructor Detail

DataOutputBuffer

public DataOutputBuffer()

Constructs a new empty buffer.

DataOutputBuffer

public DataOutputBuffer(int size)

Method Detail

getData

public byte[] getData()

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

getLength

public int getLength()

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

reset

public DataOutputBuffer reset()

Resets the buffer to empty.

write

public void write(DataInput in,
                  int length)
           throws IOException

Writes bytes from a DataInput directly into the buffer.

Throws:

IOException

writeTo

public void writeTo(OutputStream out)
             throws IOException

Write to a file stream

Throws:

IOException