Package org.apache.hadoop.io

Class DataInputBuffer

java.lang.Object

java.io.InputStream

java.io.FilterInputStream

java.io.DataInputStream

org.apache.hadoop.io.DataInputBuffer

All Implemented Interfaces:

Closeable, DataInput, AutoCloseable

@LimitedPrivate({"HDFS","MapReduce"})
@Unstable
public class DataInputBuffer
extends DataInputStream

A reusable DataInput implementation that reads from an in-memory buffer.

This saves memory over creating a new DataInputStream and ByteArrayInputStream each time data is read.

Typical usage is something like the following:

 DataInputBuffer buffer = new DataInputBuffer();
 while (... loop condition ...) {
   byte[] data = ... get data ...;
   int dataLength = ... get data length ...;
   buffer.reset(data, dataLength);
   ... read buffer using DataInput methods ...
 }
 

Field Summary

Fields inherited from class java.io.FilterInputStream

in

Constructor Summary

Constructors

Constructor	Description
DataInputBuffer()	Constructs a new empty buffer.

Method Summary

Modifier and Type	Method	Description
byte[]	getData()
int	getLength()	Returns the index one greater than the last valid character in the input stream buffer.
int	getPosition()	Returns the current position in the input.
void	reset(byte[] input, int length)	Resets the data that the buffer reads.
void	reset(byte[] input, int start, int length)	Resets the data that the buffer reads.

Methods inherited from class java.io.DataInputStream

read, read, readBoolean, readByte, readChar, readDouble, readFloat, readFully, readFully, readInt, readLine, readLong, readShort, readUnsignedByte, readUnsignedShort, readUTF, readUTF, skipBytes

Methods inherited from class java.io.FilterInputStream

available, close, mark, markSupported, read, reset, skip

Methods inherited from class java.io.InputStream

nullInputStream, readAllBytes, readNBytes, readNBytes, skipNBytes, transferTo

Methods inherited from class java.lang.Object

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

Constructor Details

DataInputBuffer

public DataInputBuffer()

Constructs a new empty buffer.

Method Details

reset

public void reset(byte[] input,
 int length)

Resets the data that the buffer reads.

Parameters:

input - input.

length - length.

reset

public void reset(byte[] input,
 int start,
 int length)

Resets the data that the buffer reads.

Parameters:

input - input.

start - start.

length - length.

getData

public byte[] getData()

getPosition

public int getPosition()

Returns the current position in the input.

Returns:

position.

getLength

public int getLength()

Returns the index one greater than the last valid character in the input stream buffer.

Returns:

length.