org.apache.lucene.store
Class DataInput

java.lang.Object
  org.apache.lucene.store.DataInput

All Implemented Interfaces:

Cloneable

Direct Known Subclasses:

ByteArrayDataInput, FST.BytesReader, IndexInput, InputStreamDataInput, PagedBytes.PagedBytesDataInput

public abstract class DataInput
extends Object
implements Cloneable

Abstract base class for performing read operations of Lucene's low-level data types.

Constructor Summary

DataInput()

Method Summary

Object	clone() Returns a clone of this stream.
abstract byte	readByte() Reads and returns a single byte.
abstract void	readBytes(byte[] b, int offset, int len) Reads a specified number of bytes into an array at the specified offset.
void	readBytes(byte[] b, int offset, int len, boolean useBuffer) Reads a specified number of bytes into an array at the specified offset with control over whether the read should be buffered (callers who have their own buffer should pass in "false" for useBuffer).
void	readChars(char[] buffer, int start, int length) Deprecated. -- please use readString or readBytes instead, and construct the string from those utf8 bytes
int	readInt() Reads four bytes and returns an int.
long	readLong() Reads eight bytes and returns a long.
short	readShort() Reads two bytes and returns a short.
String	readString() Reads a string.
Map<String,String>	readStringStringMap()
int	readVInt() Reads an int stored in variable-length format.
long	readVLong() Reads a long stored in variable-length format.
void	setModifiedUTF8StringsMode() Call this if readString should read characters stored in the old modified UTF8 format (length in java chars and java's modified UTF8 encoding).

Methods inherited from class java.lang.Object

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

Constructor Detail

DataInput

public DataInput()

Method Detail

setModifiedUTF8StringsMode

public void setModifiedUTF8StringsMode()

Call this if readString should read characters stored in the old modified UTF8 format (length in java chars and java's modified UTF8 encoding). This is used for indices written pre-2.4 See LUCENE-510 for details.

readByte

public abstract byte readByte()
                       throws IOException

Reads and returns a single byte.

Throws:

IOException

See Also:

DataOutput.writeByte(byte)

readBytes

public abstract void readBytes(byte[] b,
                               int offset,
                               int len)
                        throws IOException

Reads a specified number of bytes into an array at the specified offset.

Parameters:

b - the array to read bytes into

offset - the offset in the array to start storing bytes

len - the number of bytes to read

Throws:

IOException

See Also:

DataOutput.writeBytes(byte[],int)

readBytes

public void readBytes(byte[] b,
                      int offset,
                      int len,
                      boolean useBuffer)
               throws IOException

Reads a specified number of bytes into an array at the specified offset with control over whether the read should be buffered (callers who have their own buffer should pass in "false" for useBuffer). Currently only BufferedIndexInput respects this parameter.

Parameters:

b - the array to read bytes into

offset - the offset in the array to start storing bytes

len - the number of bytes to read

useBuffer - set to false if the caller will handle buffering.

Throws:

IOException

See Also:

DataOutput.writeBytes(byte[],int)

readShort

public short readShort()
                throws IOException

Reads two bytes and returns a short.

Throws:

IOException

See Also:

DataOutput.writeByte(byte)

readInt

public int readInt()
            throws IOException

Reads four bytes and returns an int.

Throws:

IOException

See Also:

DataOutput.writeInt(int)

readVInt

public int readVInt()
             throws IOException

Reads an int stored in variable-length format. Reads between one and five bytes. Smaller values take fewer bytes. Negative numbers are not supported.

Throws:

IOException

See Also:

DataOutput.writeVInt(int)

readLong

public long readLong()
              throws IOException

Reads eight bytes and returns a long.

Throws:

IOException

See Also:

DataOutput.writeLong(long)

readVLong

public long readVLong()
               throws IOException

Reads a long stored in variable-length format. Reads between one and nine bytes. Smaller values take fewer bytes. Negative numbers are not supported.

Throws:

IOException

readString

public String readString()
                  throws IOException

Reads a string.

Throws:

IOException

See Also:

DataOutput.writeString(String)

readChars

@Deprecated
public void readChars(char[] buffer,
                                 int start,
                                 int length)
               throws IOException

Deprecated. -- please use readString or readBytes instead, and construct the string from those utf8 bytes

Reads Lucene's old "modified UTF-8" encoded characters into an array.

Parameters:

buffer - the array to read characters into

start - the offset in the array to start storing characters

length - the number of characters to read

Throws:

IOException

See Also:

DataOutput.writeChars(String,int,int)

clone

public Object clone()

Returns a clone of this stream.

Clones of a stream access the same data, and are positioned at the same point as the stream they were cloned from.

Expert: Subclasses must ensure that clones may be positioned at different points in the input from each other and from the stream they were cloned from.

Overrides:

clone in class Object

readStringStringMap

public Map<String,String> readStringStringMap()
                                       throws IOException

Throws:

IOException