org.apache.lucene.store

Class IndexInput

java.lang.Object

org.apache.lucene.store.IndexInput

All Implemented Interfaces:

java.lang.Cloneable

Direct Known Subclasses:

BufferedIndexInput

public abstract class IndexInput
extends java.lang.Object
implements java.lang.Cloneable

Abstract base class for input from a file in a Directory. A random-access input stream. Used for all Lucene index input operations.

See Also:

Directory

Constructor Summary

Constructors

Constructor and Description
IndexInput()

Method Summary

Modifier and Type	Method and Description
java.lang.Object	clone() Returns a clone of this stream.
abstract void	close() Closes the stream to futher operations.
abstract long	getFilePointer() Returns the current position in this file, where the next read will occur.
abstract long	length() The number of bytes in the file.
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) Reads UTF-8 encoded characters into an array.
int	readInt() Reads four bytes and returns an int.
long	readLong() Reads eight bytes and returns a long.
java.lang.String	readString() Reads a string.
int	readVInt() Reads an int stored in variable-length format.
long	readVLong() Reads a long stored in variable-length format.
abstract void	seek(long pos) Sets current position in this file, where the next read will occur.
void	skipChars(int length) Expert Similar to readChars(char[], int, int) but does not do any conversion operations on the bytes it is reading in.

Methods inherited from class java.lang.Object

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

Constructor Detail

IndexInput

public IndexInput()

Method Detail

readByte

public abstract byte readByte()
                       throws java.io.IOException

Reads and returns a single byte.

Throws:

java.io.IOException

See Also:

IndexOutput.writeByte(byte)

readBytes

public abstract void readBytes(byte[] b,
                               int offset,
                               int len)
                        throws java.io.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:

java.io.IOException

See Also:

IndexOutput.writeBytes(byte[],int)

readBytes

public void readBytes(byte[] b,
                      int offset,
                      int len,
                      boolean useBuffer)
               throws java.io.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:

java.io.IOException

See Also:

IndexOutput.writeBytes(byte[],int)

readInt

public int readInt()
            throws java.io.IOException

Reads four bytes and returns an int.

Throws:

java.io.IOException

See Also:

IndexOutput.writeInt(int)

readVInt

public int readVInt()
             throws java.io.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:

java.io.IOException

See Also:

IndexOutput.writeVInt(int)

readLong

public long readLong()
              throws java.io.IOException

Reads eight bytes and returns a long.

Throws:

java.io.IOException

See Also:

IndexOutput.writeLong(long)

readVLong

public long readVLong()
               throws java.io.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:

java.io.IOException

readString

public java.lang.String readString()
                            throws java.io.IOException

Reads a string.

Throws:

java.io.IOException

See Also:

IndexOutput.writeString(String)

readChars

public void readChars(char[] buffer,
                      int start,
                      int length)
               throws java.io.IOException

Reads 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:

java.io.IOException

See Also:

IndexOutput.writeChars(String,int,int)

skipChars

public void skipChars(int length)
               throws java.io.IOException

Expert Similar to readChars(char[], int, int) but does not do any conversion operations on the bytes it is reading in. It still has to invoke readByte() just as readChars(char[], int, int) does, but it does not need a buffer to store anything and it does not have to do any of the bitwise operations, since we don't actually care what is in the byte except to determine how many more bytes to read

Parameters:

length - The number of chars to read

Throws:

java.io.IOException

close

public abstract void close()
                    throws java.io.IOException

Closes the stream to futher operations.

Throws:

java.io.IOException

getFilePointer

public abstract long getFilePointer()

Returns the current position in this file, where the next read will occur.

See Also:

seek(long)

seek

public abstract void seek(long pos)
                   throws java.io.IOException

Sets current position in this file, where the next read will occur.

Throws:

java.io.IOException

See Also:

getFilePointer()

length

public abstract long length()

The number of bytes in the file.

clone

public java.lang.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 java.lang.Object