org.apache.lucene.store
Class IndexInput

java.lang.Object
  extended by org.apache.lucene.store.DataInput
      extended by org.apache.lucene.store.IndexInput
All Implemented Interfaces:
Closeable, Cloneable
Direct Known Subclasses:
BufferedIndexInput, ChecksumIndexInput, RAMInputStream

public abstract class IndexInput
extends DataInput
implements Cloneable, Closeable

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

IndexInput may only be used from one thread, because it is not thread safe (it keeps internal state like file position). To allow multithreaded use, every IndexInput instance must be cloned before used in another thread. Subclasses must therefore implement clone(), returning a new IndexInput which operates on the same underlying resource, but positioned independently. Lucene never closes cloned IndexInputs, it will only do this on the original one. The original instance must take care that cloned instances throw AlreadyClosedException when the original one is closed.

See Also:
Directory

Constructor Summary
protected IndexInput(String resourceDescription)
          resourceDescription should be a non-null, opaque string describing this resource; it's returned from toString().
 
Method Summary
 IndexInput clone()
          Returns a clone of this stream.
abstract  void close()
          Closes the stream to further 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  void seek(long pos)
          Sets current position in this file, where the next read will occur.
 String toString()
           
 
Methods inherited from class org.apache.lucene.store.DataInput
readByte, readBytes, readBytes, readInt, readLong, readShort, readString, readStringSet, readStringStringMap, readVInt, readVLong
 
Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

IndexInput

protected IndexInput(String resourceDescription)
resourceDescription should be a non-null, opaque string describing this resource; it's returned from toString().

Method Detail

close

public abstract void close()
                    throws IOException
Closes the stream to further operations.

Specified by:
close in interface Closeable
Throws:
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 IOException
Sets current position in this file, where the next read will occur.

Throws:
IOException
See Also:
getFilePointer()

length

public abstract long length()
The number of bytes in the file.


toString

public String toString()
Overrides:
toString in class Object

clone

public IndexInput 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.

Warning: Lucene never closes cloned IndexInputs, it will only do this on the original one. The original instance must take care that cloned instances throw AlreadyClosedException when the original one is closed.

Overrides:
clone in class DataInput


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