org.apache.lucene.store
Class DataInput

java.lang.Object
  extended by org.apache.lucene.store.DataInput
All Implemented Interfaces:
Cloneable
Direct Known Subclasses:
ByteArrayDataInput, IndexInput, InputStreamDataInput

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


Copyright © 2000-2011 Apache Software Foundation. All Rights Reserved.