com.sleepycat.bdb
Class DataCursor

java.lang.Object
  |
  +--com.sleepycat.bdb.DataCursor

public final class DataCursor

extends Object

(internal) Represents a Berkeley DB cursor and adds support for indices, bindings and key ranges.

NOTE: This classes is internal and may be changed incompatibly or deleted in the future. It is public only so it may be used by subpackages.

This class operates on a view and takes care of reading and updating indices, calling bindings, constraining access to a key range, etc.

Constructor Summary

DataCursor(DataCursor other)
Clones a cursor preserving the current position.

DataCursor(DataView view, boolean writeAllowed)
Creates a cursor for a given view.

DataCursor(DataView view, boolean writeAllowed, Object singleKey)
Creates a cursor for a given view and single key range.

DataCursor(DataView view, boolean writeAllowed, Object beginKey, boolean beginInclusive, Object endKey, boolean endInclusive)
Creates a cursor for a given view and key range.

Method Summary

void	close() Closes a cursor.
int	count() Return the number of duplicates for the current key.
int	delete() Perform an arbitrary database 'delete' operation.
int	find(Object value, boolean findFirst) Find the given value, using DB_GET_BOTH if possible, or a sequential search otherwise.
int	get(Object key, Object value, int flag, boolean lockForWrite) Perform a database 'get' using the given key and value.
Object	getCurrentKey() Returns the key object for the last record read.
int	getCurrentRecordNumber() Returns the record number for the last record read.
Object	getCurrentValue() Returns the value object for the last record read.
DataView	getView() Returns the view for this cursor, as specified to the constructor.
boolean	hasRecNumAccess() Returns whether record number access is allowed.
boolean	isWriteAllowed() Returns whether write is allowed for this cursor, as specified to the constructor.
int	put(Object key, Object value, int flag, Object[] oldValue) Perform an arbitrary database 'put' operation, optionally returning the previous value.
int	put(Object key, Object value, int flag, Object[] oldValue, boolean useCurrentKey) Perform an arbitrary database 'put' operation, optionally using the current key instead of the key parameter.

Methods inherited from class java.lang.Object

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

Constructor Detail

DataCursor

public DataCursor(DataView view,
                  boolean writeAllowed)
           throws DbException,
                  IOException

Creates a cursor for a given view.

Parameters:

view - the database view traversed by the cursor.

writeAllowed - whether the cursor can be used for writing.

Throws:

DbException - if a database problem occurs.

IOException - if an IO problem occurs.

DataCursor

public DataCursor(DataView view,
                  boolean writeAllowed,
                  Object singleKey)
           throws DbException,
                  IOException

Creates a cursor for a given view and single key range.

Parameters:

view - the database view traversed by the cursor.

writeAllowed - whether the cursor can be used for writing.

singleKey - the single key value.

Throws:

DbException - if a database problem occurs.

IOException - if an IO problem occurs.

DataCursor

public DataCursor(DataView view,
                  boolean writeAllowed,
                  Object beginKey,
                  boolean beginInclusive,
                  Object endKey,
                  boolean endInclusive)
           throws DbException,
                  IOException

Creates a cursor for a given view and key range.

Parameters:

view - the database view traversed by the cursor.

writeAllowed - whether the cursor can be used for writing.

beginKey - the lower bound.

beginInclusive - whether the lower bound is inclusive.

endKey - the upper bound.

endInclusive - whether the upper bound is inclusive.

Throws:

DbException - if a database problem occurs.

IOException - if an IO problem occurs.

DataCursor

public DataCursor(DataCursor other)
           throws DbException,
                  IOException

Clones a cursor preserving the current position.

Parameters:

other - the cursor to clone.

Throws:

DbException - if a database problem occurs.

IOException - if an IO problem occurs.

Method Detail

close

public void close()
           throws DbException,
                  IOException

Closes a cursor.

Throws:

DbException - if a database problem occurs.

IOException - if an IO problem occurs.

getView

public DataView getView()

Returns the view for this cursor, as specified to the constructor.

Returns:

the view.

isWriteAllowed

public boolean isWriteAllowed()

Returns whether write is allowed for this cursor, as specified to the constructor.

Returns:

whether write is allowed.

getCurrentKey

public Object getCurrentKey()
                     throws DbException,
                            IOException

Returns the key object for the last record read.

Returns:

the current key object.

Throws:

DbException - if a database problem occurs.

IOException - if an IO problem occurs.

getCurrentValue

public Object getCurrentValue()
                       throws DbException,
                              IOException

Returns the value object for the last record read.

Returns:

the current value object.

Throws:

DbException - if a database problem occurs.

IOException - if an IO problem occurs.

hasRecNumAccess

public boolean hasRecNumAccess()

Returns whether record number access is allowed.

Returns:

whether record number access is allowed.

getCurrentRecordNumber

public int getCurrentRecordNumber()
                           throws DbException,
                                  IOException

Returns the record number for the last record read.

Returns:

the last read record number.

Throws:

DbException - if a database problem occurs.

IOException - if an IO problem occurs.

get

public int get(Object key,
               Object value,
               int flag,
               boolean lockForWrite)
        throws DbException,
               IOException

Perform a database 'get' using the given key and value.

Parameters:

key - the key or null if none is required by the flag.

value - the value or null if none is required by the flag.

flag - a single flag value appropriate for cursor get.

lockForWrite - whether to set the RMW flag.

Returns:

an error or zero for success.

Throws:

DbException - if a database problem occurs.

IOException - if an IO problem occurs.

find

public int find(Object value,
                boolean findFirst)
         throws DbException,
                IOException

Find the given value, using DB_GET_BOTH if possible, or a sequential search otherwise.

Parameters:

value - the value to search for among duplicates at the current position.

findFirst - whether to find the first or last value.

Returns:

an error or zero for success.

Throws:

DbException - if a database problem occurs.

IOException - if an IO problem occurs.

count

public int count()
          throws DbException,
                 IOException

Return the number of duplicates for the current key.

Returns:

the number of duplicates.

Throws:

DbException - if a database problem occurs.

IOException - if an IO problem occurs.

put

public int put(Object key,
               Object value,
               int flag,
               Object[] oldValue)
        throws DbException,
               IOException

Perform an arbitrary database 'put' operation, optionally returning the previous value.

Parameters:

key - the key to put.

value - the value to put.

flag - a single flag value appropriate for cursor put.

oldValue - holds the old value, or null if the old value should not be returned.

Returns:

an error or zero for success.

Throws:

DbException - if a database problem occurs.

IOException - if an IO problem occurs.

put

public int put(Object key,
               Object value,
               int flag,
               Object[] oldValue,
               boolean useCurrentKey)
        throws DbException,
               IOException

Perform an arbitrary database 'put' operation, optionally using the current key instead of the key parameter.

Parameters:

key - the key to put.

value - the value to put.

flag - a single flag value appropriate for cursor put.

oldValue - holds the old value, or null if the old value should not be returned.

useCurrentKey - is true to use the current key rather than the key parameter.

Returns:

an error or zero for success.

Throws:

DbException - if a database problem occurs.

IOException - if an IO problem occurs.

delete

public int delete()
           throws DbException,
                  IOException

Perform an arbitrary database 'delete' operation.

Returns:

an error or zero for success.

Throws:

DbException - if a database problem occurs.

IOException - if an IO problem occurs.