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/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 2013, 2015 Oracle and/or its affiliates. All rights reserved.
*
* $Id$
*/
package com.sleepycat.db;
import com.sleepycat.db.internal.DbConstants;
import com.sleepycat.db.internal.DbStream;
/**
A database stream. The database stream is used to access the blob.
<p>
Once the database stream close method has been called, the handle may not
be accessed again.
<p>
To obtain a database stream with default attributes:
<blockquote><pre>
DatabaseStream dbs = myCursor.openDatabaseStream(null);
</pre></blockquote>
To customize the attributes of a database stream,
use a DatabaseStreamConfig object.
<blockquote><pre>
DatabaseStreamConfig config = new DatabaseStreamConfig();
config.setReadOnly(true);
DatabaseStream dbs = myCursor.openDatabaseStream(config);
</pre></blockquote>
*/
public class DatabaseStream {
/* package */ DbStream dbs;
/* package */ Cursor cursor;
/* package */ DatabaseStreamConfig config;
protected DatabaseStream(
final Cursor cursor, final DatabaseStreamConfig config) {
this.cursor = cursor;
this.config = config;
}
DatabaseStream(final Cursor cursor,
final DbStream dbs, final DatabaseStreamConfig config)
throws DatabaseException {
this.cursor = cursor;
this.dbs = dbs;
this.config = config;
}
/**
Discard the database stream.
<p>
After the close method has been called, you cannot use the database stream
handle again.
<p>
It is recommended to always close all database stream handles immediately
after their use to release resources.
<p>
@throws DatabaseException if a failure occurs.
*/
public synchronized void close()
throws DatabaseException {
if (dbs != null) {
try {
dbs.close(0);
} finally {
dbs = null;
}
}
}
/**
Return this database stream configuration.
<p>
@return
This database stream configuration.
<p>
@throws DatabaseException if a failure occurs.
*/
public DatabaseStreamConfig getConfig() {
return config;
}
/**
Return the {@link com.sleepycat.db.Cursor Cursor} handle associated
with this database stream.
<p>
@return
The cursor handle associated with this database stream.
*/
public Cursor getCursor() {
return cursor;
}
/**
Read from the blob accessed by this database stream.
<p>
@throws IllegalArgumentException if a failure occurs.
<p>
@param data the data read from the blob
returned as output. Its byte array does not need to be initialized by the
caller.
<p>
@param offset the position in bytes in the blob where the reading starts.
<p>
@param size the number of bytes to read.
<p>
@return {@link com.sleepycat.db.OperationStatus#SUCCESS OperationStatus.SUCCESS}
if the operation succeeds.
<p>
@throws IllegalArgumentException if the operation fails.
<p>
@throws DatabaseException if a failure occurs.
*/
public OperationStatus read(final DatabaseEntry data, long offset, int size)
throws DatabaseException, IllegalArgumentException {
return OperationStatus.fromInt(
dbs.read(data, offset, size, 0));
}
/**
Return the size in bytes of the blob accessed by the database stream.
<p>
@return
The size in bytes of the blob accessed by the database stream.
<p>
@throws DatabaseException if a failure occurs.
*/
public long size()
throws DatabaseException {
return dbs.size(0);
}
/**
Write to the blob accessed by the database stream.
<p>
@param data the data {@link com.sleepycat.db.DatabaseEntry DatabaseEntry}
to write into the blob.
<p>
@param offset the position in bytes in the blob where the writing starts.
<p>
@return {@link com.sleepycat.db.OperationStatus#SUCCESS OperationStatus.SUCCESS}
if the operation succeeds.
<p>
@throws IllegalArgumentException if the operation fails.
<p>
@throws DatabaseException if a failure occurs.
*/
public OperationStatus write(final DatabaseEntry data, long offset)
throws DatabaseException, IllegalArgumentException {
return OperationStatus.fromInt(dbs.write(data, offset, 0));
}
}
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