1/*- 2 * See the file LICENSE for redistribution information. 3 * 4 * Copyright (c) 2002,2008 Oracle. All rights reserved. 5 * 6 * $Id: MultipleNIODataEntry.java,v 1.8 2008/04/02 13:43:38 bschmeck Exp $ 7 */ 8 9package com.sleepycat.db; 10 11import com.sleepycat.db.internal.DbConstants; 12import com.sleepycat.db.internal.DbUtil; 13 14import java.nio.ByteBuffer; 15 16/** 17A DatabaseEntry that holds multiple data items returned by a single 18{@link com.sleepycat.db.Database Database} or {@link com.sleepycat.db.Cursor Cursor} get call. 19*/ 20public class MultipleNIODataEntry extends MultipleEntry { 21 /** 22 Construct an entry with no data. The object must be configured 23 before use with the {@link com.sleepycat.db.DatabaseEntry#setDataNIO DatabaseEntry.setDataNIO} method. 24 */ 25 public MultipleNIODataEntry() { 26 super(null); 27 } 28 29 /** 30 Construct an entry with a given java.nio.ByteBuffer. The offset is 31 set to zero; the size is set to the length of the java.nio.ByteBuffer. 32 <p> 33 @param data 34 java.nio.ByteBuffer wrapped by the entry. 35 */ 36 public MultipleNIODataEntry(final ByteBuffer data) { 37 super(data); 38 } 39 40 /** 41 * Return the bulk retrieval flag and reset the entry position so that the 42 * next set of key/data can be returned. 43 */ 44 /* package */ 45 int getMultiFlag() { 46 pos = 0; 47 return DbConstants.DB_MULTIPLE; 48 } 49 50 /** 51 Get the next data element in the returned set. This method may only 52 be called after a successful call to a {@link com.sleepycat.db.Database Database} or 53 {@link com.sleepycat.db.Cursor Cursor} get method with this object as the data parameter. 54 <p> 55 When used with the Queue and Recno access methods, 56 <code>data.getData()<code> will return <code>null</code> for deleted 57 records. 58 <p> 59 @param data 60 an entry that is set to refer to the next data element in the returned 61 set. 62 <p> 63 @return 64 indicates whether a value was found. A return of <code>false</code> 65 indicates that the end of the set was reached. 66 */ 67 public boolean next(final DatabaseEntry data) { 68 byte[] intarr; 69 int saveoffset; 70 if (pos == 0) 71 pos = ulen - INT32SZ; 72 73 // pull the offsets out of the ByteBuffer. 74 if(this.data_nio.capacity() < 8) 75 return false; 76 intarr = new byte[8]; 77 saveoffset = this.data_nio.position(); 78 this.data_nio.position(pos - INT32SZ); 79 this.data_nio.get(intarr, 0, 8); 80 this.data_nio.position(saveoffset); 81 82 final int dataoff = DbUtil.array2int(intarr, 4); 83 84 // crack out the data offset and length. 85 if (dataoff < 0) { 86 return (false); 87 } 88 89 final int datasz = DbUtil.array2int(intarr, 0); 90 91 // move the position to one before the last offset read. 92 pos -= INT32SZ*2; 93 94 data.setDataNIO(this.data_nio); 95 data.setSize(datasz); 96 data.setOffset(dataoff); 97 98 return (true); 99 } 100} 101