001/* 002 * Copyright 2009-2014 UnboundID Corp. 003 * All Rights Reserved. 004 */ 005/* 006 * Copyright (C) 2009-2014 UnboundID Corp. 007 * 008 * This program is free software; you can redistribute it and/or modify 009 * it under the terms of the GNU General Public License (GPLv2 only) 010 * or the terms of the GNU Lesser General Public License (LGPLv2.1 only) 011 * as published by the Free Software Foundation. 012 * 013 * This program is distributed in the hope that it will be useful, 014 * but WITHOUT ANY WARRANTY; without even the implied warranty of 015 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 016 * GNU General Public License for more details. 017 * 018 * You should have received a copy of the GNU General Public License 019 * along with this program; if not, see <http://www.gnu.org/licenses>. 020 */ 021package com.unboundid.ldap.sdk; 022 023 024 025import com.unboundid.util.NotExtensible; 026import com.unboundid.util.ThreadSafety; 027import com.unboundid.util.ThreadSafetyLevel; 028 029 030 031/** 032 * This class defines an API that may be implemented by a class that provides 033 * access to a sequence of entries, one entry at a time (e.g., entries read from 034 * an LDIF file, or returned as part of an LDAP search). It provides a 035 * convenient way to operate on a set of entries without regard for the source 036 * of those entries. Implementations currently available include the 037 * {@link LDAPEntrySource} class, which can be used to iterate across entries 038 * returned from a directory server in response to a search request, and the 039 * {@link com.unboundid.ldif.LDIFEntrySource} class, which can be used to 040 * iterate across entries in an LDIF file. 041 * <BR><BR> 042 * Note that the {@link #close} method MUST be called if the entry source is to 043 * be discarded before guaranteeing that all entries have been read. The 044 * {@code close} method may be called after all entries have been read, but it 045 * is not required. All entry source implementations MUST ensure that all 046 * resources are properly released if the caller has read through all entries, 047 * or if an error occurs that prevents the caller from continuing to read 048 * through the entries (i.e., if {@link #nextEntry} throws an 049 * {@link EntrySourceException} and the 050 * {@link EntrySourceException#mayContinueReading()} method returns 051 * {@code false}). 052 * <BR><BR> 053 * <H2>Example</H2> 054 * The following example demonstrates the process that may be used for iterating 055 * across the entries provided by an entry source: 056 * <PRE> 057 * LDIFReader ldifReader = new LDIFReader(ldifFilePath); 058 * EntrySource entrySource = new LDIFEntrySource(ldifReader); 059 * 060 * int entriesRead = 0; 061 * int exceptionsCaught = 0; 062 * try 063 * { 064 * while (true) 065 * { 066 * try 067 * { 068 * Entry entry = entrySource.nextEntry(); 069 * if (entry == null) 070 * { 071 * // There are no more entries to be read. 072 * break; 073 * } 074 * else 075 * { 076 * // Do something with the entry here. 077 * entriesRead++; 078 * } 079 * } 080 * catch (EntrySourceException e) 081 * { 082 * // Some kind of problem was encountered (e.g., a malformed entry 083 * // found in an LDIF file, or a referral returned from a directory). 084 * // See if we can continue reading entries. 085 * exceptionsCaught++; 086 * if (! e.mayContinueReading()) 087 * { 088 * break; 089 * } 090 * } 091 * } 092 * } 093 * finally 094 * { 095 * entrySource.close(); 096 * } 097 * </PRE> 098 */ 099@NotExtensible() 100@ThreadSafety(level=ThreadSafetyLevel.INTERFACE_NOT_THREADSAFE) 101public abstract class EntrySource 102{ 103 /** 104 * Retrieves the next entry from the entry source, if there is at least one 105 * remaining entry. This method may block if no entries are immediately 106 * available. 107 * 108 * @return The next entry from the entry source, or {@code null} if there are 109 * no more entries to retrieve.. 110 * 111 * @throws EntrySourceException If a problem occurs while attempting to read 112 * the next entry from the entry source. 113 */ 114 public abstract Entry nextEntry() 115 throws EntrySourceException; 116 117 118 119 /** 120 * Indicates that this entry source will no longer be needed and any resources 121 * associated with it may be closed. This method MUST be called if the entry 122 * source is no longer needed before all entries have been read. It MAY be 123 * called after all entries have been read with no ill effects, but this is 124 * not necessary as the entry source will have already been closed after all 125 * entries have been read. 126 */ 127 public abstract void close(); 128}