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Java > Open Source Codes > org > apache > torque > oid > SequenceIdGenerator


1 package org.apache.torque.oid;
2
3 /*
4  * Licensed to the Apache Software Foundation (ASF) under one
5  * or more contributor license agreements. See the NOTICE file
6  * distributed with this work for additional information
7  * regarding copyright ownership. The ASF licenses this file
8  * to you under the Apache License, Version 2.0 (the
9  * "License"); you may not use this file except in compliance
10  * with the License. You may obtain a copy of the License at
11  *
12  * http://www.apache.org/licenses/LICENSE-2.0
13  *
14  * Unless required by applicable law or agreed to in writing,
15  * software distributed under the License is distributed on an
16  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17  * KIND, either express or implied. See the License for the
18  * specific language governing permissions and limitations
19  * under the License.
20  */
21
22 import java.math.BigDecimal JavaDoc;
23 import java.sql.Connection JavaDoc;
24
25 import org.apache.commons.logging.Log;
26 import org.apache.commons.logging.LogFactory;
27
28 import org.apache.torque.adapter.DB;
29 import org.apache.torque.util.SQLBuilder;
30
31 import com.workingdogs.village.QueryDataSet;
32 import com.workingdogs.village.Record;
33 import com.workingdogs.village.Value;
34
35 /**
36  * This generator works with databases that have an sql syntax for
37  * getting an id prior to inserting a row into the database.
38  *
39  * @author <a HREF="mailto:jmcnally@collab.net">John D. McNally</a>
40  * @version $Id: SequenceIdGenerator.java 473821 2006-11-11 22:37:25Z tv $
41  */
42 public class SequenceIdGenerator implements IdGenerator
43 {
44     /** The log. */
45     private static Log log = LogFactory.getLog(SequenceIdGenerator.class);
46
47     /** the adapter that knows the correct sql syntax */
48     private DB dbAdapter;
49
50     /** The internal name of the Database that this Generator is connected to */
51     private String JavaDoc name = null;
52
53     /**
54      * Creates an IdGenerator which will work with the specified database.
55      *
56      * @param dbAdapter the adapter that knows the correct sql syntax.
57      * @param name The name of the datasource to find the correct schema
58      */
59     public SequenceIdGenerator(final DB dbAdapter, final String JavaDoc name)
60     {
61         this.dbAdapter = dbAdapter;
62         this.name = name;
63     }
64
65     /**
66      * Retrieves an id as an int.
67      *
68      * @param connection A Connection.
69      * @param keyInfo an Object that contains additional info.
70      * @return An int with the value for the id.
71      * @exception Exception Database error.
72      */
73     public int getIdAsInt(Connection JavaDoc connection, Object JavaDoc keyInfo)
74         throws Exception JavaDoc
75     {
76         return getIdAsVillageValue(connection, keyInfo).asInt();
77     }
78
79     /**
80      * Retrieves an id as an long.
81      *
82      * @param connection A Connection.
83      * @param keyInfo an Object that contains additional info.
84      * @return A long with the value for the id.
85      * @exception Exception Database error.
86      */
87     public long getIdAsLong(Connection JavaDoc connection, Object JavaDoc keyInfo)
88         throws Exception JavaDoc
89     {
90         return getIdAsVillageValue(connection, keyInfo).asLong();
91     }
92
93     /**
94      * Retrieves an id as a BigDecimal.
95      *
96      * @param connection A Connection.
97      * @param keyInfo an Object that contains additional info.
98      * @return A BigDecimal id
99      * @exception Exception Database error.
100      */
101     public BigDecimal JavaDoc getIdAsBigDecimal(Connection JavaDoc connection, Object JavaDoc keyInfo)
102         throws Exception JavaDoc
103     {
104         return getIdAsVillageValue(connection, keyInfo).asBigDecimal();
105     }
106
107     /**
108      * Retrieves an id as an String.
109      *
110      * @param connection A Connection.
111      * @param keyInfo an Object that contains additional info.
112      * @return A String id
113      * @exception Exception Database error.
114      */
115     public String JavaDoc getIdAsString(Connection JavaDoc connection, Object JavaDoc keyInfo)
116         throws Exception JavaDoc
117     {
118         return getIdAsVillageValue(connection, keyInfo).asString();
119     }
120
121     /**
122      * A flag to determine the timing of the id generation
123      *
124      * @return a <code>boolean</code> value
125      */
126     public boolean isPriorToInsert()
127     {
128         return true;
129     }
130
131     /**
132      * A flag to determine the timing of the id generation
133      *
134      * @return a <code>boolean</code> value
135      */
136     public boolean isPostInsert()
137     {
138         return false;
139     }
140
141     /**
142      * A flag to determine whether a Connection is required to
143      * generate an id.
144      *
145      * @return a <code>boolean</code> value
146      */
147     public boolean isConnectionRequired()
148     {
149         return true;
150     }
151
152     /**
153      * Retrieves an id as a Village Value.
154      *
155      * @param connection A Connection.
156      * @param keyInfo an Object that contains additional info.
157      * @return A Village Value id.
158      * @exception Exception Database error.
159      */
160     private Value getIdAsVillageValue(Connection JavaDoc connection, Object JavaDoc keyInfo)
161         throws Exception JavaDoc
162     {
163         String JavaDoc sequenceName = SQLBuilder.getFullTableName(String.valueOf(keyInfo), name);
164         String JavaDoc idSql = dbAdapter.getIDMethodSQL(sequenceName);
165         if (log.isDebugEnabled())
166         {
167             log.debug(idSql);
168         }
169
170         // Execute the query.
171 QueryDataSet qds = new QueryDataSet(connection, idSql);
172         Record rec;
173         try
174         {
175             qds.fetchRecords(1);
176             rec = qds.getRecord(0); // Records are 0 based.
177 }
178         finally
179         {
180             qds.close();
181         }
182         return rec.getValue(1); // Values are 1 based.
183 }
184 }
185
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