KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > org > apache > torque > engine > database > model > ConstraintNameGenerator


1 package org.apache.torque.engine.database.model;
2
3 /*
4  * Copyright 2001-2004 The Apache Software Foundation.
5  *
6  * Licensed under the Apache License, Version 2.0 (the "License");
7  * you may not use this file except in compliance with the License.
8  * You may obtain a copy of the License at
9  *
10  * http://www.apache.org/licenses/LICENSE-2.0
11  *
12  * Unless required by applicable law or agreed to in writing, software
13  * distributed under the License is distributed on an "AS IS" BASIS,
14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15  * See the License for the specific language governing permissions and
16  * limitations under the License.
17  */
18
19 import java.util.List JavaDoc;
20
21 import org.apache.commons.logging.Log;
22 import org.apache.commons.logging.LogFactory;
23
24 import org.apache.torque.engine.EngineException;
25
26 /**
27  * A <code>NameGenerator</code> implementation for table-specific
28  * constraints. Conforms to the maximum column name length for the
29  * type of database in use.
30  *
31  * @author <a HREF="mailto:dlr@finemaltcoding.com>Daniel Rall</a>
32  * @version $Id: ConstraintNameGenerator.java,v 1.4 2004/02/22 06:27:19 jmcnally Exp $
33  */
34 public class ConstraintNameGenerator implements NameGenerator
35 {
36     /** Logging class from commons.logging */
37     private static Log log = LogFactory.getLog(ConstraintNameGenerator.class);
38
39     /**
40      * First element of <code>inputs</code> should be of type {@link
41      * org.apache.torque.engine.database.model.Database}, second
42      * should be a table name, third is the type identifier (spared if
43      * trimming is necessary due to database type length constraints),
44      * and the fourth is a <code>Integer</code> indicating the number
45      * of this contraint.
46      *
47      * @see org.apache.torque.engine.database.model.NameGenerator
48      */
49     public String JavaDoc generateName(List JavaDoc inputs)
50         throws EngineException
51     {
52         StringBuffer JavaDoc name = new StringBuffer JavaDoc();
53         Database db = (Database) inputs.get(0);
54         name.append((String JavaDoc) inputs.get(1));
55         String JavaDoc namePostfix = (String JavaDoc) inputs.get(2);
56         String JavaDoc constraintNbr = inputs.get(3).toString();
57
58         // Calculate maximum RDBMS-specific column character limit.
59 int maxBodyLength = -1;
60         try
61         {
62             int maxColumnNameLength = db.getPlatform().getMaxColumnNameLength();
63             maxBodyLength = (maxColumnNameLength - namePostfix.length()
64                     - constraintNbr.length() - 2);
65
66             if (log.isDebugEnabled())
67             {
68                 log.debug("maxColumnNameLength=" + maxColumnNameLength
69                         + " maxBodyLength=" + maxBodyLength);
70             }
71         }
72         catch (NumberFormatException JavaDoc maxLengthUnknown)
73         {
74         }
75
76         // Do any necessary trimming.
77 if (maxBodyLength != -1 && name.length() > maxBodyLength)
78         {
79             name.setLength(maxBodyLength);
80         }
81
82         name.append(STD_SEPARATOR_CHAR).append(namePostfix)
83             .append(STD_SEPARATOR_CHAR).append(constraintNbr);
84
85         return name.toString();
86     }
87 }
88
Popular Tags