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1   package org.apache.torque.engine.database.model;
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.util.List;
23  
24  import org.apache.commons.logging.Log;
25  import org.apache.commons.logging.LogFactory;
26  
27  import org.apache.torque.engine.EngineException;
28  
29  /***
30   * A <code>NameGenerator</code> implementation for table-specific
31   * constraints.  Conforms to the maximum column name length for the
32   * type of database in use.
33   *
34   * @author <a href="mailto:dlr@finemaltcoding.com>Daniel Rall</a>
35   * @version $Id: ConstraintNameGenerator.java 473814 2006-11-11 22:30:30Z tv $
36   */
37  public class ConstraintNameGenerator implements NameGenerator
38  {
39      /*** Logging class from commons.logging */
40      private static Log log = LogFactory.getLog(ConstraintNameGenerator.class);
41  
42      /***
43       * First element of <code>inputs</code> should be of type {@link
44       * org.apache.torque.engine.database.model.Database}, second
45       * should be a table name, third is the type identifier (spared if
46       * trimming is necessary due to database type length constraints),
47       * and the fourth is a <code>Integer</code> indicating the number
48       * of this contraint.
49       *
50       * @see org.apache.torque.engine.database.model.NameGenerator
51       */
52      public String generateName(List inputs)
53          throws EngineException
54      {
55          StringBuffer name = new StringBuffer();
56          Database db = (Database) inputs.get(0);
57          name.append((String) inputs.get(1));
58          String namePostfix = (String) inputs.get(2);
59          String constraintNbr = inputs.get(3).toString();
60  
61          // Calculate maximum RDBMS-specific column character limit.
62          int maxBodyLength = -1;
63          try
64          {
65              int maxColumnNameLength = db.getPlatform().getMaxColumnNameLength();
66              maxBodyLength = (maxColumnNameLength - namePostfix.length()
67                      - constraintNbr.length() - 2);
68  
69              if (log.isDebugEnabled())
70              {
71                  log.debug("maxColumnNameLength=" + maxColumnNameLength
72                          + " maxBodyLength=" + maxBodyLength);
73              }
74          }
75          catch (NumberFormatException maxLengthUnknown)
76          {
77          }
78  
79          // Do any necessary trimming.
80          if (maxBodyLength != -1 && name.length() > maxBodyLength)
81          {
82              name.setLength(maxBodyLength);
83          }
84  
85          name.append(STD_SEPARATOR_CHAR).append(namePostfix)
86              .append(STD_SEPARATOR_CHAR).append(constraintNbr);
87  
88          return name.toString();
89      }
90  }