TypeSet


1   /**
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3    * ("Software"), with or without modification, are permitted provided
4    * that the following conditions are met:
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18   *    please contact info@exolab.org.
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21   *    nor may "Exolab" appear in their names without prior written
22   *    permission of Exoffice Technologies. Exolab is a registered
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26   *    (http://www.exolab.org/).
27   *
28   * THIS SOFTWARE IS PROVIDED BY EXOFFICE TECHNOLOGIES AND CONTRIBUTORS
29   * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
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34   * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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38   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
39   * OF THE POSSIBILITY OF SUCH DAMAGE.
40   *
41   * Copyright 2001-2003 (C) Exoffice Technologies Inc. All Rights Reserved.
42   *
43   * $Id: TypeSet.java,v 1.1 2004/11/26 01:51:16 tanderson Exp $
44   */
45  
46  package org.exolab.jms.tools.db;
47  
48  import java.sql.Connection  ;
49  import java.sql.ResultSet  ;
50  import java.sql.SQLException  ;
51  import java.util.ArrayList  ;
52  import java.util.HashMap  ;
53  import java.util.Iterator  ;
54  
55  import org.apache.commons.logging.Log;
56  import org.apache.commons.logging.LogFactory;
57  
58  import org.exolab.jms.persistence.PersistenceException;
59  import org.exolab.jms.persistence.SQLHelper;
60  
61  
62  /**
63   * A helper class for managing the set of types supported by an RDBMS
64   *
65   * @version     $Revision: 1.1 $ $Date: 2004/11/26 01:51:16 $
66   * @author      <a HREF="mailto:tima@intalio.com">Tim Anderson</a>
67   */
68  class TypeSet {
69  
70      /**
71       * A map of type identifiers to an ArrayList of corresponding RDBMS types
72       */
73      private HashMap   _types = new HashMap  ();
74  
75      /**
76       * The logger
77       */
78      private static final Log _log = LogFactory.getLog(TypeSet.class);
79  
80  
81      /**
82       * Construct a new instance
83       *
84       * @param connection the database connection to obtain meta-data from
85       * @throws PersistenceException if meta-data cannot be accessed
86       */
87      public TypeSet(Connection   connection) throws PersistenceException {
88          ResultSet   set = null;
89          try {
90              set = connection.getMetaData().getTypeInfo();
91              while (set.next()) {
92                  int type = set.getInt("DATA_TYPE");
93                  String   name = set.getString("TYPE_NAME");
94                  long precision = set.getLong("PRECISION");
95                  String   createParams = set.getString("CREATE_PARAMS");
96  
97                  Descriptor descriptor = Descriptor.getDescriptor(type);
98                  if (descriptor != null) {
99                      addType(type, name, precision, createParams);
100                 } else {
101                     _log.debug(
102                         "TypeSet: skipping unknown type, type id=" + type
103                         + ", name=" + name + ", precision=" + precision
104                         + ", create params=" + createParams);
105                 }
106             }
107         } catch (SQLException   exception) {
108             throw new PersistenceException(
109                 "Failed to get type meta-data", exception);
110         } finally {
111             SQLHelper.close(set);
112         }
113     }
114 
115     /**
116      * Return the closest type matching the requested type id and precision
117      *
118      * @param type the type identifier
119      * @param precision the requested precision
120      * @return the closest matching type, or null if none exists
121      */
122     public Type getType(int type, long precision) {
123         Type result = null;
124         ArrayList   types = (ArrayList  ) _types.get(new Integer  (type));
125         if (types != null) {
126             Iterator   iter = types.iterator();
127             while (iter.hasNext()) {
128                 Type option = (Type) iter.next();
129                 if (precision == -1 && (option.getPrecision() != -1 &&
130                     option.getParameters())) {
131                     // no precision was requested, but the type requires
132                     // parameters
133                     result = new Type(type, option.getName(),
134                         option.getPrecision(),
135                         option.getParameters());
136                     break;
137                 } else if (precision <= option.getPrecision()) {
138                     // use the requested precision
139                     result = new Type(type, option.getName(), precision,
140                         option.getParameters());
141                     break;
142                 } else {
143                     _log.debug("TypeSet: requested type=" + type
144                         + " exceeds precision for supported " + option);
145                 }
146             }
147         } else {
148             _log.debug("TypeSet: no types matching type id=" + type
149                 + ", type=" + Descriptor.getDescriptor(type).getName());
150         }
151         return result;
152     }
153 
154     /**
155      * Return the near type matching the supplied type id and precision.
156      * This should only be invoked if the requested precision exceeds that
157      * supported by the database.
158      *
159      * @param type the type identifier
160      * @return the type, or null, if none exists
161      */
162     public Type getNearestType(int type, long precision) {
163         Type result = null;
164         ArrayList   types = (ArrayList  ) _types.get(new Integer  (type));
165         if (types != null) {
166             Iterator   iter = types.iterator();
167             Type nearest = null;
168             while (iter.hasNext()) {
169                 Type option = (Type) iter.next();
170                 if (precision <= option.getPrecision()) {
171                     // use the requested precision
172                     result = new Type(type, option.getName(), precision,
173                         option.getParameters());
174                     break;
175                 } else {
176                     nearest = option;
177                 }
178             }
179             if (result == null && nearest != null) {
180                 // use the closest precision
181                 result = new Type(type, nearest.getName(),
182                     nearest.getPrecision(),
183                     nearest.getParameters());
184                 _log.warn(
185                     "TypeSet: requested type=" + type + ", precision="
186                     + precision + " exceeds precision supported by database. "
187                     + "Falling back to " + nearest);
188             }
189         } else {
190             _log.debug("TypeSet: no types matching type id=" + type
191                 + ", type=" + Descriptor.getDescriptor(type).getName());
192         }
193         return result;
194     }
195 
196     /**
197      * Returns true if the type is supported
198      *
199      * @param type the type identifier
200      * @return <code>true</code> if the type is supported
201      */
202     public boolean exists(int type) {
203         return _types.containsKey(new Integer  (type));
204     }
205 
206 
207     private void addType(int type, String   name, long precision,
208                          String   createParams) {
209         Descriptor descriptor = Descriptor.getDescriptor(type);
210         boolean parameters = false;
211         if (createParams != null && createParams.trim().length() != 0) {
212             parameters = true;
213         }
214 
215         Integer   key = new Integer  (type);
216         ArrayList   types = (ArrayList  ) _types.get(key);
217         if (types == null) {
218             types = new ArrayList  ();
219             _types.put(key, types);
220         }
221 
222         _log.debug("TypeSet: type id=" + type
223             + ", type=" + descriptor.getName()
224             + ", name=" + name
225             + ", precision=" + precision
226             + ", createParams=" + createParams);
227         types.add(new Type(type, name, precision, parameters));
228     }
229 
230 } //-- TypeSet
231
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