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Java > Open Source Codes > org > exolab > jms > tools > db > TypeMapper


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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12  * following disclaimer in the documentation and/or other
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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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25  * 5. Due credit should be given to the Exolab Project
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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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37  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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 (C) Exoffice Technologies Inc. All Rights Reserved.
42  *
43  * $Id: TypeMapper.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.Types JavaDoc;
49 import java.util.HashMap JavaDoc;
50
51 import org.apache.commons.logging.Log;
52 import org.apache.commons.logging.LogFactory;
53
54
55 /**
56  * A helper class for mapping between types.</br>
57  * NOTE: this mapping is not complete, only reflecting those types required
58  * by OpenJMS
59  *
60  * @version $Revision: 1.1 $ $Date: 2004/11/26 01:51:16 $
61  * @author <a HREF="mailto:tma@netspace.net.au">Tim Anderson</a>
62  */
63 class TypeMapper {
64
65     /**
66      * The set of types supported by the RDBMS
67      */
68     private TypeSet _set = null;
69
70     /**
71      * A mapping of SQL type identifiers to their corresponding alternative
72      * types. The alternatives are represented as an array of Type
73      */
74     private HashMap JavaDoc _mappings = new HashMap JavaDoc();
75
76     /**
77      * The logger
78      */
79     private static final Log _log = LogFactory.getLog(TypeMapper.class);
80
81
82     /**
83      * Construct the type mapper with the set of type supported by the
84      * RDBMS
85      */
86     public TypeMapper(TypeSet set) {
87         _set = set;
88
89         // alternatives for the Types.BINARY type
90 Type[] binaries = {new Type(Types.VARBINARY, 0, true),
91                            new Type(Types.LONGVARBINARY, 0, true)};
92         add(Types.BINARY, binaries);
93
94         // alternatives for the Types.VARBINARY type
95 Type[] varbinaries = {new Type(Types.LONGVARBINARY, 0, true)};
96         add(Types.VARBINARY, binaries);
97
98         // alternatives for the Types.BIT type
99 Type[] bits = {new Type(Types.CHAR, 0, false),
100                        new Type(Types.TINYINT, 0, false),
101                        new Type(Types.SMALLINT, 0, false),
102                        new Type(Types.INTEGER, 0, false),
103                        new Type(Types.NUMERIC, 1, true)};
104         add(Types.BIT, bits);
105
106         // alternatives for the Types.DECIMAL type
107 Type[] decimals = {new Type(Types.NUMERIC, 0, false)};
108         add(Types.DECIMAL, decimals);
109
110         // alternatives for the Types.DATE type
111 Type[] dates = {new Type(Types.TIMESTAMP, 0, false)};
112         add(Types.DATE, dates);
113
114         // alternatives for the Types.BIGINT type
115 long precision = Long.toString(Long.MAX_VALUE).length();
116         Type[] bigints = {new Type(Types.NUMERIC, precision, true)};
117         add(Types.BIGINT, bigints);
118     }
119
120     public Type getType(int type, long precision) {
121         // check if type set supports the requested type directly
122 Type result = _set.getType(type, precision);
123         if (result == null) {
124             // type not supported so return the mapping, if one is available
125 result = (Type) _mappings.get(new Integer JavaDoc(type));
126         }
127         return result;
128     }
129
130     private void add(int type, Type[] mappings) {
131         for (int i = 0; i < mappings.length; ++i) {
132             Type requested = mappings[i];
133             Type supported = _set.getType(requested.getType(),
134                 requested.getPrecision());
135             if (supported == null) {
136                 _log.debug(
137                     "TypeMapper: alternative mapping for type=" +
138                     Descriptor.getDescriptor(type).getName() +
139                     " is not supported by the database");
140             } else {
141                 long precision = requested.getPrecision();
142                 long maxPrecision = supported.getPrecision();
143                 _log.debug(
144                     "TypeMapper: alternative mapping for type=" +
145                     Descriptor.getDescriptor(type).getName() +
146                     ", precision=" + precision +
147                     ", is supported by the database as " + supported);
148                 if (type == supported.getType() &&
149                     ((precision > 0) && (precision < maxPrecision))) {
150                     // if the requested type is supported by the database, and
151 // has a smaller precision, override the maximum precision
152 // defined by the supported type
153 supported = new Type(
154                         supported.getType(), supported.getName(),
155                         precision, supported.getParameters());
156                 }
157                 _mappings.put(new Integer JavaDoc(type), supported);
158                 break;
159             }
160         }
161     }
162
163 } //-- TypeMapper
164
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