ColumnRef


1   /*
2    * The contents of this file are subject to the 
3    * Mozilla Public License Version 1.1 (the "License"); 
4    * you may not use this file except in compliance with the License. 
5    * You may obtain a copy of the License at http://www.mozilla.org/MPL/
6    *
7    * Software distributed under the License is distributed on an "AS IS"
8    * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. 
9    * See the License for the specific language governing rights and 
10   * limitations under the License.
11   *
12   * The Initial Developer of the Original Code is Simulacra Media Ltd.
13   * Portions created by Simulacra Media Ltd are Copyright (C) Simulacra Media Ltd, 2004.
14   *
15   * All Rights Reserved.
16   *
17   * Contributor(s):
18   */
19  package org.openharmonise.commons.dsi;
20  
21  /**
22   * A coloumn reference in a relational database with a table name, 
23   * a column name, a data type and possibly an alias for the table name.
24   * 
25   * @author Michael Bell
26   * @version $Revision: 1.1 $
27   *
28   */
29  public class ColumnRef extends Object   {
30      
31      /**
32       * Constant indicating a date data type
33       */
34      static public int DATE = 0;
35      
36      /**
37       * Constant indicating a text data type
38       */
39      static public int TEXT = 1;
40      
41      /**
42       * Constant indicating a number data type
43       */
44      static public int NUMBER = 2;
45      
46      /**
47       * Constant indicating a long text data type
48       */
49      static public int LONG_TEXT = 3;
50      
51      /**
52       * The name of the table containing the column
53       */
54      private String   m_sTable = null;
55      
56      /**
57       * The alias for the table name
58       */
59      private String   m_sTableAlias = null;
60      
61      /**
62       * The name of the column
63       */
64      private String   m_sColumn = null;
65      
66      /**
67       * The data type of the column
68       */
69      private int m_nDataType = 1;
70      
71      /**
72       * The cached full string representation of this column reference
73       */
74      private String   m_sFullRefCache = null;
75      
76      /**
77       * Hashcode for this object
78       */
79      private int m_nHashcode = 0;
80  
81      /**
82       * Constructs a column reference.
83       * 
84       * @param sTable the name of table containing the column
85       * @param sColumn the name of the column
86       * @param nDataType the data type
87       * @throws DataStoreException if any of the parameters are invalid
88       */
89      public ColumnRef(String   sTable, String   sColumn, int nDataType)
90                throws DataStoreException {
91          if ((sTable == null) || (sColumn == null)) {
92              throw new DataStoreException("Invalid Type: table:" + sTable +
93                                           ",column:" + sColumn);
94          }
95  
96          if ((nDataType < DATE) || (nDataType > LONG_TEXT)) {
97              throw new DataStoreException("Invalid data type");
98          }
99  
100         m_sTable = sTable;
101         m_sColumn = sColumn;
102         m_nDataType = nDataType;
103     }
104 
105     /**
106      * Returns the name of the table containing the column.
107      * 
108      * @return the name of the table containing the column
109      */
110     public String   getTable() {
111         return m_sTable;
112     }
113 
114     /**
115      * Sets the name of the table containing the column.
116      * 
117      * @param sTable the name of the table containing the column
118      */
119     public void setTable(String   sTable) {
120         if( this.m_sFullRefCache!=null ) {
121           this.m_sFullRefCache=null;
122         }
123         m_sTable = sTable;
124     }
125     
126     /**
127      * Returns the alias for the table name.
128      * 
129      * @return the alias for the table name
130      */
131     public String   getTableAlias() {
132         return m_sTableAlias;
133     }
134 
135     /**
136      * Sets the alias for the table name.
137      * 
138      * @param sTableAlias the alias for the table name
139      */
140     public void setTableAlias(String   sTableAlias) {
141         if( this.m_sFullRefCache!=null ) {
142           this.m_sFullRefCache=null;
143         }
144         
145         m_sTableAlias = sTableAlias;
146     }
147     
148     /**
149      * Returns <code>true</code> if the table name has an alias set.
150      * 
151      * @return <code>true</code> if the table name has an alias set.
152      */
153     public boolean hasTableAlias() {
154         return (m_sTableAlias != null);
155     }
156 
157     /**
158      * Returns the name of the column.
159      * 
160      * @return the name of the column
161      */
162     public String   getColumn() {
163         return m_sColumn;
164     }
165 
166     /**
167      * Sets the name of the column.
168      * 
169      * @param sColumn the name of the column
170      */
171     public void setColumn(String   sColumn) {
172         if( this.m_sFullRefCache!=null ) {
173           this.m_sFullRefCache=null;
174         }
175         m_sColumn = sColumn;
176     }
177 
178     /**
179      * Returns the full string representation of this column reference.
180      * 
181      * @return the full string representation of this column reference
182      */
183     public String   getFullRef() {
184         if( this.m_sFullRefCache==null ) {
185             String   sTable = m_sTable;
186             if(hasTableAlias() == true) {
187                 sTable = m_sTableAlias;
188             }
189             
190             m_sFullRefCache= sTable + "." + m_sColumn;
191         }
192         return this.m_sFullRefCache;
193     }
194 
195     /**
196      * Returns the data type of this column.
197      * 
198      * @return the data type of this column
199      */
200     public int getDataType() {
201         return m_nDataType;
202     }
203     
204     
205     /* (non-Javadoc)
206      * @see java.lang.Object#equals(java.lang.Object)
207      */
208     public boolean equals(Object   obj) {
209         boolean bEq = false;
210         
211         if (this == obj) {
212             bEq = true;
213         } else if(obj instanceof ColumnRef) {
214             ColumnRef colref = (ColumnRef) obj;
215             
216             if(colref.getColumn().equals(getColumn()) == true
217              && colref.getTable().equals(getTable())) {
218                 bEq = true;
219             }
220         }
221         
222         return bEq;
223     }
224     
225     /* (non-Javadoc)
226      * @see java.lang.Object#hashCode()
227      */
228     public int hashCode() {
229 
230         if (m_nHashcode == 0) {
231             int nHash = 17;
232 
233             nHash = 37 * nHash + m_nDataType;
234             if (m_sColumn != null) {
235                 nHash = 37 * nHash + m_sColumn.hashCode();
236             }
237             if (m_sTable != null) {
238                 nHash = 37 * nHash + m_sTable.hashCode();
239             }
240             if (m_sTableAlias != null) {
241                 nHash = 37 * nHash + m_sTableAlias.hashCode();
242             }
243             
244             m_nHashcode = nHash;
245         }
246 
247         return m_nHashcode;
248     }
249 
250 }
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