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Java > Open Source Codes > org > objectstyle > cayenne > access > jdbc > RowDescriptor


1 /* ====================================================================
2  *
3  * The ObjectStyle Group Software License, version 1.1
4  * ObjectStyle Group - http://objectstyle.org/
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6  * Copyright (c) 2002-2005, Andrei (Andrus) Adamchik and individual authors
7  * of the software. All rights reserved.
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10  * modification, are permitted provided that the following conditions
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22  * must include the following acknowlegement:
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24  * and hosted on ObjectStyle Group web site (http://objectstyle.org/)."
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26  * if and wherever such third-party acknowlegements normally appear.
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56 package org.objectstyle.cayenne.access.jdbc;
57
58 import java.sql.ResultSet JavaDoc;
59 import java.sql.ResultSetMetaData JavaDoc;
60 import java.sql.SQLException JavaDoc;
61 import java.util.Map JavaDoc;
62
63 import org.objectstyle.cayenne.CayenneRuntimeException;
64 import org.objectstyle.cayenne.access.types.ExtendedType;
65 import org.objectstyle.cayenne.access.types.ExtendedTypeMap;
66
67 /**
68  * A descriptor of a result row obtained from a database.
69  *
70  * @since 1.2
71  * @author Andrei Adamchik
72  */
73 // replaces 1.1 ResultDescriptor
74 public class RowDescriptor {
75
76     protected ColumnDescriptor[] columns;
77     protected ExtendedType[] converters;
78
79     /**
80      * Creates an empty RowDescriptor. Intended mainly for testing and use by subclasses.
81      */
82     protected RowDescriptor() {
83
84     }
85
86     /**
87      * Creates a RowDescriptor for an array of columns.
88      */
89     public RowDescriptor(ColumnDescriptor[] columns, ExtendedTypeMap types) {
90         this.columns = columns;
91         indexTypes(types);
92     }
93
94     /**
95      * Creates new RowDescriptor using ResultSet metadata to determine the columns.
96      */
97     public RowDescriptor(ResultSet JavaDoc resultSet, ExtendedTypeMap types) {
98         this(resultSet, types, null);
99     }
100
101     /**
102      * Creates new RowDescriptor using ResultSet metadata to determine the columns. Note
103      * that if javaTypeOverrides array is null, default JDBC to Java types mapping is
104      * used.
105      */
106     public RowDescriptor(ResultSet JavaDoc resultSet, ExtendedTypeMap types, Map JavaDoc javaTypeOverrides) {
107
108         initFromResultSet(resultSet);
109
110         if (javaTypeOverrides != null) {
111             overrideJavaTypes(javaTypeOverrides);
112         }
113
114         indexTypes(types);
115     }
116
117     /**
118      * Initializes converters for columns.
119      */
120     protected void indexTypes(ExtendedTypeMap types) {
121         this.converters = new ExtendedType[columns.length];
122         for (int i = 0; i < columns.length; i++) {
123             converters[i] = types.getRegisteredType(columns[i].getJavaClass());
124         }
125     }
126
127     /**
128      * Builds columns list from ResultSet metadata.
129      */
130     protected void initFromResultSet(ResultSet JavaDoc resultSet) {
131         try {
132             ResultSetMetaData JavaDoc md = resultSet.getMetaData();
133             int len = md.getColumnCount();
134             if (len == 0) {
135                 throw new CayenneRuntimeException("No columns in ResultSet.");
136             }
137
138             this.columns = new ColumnDescriptor[len];
139
140             for (int i = 0; i < len; i++) {
141                 columns[i] = new ColumnDescriptor(md, i + 1);
142             }
143         }
144         catch (SQLException JavaDoc sqex) {
145             throw new CayenneRuntimeException("Error reading metadata.", sqex);
146         }
147     }
148
149     /**
150      * Overrides Java types of result columns. Keys in the map must correspond to the
151      * names of the columns.
152      */
153     protected void overrideJavaTypes(Map JavaDoc overrides) {
154
155         for (int i = 0; i < columns.length; i++) {
156             String JavaDoc type = (String JavaDoc) overrides.get(columns[i].getName());
157
158             if (type != null) {
159                 columns[i].setJavaClass(type);
160             }
161         }
162     }
163
164     /**
165      * Returns a number of columns in a row.
166      */
167     public int getWidth() {
168         return columns.length;
169     }
170
171     /**
172      * Returns column descriptors.
173      */
174     public ColumnDescriptor[] getColumns() {
175         return columns;
176     }
177
178     /**
179      * Returns extended types for columns.
180      */
181     public ExtendedType[] getConverters() {
182         return converters;
183     }
184 }
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