Source code: org/objectstyle/cayenne/access/trans/QueryAssembler.java
1 /* ====================================================================
2 *
3 * The ObjectStyle Group Software License, Version 1.0
4 *
5 * Copyright (c) 2002-2003 The ObjectStyle Group
6 * and individual authors of the software. All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 *
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in
17 * the documentation and/or other materials provided with the
18 * distribution.
19 *
20 * 3. The end-user documentation included with the redistribution, if
21 * any, must include the following acknowlegement:
22 * "This product includes software developed by the
23 * ObjectStyle Group (http://objectstyle.org/)."
24 * Alternately, this acknowlegement may appear in the software itself,
25 * if and wherever such third-party acknowlegements normally appear.
26 *
27 * 4. The names "ObjectStyle Group" and "Cayenne"
28 * must not be used to endorse or promote products derived
29 * from this software without prior written permission. For written
30 * permission, please contact andrus@objectstyle.org.
31 *
32 * 5. Products derived from this software may not be called "ObjectStyle"
33 * nor may "ObjectStyle" appear in their names without prior written
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36 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
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48 * ====================================================================
49 *
50 * This software consists of voluntary contributions made by many
51 * individuals on behalf of the ObjectStyle Group. For more
52 * information on the ObjectStyle Group, please see
53 * <http://objectstyle.org/>.
54 *
55 */
56 package org.objectstyle.cayenne.access.trans;
57
58 import java.sql.PreparedStatement;
59 import java.util.ArrayList;
60 import java.util.List;
61
62 import org.apache.log4j.Level;
63 import org.apache.log4j.Logger;
64 import org.objectstyle.cayenne.access.QueryLogger;
65 import org.objectstyle.cayenne.access.QueryTranslator;
66 import org.objectstyle.cayenne.map.DbAttribute;
67 import org.objectstyle.cayenne.map.DbEntity;
68 import org.objectstyle.cayenne.map.DbRelationship;
69
70 /**
71 * Abstract superclass of Query translators.
72 *
73 * @author Andrei Adamchik
74 */
75 public abstract class QueryAssembler extends QueryTranslator {
76 private static Logger logObj = Logger.getLogger(QueryAssembler.class);
77
78 /** PreparedStatement values. */
79 protected List values = new ArrayList();
80
81 /**
82 * PreparedStatement attributes matching entries in <code>values</code>
83 * list.
84 */
85 protected List attributes = new ArrayList();
86
87 /** Processes a join being added. */
88 public abstract void dbRelationshipAdded(DbRelationship dbRel);
89
90 /**
91 * Translates query into sql string. This is a workhorse
92 * method of QueryAssembler. It is called internally from
93 * <code>createStatement</code>. Usually there is no need
94 * to invoke it explicitly.
95 */
96 public abstract String createSqlString() throws Exception;
97
98 public String aliasForTable(DbEntity ent, DbRelationship rel) {
99 return aliasForTable(ent); //Default implementation
100 }
101
102 /**
103 * Returns a name that can be used as column alias.
104 * This can be one of the following:
105 * <ul>
106 * <li>an alias for this table, if it uses aliases</li>
107 * <li>a fully qualified table name, if not.</li>
108 * </ul>
109 *
110 * CayenneRuntimeException is thrown if a table alias
111 * can not be created.
112 */
113 public abstract String aliasForTable(DbEntity dbEnt);
114
115 /** Returns <code>true</code> if table aliases are supported.
116 * Default implementation returns false. */
117 public boolean supportsTableAliases() {
118 return false;
119 }
120
121 /** Registers <code>anObject</code> as a PreparedStatement paramter.
122 *
123 * @param anObject object that represents a value of DbAttribute
124 * @param dbAttr DbAttribute being processed.
125 */
126 public void addToParamList(DbAttribute dbAttr, Object anObject) {
127 attributes.add(dbAttr);
128 values.add(anObject);
129 }
130
131 /** Translates internal query into PreparedStatement. */
132 public PreparedStatement createStatement(Level logLevel) throws Exception {
133 long t1 = System.currentTimeMillis();
134 String sqlStr = createSqlString();
135 QueryLogger.logQuery(
136 logLevel,
137 sqlStr,
138 values,
139 System.currentTimeMillis() - t1);
140 PreparedStatement stmt = con.prepareStatement(sqlStr);
141 initStatement(stmt);
142 return stmt;
143 }
144
145 /**
146 * Initializes prepared statements with collected parameters.
147 * Called internally from "createStatement". Cayenne users
148 * shouldn't normally call it directly.
149 */
150 protected void initStatement(PreparedStatement stmt) throws Exception {
151 if (values != null && values.size() > 0) {
152 int len = values.size();
153 for (int i = 0; i < len; i++) {
154 Object val = values.get(i);
155
156 DbAttribute attr = (DbAttribute) attributes.get(i);
157
158 // null DbAttributes are a result of inferior qualifier processing
159 // (qualifier can't map parameters to DbAttributes and therefore
160 // only supports standard java types now)
161 // hence, a special moronic case here:
162 if (attr == null) {
163 stmt.setObject(i + 1, val);
164 } else {
165 int type = attr.getType();
166 int precision = attr.getPrecision();
167 adapter.bindParameter(stmt, val, i + 1, type, precision);
168 }
169 }
170 }
171 }
172 }