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Java > Open Source Codes > smallsql > database > Command


1 /* =============================================================
2  * SmallSQL : a free Java DBMS library for the Java(tm) platform
3  * =============================================================
4  *
5  * (C) Copyright 2004-2006, by Volker Berlin.
6  *
7  * Project Info: http://www.smallsql.de/
8  *
9  * This library is free software; you can redistribute it and/or modify it
10  * under the terms of the GNU Lesser General Public License as published by
11  * the Free Software Foundation; either version 2.1 of the License, or
12  * (at your option) any later version.
13  *
14  * This library is distributed in the hope that it will be useful, but
15  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
16  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
17  * License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public
20  * License along with this library; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
22  * USA.
23  *
24  * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
25  * in the United States and other countries.]
26  *
27  * ---------------
28  * Command.java
29  * ---------------
30  * Author: Volker Berlin
31  *
32  */

33 package smallsql.database;
34
35 import java.sql.*;
36
37
38 abstract class Command {
39
40     int type;
41     String JavaDoc catalog;
42     String JavaDoc name;
43
44     SSResultSet rs;
45     int updateCount = -1;
46
47     /** List of Columns */
48     final Expressions columnExpressions;
49
50     /** List of ExpressionValue */
51     Expressions params = new Expressions();
52
53     final Logger log;
54     
55     Command(Logger log){
56         this.log = log;
57         this.columnExpressions = new Expressions();
58     }
59
60     Command(Logger log, Expressions columnExpressions){
61         this.log = log;
62         this.columnExpressions = columnExpressions;
63     }
64
65     
66     /**
67      * Add a Expression that returns the value for Column. This method is used
68      * from SQLParser for different Commands (CommandSelect, CommandInsert).
69      * @see SQLParser#select()
70      * @see SQLParser#insert()
71      */

72     void addColumnExpression( Expression column ){
73         columnExpressions.add( column );
74     }
75
76     void addParameter( ExpressionValue param ){
77         params.add( param );
78     }
79     
80
81     /**
82      * check if all parameters are set
83      */

84     void verifyParams() throws SQLException{
85         for(int p=0; p<params.size(); p++){
86             if(((ExpressionValue)params.get(p)).isEmpty())
87                 throw Utils.createSQLException("Parameter " + (p+1) + " is empty.");
88         }
89     }
90
91     /**
92      * Clear all parameters of a PreparedStatement
93      */

94     void clearParams(){
95         for(int p=0; p<params.size(); p++){
96             ((ExpressionValue)params.get(p)).clear();
97         }
98     }
99
100     /**
101      * Get a PreparedStatement parameter.
102      * The idx starts with 1.
103      */

104     private ExpressionValue getParam(int idx) throws SQLException{
105         if(idx < 1 || idx > params.size())
106             throw Utils.createSQLException("Parameter index " +idx+ " out of range. The value must be between 1 and " + params.size());
107         return ((ExpressionValue)params.get(idx-1));
108     }
109     
110     /**
111      * Set value of a PreparedStatement parameter.
112      * The idx starts with 1.
113      */

114     void setParamValue(int idx, Object JavaDoc value, int dataType) throws SQLException{
115         getParam(idx).set( value, dataType );
116         if(log.isLogging()){
117             log.println("param"+idx+'='+value+"; type="+dataType);
118         }
119     }
120
121     /**
122      * Set value of a PreparedStatement parameter.
123      * The idx starts with 1.
124      */

125     void setParamValue(int idx, Object JavaDoc value, int dataType, int length) throws SQLException{
126         getParam(idx).set( value, dataType, length );
127         if(log.isLogging()){
128             log.println("param"+idx+'='+value+"; type="+dataType+"; length="+length);
129         }
130     }
131
132     final void execute(SSConnection con, SSStatement st) throws SQLException{
133         int savepoint = con.getSavepoint();
134         try{
135             executeImpl( con, st );
136         }catch(Throwable JavaDoc e){
137             con.rollback(savepoint);
138             throw Utils.createSQLException(e);
139         }finally{
140             if(con.getAutoCommit()) con.commit();
141         }
142     }
143
144     abstract void executeImpl(SSConnection con, SSStatement st) throws Exception JavaDoc;
145
146     SSResultSet getQueryResult() throws SQLException{
147         if(rs == null)
148             throw Utils.createSQLException("No ResultSet was produce.");
149         return rs;
150     }
151
152     SSResultSet getResultSet(){
153         return rs;
154     }
155
156     int getUpdateCount(){
157         return updateCount;
158     }
159     
160     
161     /**
162      * The default Command remove all results because there is only one result.
163      * @return ever false
164      */

165     boolean getMoreResults(){
166         rs = null;
167         updateCount = -1;
168         return false;
169     }
170     
171     
172     /**
173      * Set the max rows. Need to be override in the Commands that support it.
174      */

175     void setMaxRows(int max){/* Empty because not supported for the most Commands */}
176     
177     
178     int getMaxRows(){return 0;}
179 }
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