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/* Version 1.0 based on Apache Software License 1.1
*
* Copyright (c) 2003 Piotr Maj and DBMonster developers. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* 3. The end-user documentation included with the redistribution, if any,
* must include the following acknowledgment:
*
* "This product includes software developed by DBMonster developers
* (http://dbmonster.kernelpanic.pl/)."
*
* Alternately, this acknowledgment may appear in the software itself,
* if and wherever such third-party acknowledgments normally appear.
*
* 4. The name "DBMonster" must not be used to endorse or promote products
* derived from this software without prior written permission. For
* written permission, please contact [email protected].
*
* 5. Products derived from this software may not be called "DBMonster",
* nor may "DBMonster" appear in their name, without prior written
* permission of Piotr Maj.
*
* THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE DBMONSTER DEVELOPERS BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
package pl.kernelpanic.dbmonster.generator;
import java.util.ArrayList;
import java.util.List;
import java.sql.ResultSet;
import org.apache.commons.logging.Log;
import pl.kernelpanic.dbmonster.DBMonster;
import pl.kernelpanic.dbmonster.DBMonsterContext;
import pl.kernelpanic.dbmonster.connection.ConnectionProvider;
import pl.kernelpanic.dbmonster.connection.Transaction;
import pl.kernelpanic.dbmonster.schema.Column;
import pl.kernelpanic.dbmonster.schema.Key;
/**
* The string key generator uses sort of string magic known from Perl.
* in short it starts from i.e. "aaaaa" and increment it by one:
* "aaaab", "aaaac"....
*
* @author Piotr Maj <[email protected]>
*
* @version $Id: StringKeyGenerator.java,v 1.4 2006/01/05 16:29:37 majek Exp $
*/
public class StringKeyGenerator implements KeyGenerator, Initializable {
/**
* Default value.
*/
public static final String DEFAULT_VALUE = "aaaaaaaa";
/**
* The key.
*/
private Key key = null;
/**
* Holds a list of columns.
*/
private List columns = new ArrayList();
/**
* Initial value. A special value of 0 (zero) means that
* initial value should be taken from the database.
*/
private String startValue = "0";
/**
* Context.
*/
private DBMonsterContext context = null;
/**
* Next value.
*/
private String nextValue = DEFAULT_VALUE;
/**
* Chars.
*/
public static final char[] CHARS = new char[26];
static {
for (int i = 'a'; i <= 'z'; i++) {
CHARS[i - 'a'] = (char) i;
}
}
/**
* Sets the key.
*
* @param k the key.
*/
public void setKey(Key k) {
key = k;
}
public Key getKey() {
return key;
}
/**
* Returns columns.
*
* @return a list of columns
*/
public List getColumns() {
return columns;
}
/**
* Generates a primary key.
*
* @return a list of generated Columns.
*
* @throws Exception if generation fails
*/
public List generate() throws Exception {
Column column = (Column) columns.get(0);
if (nextValue == null) {
throw new Exception("No more values available (generator: "
+ getClass().getName() + ", table: "
+ key.getTable().getName() + ").");
}
column.setValue(nextValue);
nextValue = incrementString(nextValue);
return columns;
}
/**
* @see Initializable#initialize(DBMonsterContext)
*/
public void initialize(DBMonsterContext ctx) throws Exception {
context = ctx;
Log log = (Log) context.getProperty(DBMonster.LOGGER_KEY);
if (log.isDebugEnabled()) {
log.debug("Initializing generator <" + getClass().getName() + ">.");
}
if ("0".equals(startValue)) {
ConnectionProvider connProv =
(ConnectionProvider) context.getProperty(
DBMonster.CONNECTION_PROVIDER_KEY);
Transaction tx = new Transaction(connProv);
try {
tx.begin();
Column column = (Column) columns.get(0);
String sql = "SELECT max(" + column.getName() + ") FROM "
+ key.getTable().getName();
if (log.isDebugEnabled()) {
log.debug(sql);
}
ResultSet rs = tx.executeQuery(sql);
if (rs.next()) {
nextValue = rs.getString(1);
if (rs.wasNull() || "".equals(nextValue)) {
nextValue = DEFAULT_VALUE;
}
nextValue = incrementString(nextValue);
} else {
nextValue = DEFAULT_VALUE;
}
tx.commit();
} catch (Exception e) {
if (log.isFatalEnabled()) {
log.fatal(e.getMessage());
}
tx.abort();
throw e;
} finally {
tx.close();
}
} else {
nextValue = startValue;
}
if (log.isDebugEnabled()) {
log.debug("Initialization of generator <"
+ getClass().getName() + "> finished.");
}
}
/**
* Returns a column name.
*
* @return the name of the column.
*/
public String getColumnName() {
if (columns.size() == 1) {
Column column = (Column) columns.get(0);
if (column != null) {
return column.getName();
}
}
return null;
}
/**
* Sets the column name and sets up the column.
*
* @param name the name of the column.
*/
public void setColumnName(String name) {
Column column = new Column();
column.setName(name);
columns = new ArrayList();
columns.add(column);
}
/**
* Increments a string.
*
* @param s string to increment
* @return incremented string
*/
private String incrementString(String s) {
StringBuffer in = new StringBuffer(s);
int pos = in.length() - 1;
while (pos >= 0) {
char c = in.charAt(pos);
if (c != 'z') {
in.setCharAt(pos, CHARS[c - 'a' + 1]);
break;
} else {
in.setCharAt(pos, 'a');
}
--pos;
}
if (pos < 0) {
return null; // no more strings
} else {
return in.toString();
}
}
/**
* Returns the start value.
*
* @return start value.
*/
public String getStartValue() {
return startValue;
}
/**
* Sets the start value
*
* @param sv The startValue to set.
*/
public void setStartValue(String sv) {
startValue = sv;
}
}
