org.apache.mahout.cf.taste.impl.common.jdbc.AbstractJDBCComponent Maven / Gradle / Ivy
/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.mahout.cf.taste.impl.common.jdbc;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.sql.DataSource;
import org.apache.mahout.cf.taste.common.TasteException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.google.common.base.Preconditions;
/**
* A helper class with common elements for several JDBC-related components.
*/
public abstract class AbstractJDBCComponent {
private static final Logger log = LoggerFactory.getLogger(AbstractJDBCComponent.class);
private static final int DEFAULT_FETCH_SIZE = 1000; // A max, "big" number of rows to buffer at once
protected static final String DEFAULT_DATASOURCE_NAME = "jdbc/taste";
protected static void checkNotNullAndLog(String argName, Object value) {
Preconditions.checkArgument(value != null && !value.toString().isEmpty(),
argName + " is null or empty");
log.debug("{}: {}", argName, value);
}
protected static void checkNotNullAndLog(String argName, Object[] values) {
Preconditions.checkArgument(values != null && values.length != 0, argName + " is null or zero-length");
for (Object value : values) {
checkNotNullAndLog(argName, value);
}
}
/**
*
* Looks up a {@link DataSource} by name from JNDI. "java:comp/env/" is prepended to the argument before
* looking up the name in JNDI.
*
*
* @param dataSourceName
* JNDI name where a {@link DataSource} is bound (e.g. "jdbc/taste")
* @return {@link DataSource} under that JNDI name
* @throws TasteException
* if a JNDI error occurs
*/
public static DataSource lookupDataSource(String dataSourceName) throws TasteException {
Context context = null;
try {
context = new InitialContext();
return (DataSource) context.lookup("java:comp/env/" + dataSourceName);
} catch (NamingException ne) {
throw new TasteException(ne);
} finally {
if (context != null) {
try {
context.close();
} catch (NamingException ne) {
log.warn("Error while closing Context; continuing...", ne);
}
}
}
}
protected int getFetchSize() {
return DEFAULT_FETCH_SIZE;
}
}