/*
* Copyright 2002-2006 the original author or authors.
*
* Licensed 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.springframework.jdbc.core.support;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Properties;
import javax.sql.DataSource;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.PropertiesBeanDefinitionReader;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowCallbackHandler;
import org.springframework.util.Assert;
/**
* Bean definition reader that reads values from a database table,
* based on a given SQL statement.
*
* <p>Expects columns for bean name, property name and value as String.
* Formats for each are identical to the properties format recognized
* by PropertiesBeanDefinitionReader.
*
* <p><b>NOTE:</b> This is mainly intended as an example for a custom
* JDBC-based bean definition reader. It does not aim to offer
* comprehensive functionality.
*
* @author Rod Johnson
* @author Juergen Hoeller
* @see #loadBeanDefinitions
* @see org.springframework.beans.factory.support.PropertiesBeanDefinitionReader
*/
public class JdbcBeanDefinitionReader {
private final PropertiesBeanDefinitionReader propReader;
private JdbcTemplate jdbcTemplate;
/**
* Create a new JdbcBeanDefinitionReader for the given bean factory,
* using a default PropertiesBeanDefinitionReader underneath.
* <p>DataSource or JdbcTemplate still need to be set.
* @see #setDataSource
* @see #setJdbcTemplate
*/
public JdbcBeanDefinitionReader(BeanDefinitionRegistry beanFactory) {
this.propReader = new PropertiesBeanDefinitionReader(beanFactory);
}
/**
* Create a new JdbcBeanDefinitionReader that delegates to the
* given PropertiesBeanDefinitionReader underneath.
* <p>DataSource or JdbcTemplate still need to be set.
* @see #setDataSource
* @see #setJdbcTemplate
*/
public JdbcBeanDefinitionReader(PropertiesBeanDefinitionReader beanDefinitionReader) {
Assert.notNull(beanDefinitionReader, "Bean definition reader must not be null");
this.propReader = beanDefinitionReader;
}
/**
* Set the DataSource to use to obtain database connections.
* Will implicitly create a new JdbcTemplate with the given DataSource.
*/
public void setDataSource(DataSource dataSource) {
this.jdbcTemplate = new JdbcTemplate(dataSource);
}
/**
* Set the JdbcTemplate to be used by this bean factory.
* Contains settings for DataSource, SQLExceptionTranslator, NativeJdbcExtractor, etc.
*/
public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {
Assert.notNull(jdbcTemplate, "JdbcTemplate must not be null");
this.jdbcTemplate = jdbcTemplate;
}
/**
* Load bean definitions from the database via the given SQL string.
* @param sql SQL query to use for loading bean definitions.
* The first three columns must be bean name, property name and value.
* Any join and any other columns are permitted: e.g.
* <code>SELECT BEAN_NAME, PROPERTY, VALUE FROM CONFIG WHERE CONFIG.APP_ID = 1</code>
* It's also possible to perform a join. Column names are not significant --
* only the ordering of these first three columns.
*/
public void loadBeanDefinitions(String sql) {
Assert.notNull(this.jdbcTemplate, "Not fully configured - specify DataSource or JdbcTemplate");
final Properties props = new Properties();
this.jdbcTemplate.query(sql, new RowCallbackHandler() {
public void processRow(ResultSet rs) throws SQLException {
String beanName = rs.getString(1);
String property = rs.getString(2);
String value = rs.getString(3);
// Make a properties entry by combining bean name and property.
props.setProperty(beanName + "." + property, value);
}
});
this.propReader.registerBeanDefinitions(props);
}
}
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