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Spring Framework example source code file (AbstractRoutingDataSource.java)

This example Spring Framework source code file (AbstractRoutingDataSource.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Spring Framework tags/keywords

connection, datasource, datasource, illegal, illegalargumentexception, illegalargumentexception, initializingbean, jdbc, jndidatasourcelookup, map, object, object, sql, sqlexception, string, string, util

The Spring Framework AbstractRoutingDataSource.java source code

/*
 * Copyright 2002-2008 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.datasource.lookup;

import java.sql.Connection;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

import javax.sql.DataSource;

import org.springframework.beans.factory.InitializingBean;
import org.springframework.jdbc.datasource.AbstractDataSource;
import org.springframework.util.Assert;

/**
 * Abstract {@link javax.sql.DataSource} implementation that routes {@link #getConnection()}
 * calls to one of various target DataSources based on a lookup key. The latter is usually
 * (but not necessarily) determined through some thread-bound transaction context.
 *
 * @author Juergen Hoeller
 * @since 2.0.1
 * @see #setTargetDataSources
 * @see #setDefaultTargetDataSource
 * @see #determineCurrentLookupKey()
 */
public abstract class AbstractRoutingDataSource extends AbstractDataSource implements InitializingBean {

	private Map targetDataSources;

	private Object defaultTargetDataSource;

	private DataSourceLookup dataSourceLookup = new JndiDataSourceLookup();

	private Map resolvedDataSources;

	private DataSource resolvedDefaultDataSource;


	/**
	 * Specify the map of target DataSources, with the lookup key as key.
	 * The mapped value can either be a corresponding {@link javax.sql.DataSource}
	 * instance or a data source name String (to be resolved via a
	 * {@link #setDataSourceLookup DataSourceLookup}).
	 * <p>The key can be of arbitrary type; this class implements the
	 * generic lookup process only. The concrete key representation will
	 * be handled by {@link #resolveSpecifiedLookupKey(Object)} and
	 * {@link #determineCurrentLookupKey()}.
	 */
	public void setTargetDataSources(Map targetDataSources) {
		this.targetDataSources = targetDataSources;
	}

	/**
	 * Specify the default target DataSource, if any.
	 * The mapped value can either be a corresponding {@link javax.sql.DataSource}
	 * instance or a data source name String (to be resolved via a
	 * {@link #setDataSourceLookup DataSourceLookup}).
	 * <p>This DataSource will be used as target if none of the keyed
	 * {@link #setTargetDataSources targetDataSources} match the
	 * {@link #determineCurrentLookupKey()} current lookup key.
	 */
	public void setDefaultTargetDataSource(Object defaultTargetDataSource) {
		this.defaultTargetDataSource = defaultTargetDataSource;
	}

	/**
	 * Set the DataSourceLookup implementation to use for resolving data source
	 * name Strings in the {@link #setTargetDataSources targetDataSources} map.
	 * <p>Default is a {@link JndiDataSourceLookup}, allowing the JNDI names
	 * of application server DataSources to be specified directly.
	 */
	public void setDataSourceLookup(DataSourceLookup dataSourceLookup) {
		this.dataSourceLookup = (dataSourceLookup != null ? dataSourceLookup : new JndiDataSourceLookup());
	}


	public void afterPropertiesSet() {
		if (this.targetDataSources == null) {
			throw new IllegalArgumentException("targetDataSources is required");
		}
		this.resolvedDataSources = new HashMap(this.targetDataSources.size());
		for (Iterator it = this.targetDataSources.entrySet().iterator(); it.hasNext();) {
			Map.Entry entry = (Map.Entry) it.next();
			Object lookupKey = resolveSpecifiedLookupKey(entry.getKey());
			DataSource dataSource = resolveSpecifiedDataSource(entry.getValue());
			this.resolvedDataSources.put(lookupKey, dataSource);
		}
		if (this.defaultTargetDataSource != null) {
			this.resolvedDefaultDataSource = resolveSpecifiedDataSource(this.defaultTargetDataSource);
		}
	}

	/**
	 * Resolve the specified data source object into a DataSource instance.
	 * <p>The default implementation handles DataSource instances and data source
	 * names (to be resolved via a {@link #setDataSourceLookup DataSourceLookup}).
	 * @param dataSource the data source value object as specified in the
	 * {@link #setTargetDataSources targetDataSources} map
	 * @return the resolved DataSource (never <code>null)
	 * @throws IllegalArgumentException in case of an unsupported value type
	 */
	protected DataSource resolveSpecifiedDataSource(Object dataSource) throws IllegalArgumentException {
		if (dataSource instanceof DataSource) {
			return (DataSource) dataSource;
		}
		else if (dataSource instanceof String) {
			return this.dataSourceLookup.getDataSource((String) dataSource);
		}
		else {
			throw new IllegalArgumentException(
					"Illegal data source value - only [javax.sql.DataSource] and String supported: " + dataSource);
		}
	}


	public Connection getConnection() throws SQLException {
		return determineTargetDataSource().getConnection();
	}

	public Connection getConnection(String username, String password) throws SQLException {
		return determineTargetDataSource().getConnection(username, password);
	}

	/**
	 * Retrieve the current target DataSource. Determines the
	 * {@link #determineCurrentLookupKey() current lookup key}, performs
	 * a lookup in the {@link #setTargetDataSources targetDataSources} map,
	 * falls back to the specified
	 * {@link #setDefaultTargetDataSource default target DataSource} if necessary.
	 * @see #determineCurrentLookupKey()
	 */
	protected DataSource determineTargetDataSource() {
		Assert.notNull(this.resolvedDataSources, "DataSource router not initialized");
		Object lookupKey = determineCurrentLookupKey();
		DataSource dataSource = (DataSource) this.resolvedDataSources.get(lookupKey);
		if (dataSource == null) {
			dataSource = this.resolvedDefaultDataSource;
		}
		if (dataSource == null) {
			throw new IllegalStateException("Cannot determine target DataSource for lookup key [" + lookupKey + "]");
		}
		return dataSource;
	}


	/**
	 * Resolve the given lookup key object, as specified in the
	 * {@link #setTargetDataSources targetDataSources} map, into
	 * the actual lookup key to be used for matching with the
	 * {@link #determineCurrentLookupKey() current lookup key}.
	 * <p>The default implementation simply returns the given key as-is.
	 * @param lookupKey the lookup key object as specified by the user
	 * @return the lookup key as needed for matching
	 */
	protected Object resolveSpecifiedLookupKey(Object lookupKey) {
		return lookupKey;
	}

	/**
	 * Determine the current lookup key. This will typically be
	 * implemented to check a thread-bound transaction context.
	 * <p>Allows for arbitrary keys. The returned key needs
	 * to match the stored lookup key type, as resolved by the
	 * {@link #resolveSpecifiedLookupKey} method.
	 */
	protected abstract Object determineCurrentLookupKey();

}

Other Spring Framework examples (source code examples)

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