com.googlecode.wmbutil.jdbc.DataSourceLocator.java Source code

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Here is the source code for com.googlecode.wmbutil.jdbc.DataSourceLocator.java

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/*
 * Copyright 2007 (C) Callista Enterprise.
 * 
 * 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 com.googlecode.wmbutil.jdbc;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;

import javax.sql.DataSource;

import org.apache.commons.dbcp.BasicDataSource;

/**
 * Used for looking up JDBC data sources at runtime. Uses a file for storing the
 * data source configuration. The file is loaded from the Message Broker
 * workpath using a file that must be named "jdbc-connections.properties". For
 * each named data source, the file must contain the following properties (in a
 * typical Java properties file):
 * <ul>
 * <li>jdbc.<data source name>.class - the class name for the JDBC driver</li>
 * <li>jdbc.<data source name>.url - JDBC URL for the database</li>
 * <li>jdbc.<data source name>.username - the username used to connect to the
 * database</li>
 * <li>jdbc.<data source name>.password - the password used to connect to the
 * database</li>
 * </ul>
 */
public class DataSourceLocator {

    private static final DataSourceLocator instance = new DataSourceLocator();

    public static DataSourceLocator getInstance() {
        return instance;
    }

    private DataSourceLocator() {
        String brokerWorkpathPath = System.getProperty("broker.workpath");

        if (brokerWorkpathPath == null) {
            throw new IllegalStateException("System property broker.workpath must be set");
        }

        File brokerWorkpath = new File(brokerWorkpathPath);
        File configFile = new File(brokerWorkpath, "jdbc-connections.properties");

        if (configFile.exists()) {
            config = new Properties();
            try {
                FileInputStream fs = new FileInputStream(configFile);
                config.load(fs);
                fs.close();
            } catch (IOException e) {
                throw new RuntimeException("Failed to read lookup connections configuration file at "
                        + configFile.getAbsolutePath() + ". Missing permissions?");
            }
        } else {
            throw new RuntimeException(
                    "JDBC connections configuration file does not exist at " + configFile.getAbsolutePath());
        }

    }

    private Properties config;
    private Map dataSources = new HashMap();

    /**
     * Looks up a named data source
     * 
     * @param dataSourceName
     *            The name of the data source to look for
     * @return The data source
     * @throws RuntimeException
     *             If the configuration can not be loaded or the data source
     *             definition is missing
     */
    public synchronized DataSource lookup(String dataSourceName) {
        BasicDataSource ds;
        if (dataSources.containsKey(dataSourceName)) {
            ds = (BasicDataSource) dataSources.get(dataSourceName);

            if (ds == null) {
                // we failed to create it earlier
                throw new RuntimeException("Failed to create data source");
            }
        } else {
            ds = new BasicDataSource();

            try {
                String driver = config.getProperty("jdbc." + dataSourceName + ".class");
                if (driver == null || driver.trim().length() == 0) {
                    throw new RuntimeException("Lookup connections configuration file must contain a jdbc."
                            + dataSourceName + ".class value");
                } else {
                    ds.setDriverClassName(driver);
                }

                String url = config.getProperty("jdbc." + dataSourceName + ".url");
                if (url == null || url.trim().length() == 0) {
                    throw new RuntimeException("Lookup connections configuration file must contain a jdbc."
                            + dataSourceName + ".url value");
                } else {
                    ds.setUrl(url);
                }

                String username = config.getProperty("jdbc." + dataSourceName + ".username");
                if (username == null || username.trim().length() == 0) {
                    throw new RuntimeException("Lookup connections configuration file must contain a jdbc."
                            + dataSourceName + ".username value");
                } else {
                    ds.setUsername(username);
                }

                ds.setPassword(config.getProperty("jdbc." + dataSourceName + ".password"));
                ds.setDefaultReadOnly(true);

                dataSources.put(dataSourceName, ds);
            } catch (RuntimeException e) {
                // mark failed to create
                dataSources.put(dataSourceName, null);
                throw e;
            }
        }

        return ds;

    }
}