dbsetting.java

本文论述了一个前台笔记本销售系统的开发过程

package com.set.db;

import java.util.Properties;

import org.apache.log4j.Logger;

import com.set.db.dialect.Dialect;

/**
 * configuration that reads a property file named "dbaccess.properties" in class
 * path
 * 
 * @author tommy.zeng
 * 
 */
public class DBSetting {
	private Dialect dialect;

	private static boolean loaded = false;

	private boolean isScrollableResultSetsEnabled = true;

	private static DBSetting instance = null;

	private static Logger logger = Logger.getLogger(DBSetting.class);

	private DBSetting() {
		try {
			load("dbaccess.properties");
		} catch (Exception ex) {
			logger.error(ex);
		}
	}

	public static DBSetting getInstance() {
		if (null == instance)
			instance = new DBSetting();
		return instance;
	}

	public void load(String source) throws Exception {
		if (!loaded) {
			Properties p = new Properties();
			p
					.load(DBSetting.class.getClassLoader().getResourceAsStream(
							source));
			String dia = p.getProperty("dialect");
			if (null != dia) {
				try {
					dialect = (Dialect) Class.forName(dia).newInstance();
					isScrollableResultSetsEnabled = "true".equals(p
							.getProperty("isScrollableResultSetsEnabled"));
				} catch (Exception ex) {
					logger.error(ex);
				}
			}
			loaded = true;
		}
	}

	public void reload(String source) throws Exception {
		loaded = false;
		load(source);
	}

	public Dialect getDialect() {
		return dialect;
	}

	public void setDialect(Dialect dialect) {
		this.dialect = dialect;
	}

	public boolean isScrollableResultSetsEnabled() {
		return this.isScrollableResultSetsEnabled;
	}

}