1：在WEB工程SEC目录下新建一个database.properties文件，里面保存连接数据库信息
2：public class DBUtil {
   private String driver;
   private String url;
   private String user;
   private String psw;
   private static DBUtil dbutil=null;
   private DBUtil() throws IOException, ClassNotFoundException{
	   InputStream is=this.getClass().getClassLoader().getResourceAsStream("database.properties");
	   Properties p=new Properties();
	   p.load(is);
	   driver=p.getProperty("driver");
	   url=p.getProperty("url");
	   user=p.getProperty("user");
	   psw=p.getProperty("psw");	   
	   Class.forName(driver);
   }
   /**
	 * 获得数据库帮助类唯一实例
	 */
  synchronized public static DBUtil getInstance() throws IOException, ClassNotFoundException{
	   if(dbutil==null){
		   dbutil=new DBUtil();
	   }
	   return dbutil;
   }
  /**
	 * 获取数据库连接 无参数
	 */
 
  synchronized public Connection getConnection() throws SQLException{
	  return DriverManager.getConnection(url,user,psw);
  }