一 Configuration类 之 1_Configuration对象
用过Hibernate的朋友都知道下面代码的意思，不知道的话，看这篇文章也没意思了！
启动代码：
Configuration cfg=new Configuration();
cfg.addClass(User.class);
cfg.configure();
SchemaExport export=new SchemaExport(cfg);
export.create(true, true);
（1）实例化一个Configuration对象
Configuration cfg=new Configuration();
--->
public Configuration() {
this( new SettingsFactory() );
}
--->
this( new SettingsFactory() );相当于调用
protected Configuration(SettingsFactory settingsFactory) {
this.settingsFactory = settingsFactory;
reset();
}
Configuration是需要将配置信息的设置委托给SettingsFactory, SettingsFactory拥有设置配置信息的方法，比如说，public Settings buildSettings(Properties props)
返回的Settings类:存放系统配置信息转换的对象,比如从Properties得到的信息，转换成对象，然后存入Settings对象。
（注意：settings是Settings类对象，props是Properties类对象）
String sessionFactoryName = props.getProperty(Environment.SESSION_FACTORY_NAME);
settings.setSessionFactoryName(sessionFactoryName);
Configuration只做自己应该做的事情就是从properties *.cfg.xml读取系统的参数.
---> protected void reset() {
classes = new HashMap();
imports = new HashMap();
collections = new HashMap();
tables = new TreeMap();
namedQueries = new HashMap();
namedSqlQueries = new HashMap();
sqlResultSetMappings = new HashMap();
xmlHelper = new XMLHelper();
typeDefs = new HashMap();
propertyReferences = new ArrayList();
secondPasses = new ArrayList();
interceptor = EmptyInterceptor.INSTANCE;
properties = Environment.getProperties();
entityResolver = XMLHelper.DEFAULT_DTD_RESOLVER;
eventListeners = new EventListeners();
filterDefinitions = new HashMap();
//extendsQueue = new ArrayList();
extendsQueue = new HashMap();
auxiliaryDatabaseObjects = new ArrayList();
tableNameBinding = new HashMap();
columnNameBindingPerTable = new HashMap();
namingStrategy = DefaultNamingStrategy.INSTANCE;
sqlFunctions = new HashMap();
}
reset()：
除了申请一些HashMap对象，ArrayList对象，TreeMap对象，用来存放XML解释后的信息外，还有XMLHelper用于帮助读取XML，
EmptyInterceptor用于扩展自定义拦截器。
EventListeners，一个支持对所有session事件的监听器
DefaultNamingStrategy，默认的命名策略。
还有最重要的
properties = Environment.getProperties();
关键是初始化hibernate.properties文件的信息.
