The Store class encapsulates a client side cache of Ext.data.Record objects which provide input data for widgets such as the Ext.grid.Grid, or the Ext.form.ComboBox.
A Store object uses an implementation of Ext.data.DataProxy to access a data object unless you call loadData() directly and pass in your data. The Store object has no knowledge of the format of the data returned by the Proxy.
A Store object uses its configured implementation of Ext.data.DataReader to create Ext.data.Record instances from the data object. These records are cached and made available through accessor functions.
Store这个类包装了Ext.data.Record(Record这个类为ext.grid.grid,ext.form.combobox这些小控件提供数据库)
Store用实现了ext.data.dataproxy的类去访问数据对象，除非你直接使用loadData()去访问你的数据，Store并不知道Proxy的返回格式
Store使用实现了ext.data.datareader的配置从数据源产生ext.data.record实例，