xtype：在EXTJS的可視化組件部署中的一種機制，即通過指定xtype的值，來告訴容量如何初始化所包含的級件，如xtype:"textfiled",表示使用Ext.form.TextFile來進行初始化當前組件。
xtype Class ------------- ------------------ box Ext.BoxComponentbutton Ext.Buttonbuttongroup Ext.ButtonGroupcolorpalette Ext.ColorPalettecomponent Ext.Componentcontainer Ext.Containercycle Ext.CycleButtondataview Ext.DataViewdatepicker Ext.DatePickereditor Ext.Editoreditorgrid Ext.grid.EditorGridPanelflash Ext.FlashComponentgrid Ext.grid.GridPanellistview Ext.ListViewpanel Ext.Panelprogress Ext.ProgressBarpropertygrid Ext.grid.PropertyGridslider Ext.Sliderspacer Ext.Spacersplitbutton Ext.SplitButtontabpanel Ext.TabPaneltreepanel Ext.tree.TreePanelviewport Ext.ViewPortwindow Ext.WindowToolbar components --------------------------------------- paging Ext.PagingToolbartoolbar Ext.Toolbartbbutton Ext.Toolbar.Button (deprecated; use button) tbfill Ext.Toolbar.Filltbitem Ext.Toolbar.Itemtbseparator Ext.Toolbar.Separatortbspacer Ext.Toolbar.Spacertbsplit Ext.Toolbar.SplitButton (deprecated; use splitbutton) tbtext Ext.Toolbar.TextItemMenu components --------------------------------------- menu Ext.menu.Menucolormenu Ext.menu.ColorMenudatemenu Ext.menu.DateMenumenubaseitem Ext.menu.BaseItemmenucheckitem Ext.menu.CheckItemmenuitem Ext.menu.Itemmenuseparator Ext.menu.Separatormenutextitem Ext.menu.TextItemForm components --------------------------------------- form Ext.FormPanelcheckbox Ext.form.Checkboxcheckboxgroup Ext.form.CheckboxGroupcombo Ext.form.ComboBoxdatefield Ext.form.DateFielddisplayfield Ext.form.DisplayFieldfield Ext.form.Fieldfieldset Ext.form.FieldSethidden Ext.form.Hiddenhtmleditor Ext.form.HtmlEditorlabel Ext.form.Labelnumberfield Ext.form.NumberFieldradio Ext.form.Radioradiogroup Ext.form.RadioGrouptextarea Ext.form.TextAreatextfield Ext.form.TextFieldtimefield Ext.form.TimeFieldtrigger Ext.form.TriggerFieldChart components --------------------------------------- chart Ext.chart.Chartbarchart Ext.chart.BarChartcartesianchart Ext.chart.CartesianChartcolumnchart Ext.chart.ColumnChartlinechart Ext.chart.LineChartpiechart Ext.chart.PieChartStore xtypes --------------------------------------- arraystore Ext.data.ArrayStoredirectstore Ext.data.DirectStoregroupingstore Ext.data.GroupingStorejsonstore Ext.data.JsonStoresimplestore Ext.data.SimpleStore (deprecated; use arraystore) store Ext.data.Storexmlstore Ext.data.XmlStore
defaults：xtypes的默認值，如：
defaults:{xtype:"textfield",width:180}, items:[{fieldLabel:"帳號"},{fieldLabel:"密碼"}],