ExtJS Grid使用SimpleStore、多选框的方法

///<reference path="./vswd-ext_2.0.2.js" /> 
Ext.onReady(function(){ 
var data = [ 
[1,"wilson.fu",10], 
[2,"wilson.fu2",20], 
[3,"wilson.fu3",30] 
]; var sqldata = new Array() ; 
for(var i=0;i<10;i++) 
{ 
sqldata.push([i.toString(),"wilson.fu" + i.toString(),10*i]); 
} 
var sm = new Ext.grid.CheckboxSelectionModel({handleMouseDown:Ext.emptyFn}); 
var cm = new Ext.grid.ColumnModel([ 
sm, 
{header:"编号",dataIndex:"id",sortable:true}, 
{header:"姓名",dataIndex:"name"}, 
{header:"排序值",dataIndex:"ordernum",sortable:true} 
]); 
var store = new Ext.data.SimpleStore({ 
fields:[ 
{name:"id"}, 
{name:"name"}, 
{name:"ordernum"} 
] 
}); 
store.loadData(sqldata); 
var gd = new Ext.grid.GridPanel({ 
renderTo:"grid", 
cm:cm, 
sm:sm, 
store:store, 
loadMask:true 
}); 
Ext.get("btn").on("click",function(){ 
var selections = gd.getSelectionModel().getSelections(); 
debugger 
//得到选择的行的值 
}); 
});