Extjs 4.2 动态加载checkboxgroup

List<Risinstrumenttype> instrulist = Webimpl.getInstance().queryInstrumenttype();
String type = JsonUtil.list2json(instrulist);
json = "{items:" + type + "}";
//System.out.println(json);
response.getWriter().write(json);

{items:[{"typeid":"1001","typename":"CT"},{"typeid":"1001","typename":"CT"}]}

Ext.Ajax.request({
url: 'showinstrument.do',//请求的地址。
callback: function(options, success, response) {
if (success === true) {
var obj = eval("(" + response.responseText + ")");
//拼接checkbox子项目
var checkboxitems = "";
for (var i = 0; i < obj.items.length; i++) {
if (checkboxitems !== "")
checkboxitems += ",";
else
checkboxitems += "[";
var typename = obj.items[i].typename;
var checkboxSingleItem = "{boxLabel:'" + typename + "',name:'instrumentkind',inputValue:'" + typename + "'";

　　　　　　　　checkboxSingleItem += "}";
//                    alert(checkboxSingleItem);
checkboxitems += checkboxSingleItem;
}
checkboxitems += "]";
//                alert(checkboxitems);
var itemsGroup = new Ext.form.CheckboxGroup({
x: 10,
y: 120,
width: 845,
fieldLabel: '种类',
id: 'instrumentkind',
disabled: true,
labelWidth: 70,
items: eval(checkboxitems)
});

Ext.getCmp('form1').add(itemsGroup); //这个是根据ID，添加到你想要显示的那个from下。
Ext.getCmp('form1').doLayout();//好象是，重新刷新那个form，原理我也不清楚。

}
}
});