ext中ComboBox的简单用法

下面是：ext中ComboBox的简单用法

//comboBox的数据源，仓库信息
    var dsSupplier = new Ext.data.Store({
        proxy: new Ext.data.HttpProxy({
           url:getRootPath()+'servlet/ProduceTaskServlet?change=sStore'
        }),
        reader: new Ext.data.JsonReader({
        	root: 'gridRows',
        	totalProperty: 'totalCount'
        }, [
        	{name: 'STOREID'},
           {name: 'NAME'}
           
        ])
    });
    var combo=new fm.ComboBox({
    	store:dsSupplier,
    	fieldLabel: '仓库',
    	typeAhead: true,
        triggerAction: 'all',
        lazyRender: true,
        listClass: 'x-combo-list-small',
        valueField:'STOREID',
        displayField:'NAME'
    });
    var form=new fm.FormPanel({
    	labelAlign:'right',
    	labelWidth:50,
    	frame:true,
    	defaultType:'comboBox',
    	items:[combo]
    });
    var win =new Ext.Window({
    	//renderTo: 'window-win',
    	layout:'fit',
    	modal : true,
    	width:500,
    	height:300,
    	closeAction:'hide',
    	items:[form],
    	buttons:[{
    		text:'生成出库单',
    		listeners:{
                    click:function(){
                	 alert("ssssss"+Ext.get('STOREID'));
                     }
               }
    		
    	}]
    });

 后台的数据源  是用servlet表现的。。json格式

response.setContentType("text/xml;charset=UTF-8");
response.setHeader("Cache-Control", "no-cache");
String change=request.getParameter("change");
        
JSONObject json=new JSONObject();
JSONArray array = new JSONArray();
ProduceTask pt=new ProduceTask();
Resultobj rt=null;
PrintWriter out = response.getWriter();
if(change.equals("sStore")){
        	String cgid=(String)request.getSession().getAttribute("CGID");
        	try {
				rt=pt.searchStore(cgid);
				if(rt.Rows>0){
					for(int i=1;i<rt.Rows;i++){
						 Map<String, Object> map1 = new HashMap<String, Object>();
		    	         map1.put("STOREID", rt.getCell("STOREID", i));
		    	         map1.put("NAME", rt.getCell("NAME", i));
		    	         array.put(map1);
					 }
					json.put("gridRows", array);
					json.put("totalCount", array.length());
					
			         out.print(json);
			         out.close();
				}
			} catch (GeneralException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}catch (JSONException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
        }

 这个项目中需要导入json的jar包