Struts2+EXTJS+JSON为什么我得到的值不显示？

[詩人的眼淚]

最近做ExtJS，遇到一个问题，就是我发送请求可以返回字符串，但是我的前台却显示不出来，也不报错，请大家帮我看看是怎么回事，先谢谢了。

这个是我的Action类关键代码：

@Override
	public String execute() throws Exception {
		// TODO Auto-generated method stub
		System.out.println("获取到请求");
		String msg = ExtHelper.getJsonFromList(manager.search());
		System.out.println("msg:"+msg);
		ServletActionContext.getResponse().getWriter().write(msg);
		return null;
	}

下面是我工具类，封装Json数据的代码：

	/**
	 * 将List集合解析成JSON数据
	 * @param list
	 * @return
	 */
	public static String getJsonFromList(List list){
		TotalJson totalJson = new TotalJson();
		totalJson.setItems(list);
		totalJson.setTotal(list.size());
		JSONObject object = JSONObject.fromObject(totalJson);
		return object.toString();
	}

封装后的Json数据是这个样子：
{"items":[{"address":"1","id":1,"name":"1"},{"address":"2","id":2,"name":"2"},{"address":"3","id":3,"name":"3"},{"address":"4","id":4,"name":"4"},{"address":"5","id":5,"name":"5"},{"address":"6","id":6,"name":"6"},{"address":"7","id":7,"name":"7"},{"address":"8","id":8,"name":"8"},{"address":"9","id":9,"name":"9"}],"total":9}

下面是前台页面代码：

Ext.onReady(function(){
            
		var store = new Ext.data.Store({
		        autoLoad: true,
		
		        proxy: new Ext.data.ScriptTagProxy({
		            url: 'student'
		        }),
		
		        reader: new Ext.data.JsonReader({
		            root: 'items',
		            totalProperty: 'total',
		            idProperty: 'id',
		            fields: [
		                {name:'id'},
		                {name: 'name'},
		                {name: 'address'}
		            ]
		        })
		    });
		
		    var grid = new Ext.grid.GridPanel({
		        renderTo: 'grid-div',
		        width:700,
		        height:600,
		        frame:true,
		        stripeRows:true,
		        title:'<center>***管理</center>',
		        store: store,
		
		        columns: [new Ext.grid.RowNumberer({width: 30}),{
		            id: 'id',
		            header: "编号",
		            dataIndex: 'id',
		            width: 420,
		            sortable:true
		        },{
		            header: "姓名",
		            dataIndex: 'name',
		            width: 70,
		            align: 'right',
		            sortable:true
		        },{
		            id: 'address',
		            header: "地址",
		            dataIndex: 'adress',
		            width: 150,
		            sortable:true
		        }],
		
			    bbar: new Ext.PagingToolbar({
				    store: store,
				    pageSize:20,
				    displayInfo:true
			    })
		    });
		
		
			
		});

调试出来之后，也不报错，什么也不显示，请各位大哥帮我看看这是什么原因.

[flyerwing]

估计是JS错了,或者是返回数据格式不对.