ScriptTagProxy+XTemplate+WCF跨域取数据

ajax应用中跨域一直是一个非常麻烦的问题，目前也有一些解决办法，但要么比较麻烦，要么就不具备通用性，幸好ExtJs里的ScriptTagProxy提供了跨域读取数据的功能，而且在几大浏览器上都可以正常运行，但在使用过程中要注意几点:

1.服务端返回时，必须按以下格式返回:

stcCallback1001({...})

其中stcCallback1001中的1001是自动生成的，如果是分页提交的话，每再请求一次1001会变成1002,1003...类推

2.ExtJs官方的示例中虽然ScriptTagProxy的例子并不少，但是就是没有XTemplate+ScriptTagProxy跨域读取的单一功能示例，下面给一个XTemplate跨域读取数据的示例

a.服务端WCF的处理

Code
[OperationContract]
    [WebInvoke(ResponseFormat = WebMessageFormat.Json, UriTemplate = "GetData3?start={start}&limit={limit}&callback={callback}", Method = "*")]
    public Stream GetData3(int start, int limit,string CallBack)
    {
        System.Threading.Thread.Sleep(1000);//为演示Ajax加载效果，停1秒

        List _List = new List();
        _List.Add(new T_GuestBook() { F_ID = 1, F_IP = "192.23.37.41", F_Date = DateTime.Now, F_Content = "这是第一条留言", F_Reply = "" });
        _List.Add(new T_GuestBook() { F_ID = 2, F_IP = "192.168.0.1", F_Date = DateTime.Now, F_Content = "这是第二条留言", F_Reply = "" });
        _List.Add(new T_GuestBook() { F_ID = 3, F_IP = "192.168.0.2", F_Date = DateTime.Now, F_Content = "这是第三条留言", F_Reply = "" });
        _List.Add(new T_GuestBook() { F_ID = 4, F_IP = "172.168.235.1", F_Date = DateTime.Now, F_Content = "这是第四条留言", F_Reply = "" });
        _List.Add(new T_GuestBook() { F_ID = 5, F_IP = "10.200.30.4", F_Date = DateTime.Now, F_Content = "这是第五条留言", F_Reply = "" });
        _List.Add(new T_GuestBook() { F_ID = 6, F_IP = "10.200.30.5", F_Date = DateTime.Now, F_Content = "这是第六条留言", F_Reply = "" });
        //以上操作也可以改为利用Linq直接从数据库读取                   


        PageData> _PageData = new PageData>();

        _PageData.RecordCount = _List.Count;

        int PageSize = limit;

        if (PageSize <= 0) { PageSize = 1; }
        if (PageSize > _PageData.RecordCount) { PageSize = _PageData.RecordCount; }
        _PageData.PageSize = PageSize;

        //计算总页数
        if (_PageData.RecordCount % _PageData.PageSize == 0)
        {
            _PageData.PageCount = (_PageData.RecordCount / _PageData.PageSize);
        }
        else
        {
            _PageData.PageCount = (_PageData.RecordCount / _PageData.PageSize) + 1;
        }

        int PageIndex = (start/limit) + 1;

        if (PageIndex <= 0) { PageIndex = 1; }
        if (PageIndex > _PageData.PageCount) { PageIndex = _PageData.PageCount; }

        _PageData.CurrentPageIndex = PageIndex;

        List _List2 = _List.Skip(start).Take(limit).ToList();//取得当前页数据

        _PageData.Data = _List2;


        string returnStr = CallBack + "(" + JavaScriptConvert.SerializeObject(_PageData) +")";
        MemoryStream ms = new MemoryStream();
        StreamWriter sw = new StreamWriter(ms);
        sw.AutoFlush = true;
        sw.Write(returnStr);
        ms.Position = 0;
        WebOperationContext.Current.OutgoingResponse.ContentType = "text/plain";

        return ms;
    }

这里与上一篇http://www.cnblogs.com/yjmyzz/archive/2008/09/10/1288399.html (ExtJs学习笔记(22)-XTemplate + WCF 打造无刷新数据分页)相比，多了一个参数callBack，同时返回类型改为Stream，返回方法的处理参考了老张的(再说ExtJs与WCF之间的跨域访问)一文

b.ExtJs的前端处理

Code




    
    
    
    
        

这里要注意的是:

尝试了多次，发现XTemplate不支持多层节点的绑定，即服务端返回的值类似：

stcCallback1001({"RecordCount":6,"PageSize":2,"PageCount":3,"CurrentPageIndex":2,"Data":[{"F_ID":3,"F_IP":"192.168.0.2","F_Date":new Date(1221399073843),"F_Content":"这是第三条留言","F_Reply":""},{"F_ID":4,"F_IP":"172.168.235.1","F_Date":new Date(1221399073843),"F_Content":"这是第四条留言","F_Reply":""}]})

在回调函数里经过Ext.util.JSON.encode(data)处理后，变成了

{"success":true,"records":[{"id":1001,"data":{"F_ID":3,"F_IP":"192.168.0.2","F_Date":"2008-09-14T21:28:28","F_Content":"这是第三条留言"},"json":

{"F_ID":3,"F_IP":"192.168.0.2","F_Date":"2008-09-14T21:28:28","F_Content":"这是第三条留言","F_Reply":""}},{"id":1002,"data":{"F_ID":4,"F_IP":"172.168.235.1","F_Date":"2008

-09-14T21:28:28","F_Content":"这是第四条留言"},"json":{"F_ID":4,"F_IP":"172.168.235.1","F_Date":"2008-09-14T21:28:28","F_Content":"这是第四条留

言","F_Reply":""}}],"totalRecords":6}

虽然也是标准的JSON字符串，但是数据节点是多层次的，XTemplate无法直接读取。所以只能在客户端用JS的正则表达式处理，手动重新组织成XTemplate所需的JSON对象，最终转换成：

{data:[{"F_ID":3,"F_IP":"192.168.0.2","F_Date":"2008-09-14T21:29:55","F_Content":"这是第三条留言","F_Reply":""},{"F_ID":4,"F_IP":"172.168.235.1","F_Date":"2008-09-14T21:29:55","F_Content":"这是第四条留言","F_Reply":""}]}