ScriptTagProxy+XTemplate+WCF跨域取數據

ajax應用中跨域一直是一個非常麻煩的問題，目前也有一些解決辦法，但要么比較麻煩，要么就不具備通用性，幸好ExtJs里的ScriptTagProxy提供了跨域讀取數據的功能，而且在幾大瀏覽器上都可以正常運行，但在使用過程中要注意幾點:

1.服務端返回時，必須按以下格式返回:

stcCallback1001({...})

其中stcCallback1001中的1001是自動生成的，如果是分頁提交的話，每再請求一次1001會變成1002,1003...類推

2.ExtJs官方的示例中雖然ScriptTagProxy的例子并不少，但是就是沒有XTemplate+ScriptTagProxy跨域讀取的單一功能示例，下面給一個XTemplate跨域讀取數據的示例

a.服務端WCF的處理

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);//為演示Ajax加載效果，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 = "這是第一條留言", F_Reply = "" });
        _List.Add(new T_GuestBook() { F_ID = 2, F_IP = "192.168.0.1", F_Date = DateTime.Now, F_Content = "這是第二條留言", F_Reply = "" });
        _List.Add(new T_GuestBook() { F_ID = 3, F_IP = "192.168.0.2", F_Date = DateTime.Now, F_Content = "這是第三條留言", F_Reply = "" });
        _List.Add(new T_GuestBook() { F_ID = 4, F_IP = "172.168.235.1", F_Date = DateTime.Now, F_Content = "這是第四條留言", F_Reply = "" });
        _List.Add(new T_GuestBook() { F_ID = 5, F_IP = "10.200.30.4", F_Date = DateTime.Now, F_Content = "這是第五條留言", F_Reply = "" });
        _List.Add(new T_GuestBook() { F_ID = 6, F_IP = "10.200.30.5", F_Date = DateTime.Now, F_Content = "這是第六條留言", F_Reply = "" });
        //以上操作也可以改為利用Linq直接從數據庫讀取                   


        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;

        //計算總頁數
        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();//取得當前頁數據

        _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;
    }

這里與上一篇http://www.cnblogs.com/yjmyzz/archive/2008/09/10/1288399.html (ExtJs學習筆記(22)-XTemplate + WCF 打造無刷新數據分頁)相比，多了一個參數callBack，同時返回類型改為Stream，返回方法的處理參考了老張的(再說ExtJs與WCF之間的跨域訪問)一文

b.ExtJs的前端處理

Code




    
    
    
    
        







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這里要注意的是:

嘗試了多次，發現XTemplate不支持多層節點的綁定，即服務端返回的值類似：

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":"這是第三條留言","F_Reply":""},{"F_ID":4,"F_IP":"172.168.235.1","F_Date":new Date(1221399073843),"F_Content":"這是第四條留言","F_Reply":""}]})

在回調函數里經過Ext.util.JSON.encode(data)處理后，變成了

{"success":true,"records":[{"id":1001,"data":{"F_ID":3,"F_IP":"192.168.0.2","F_Date":"2008-09-14T21:28:28","F_Content":"這是第三條留言"},"json":

{"F_ID":3,"F_IP":"192.168.0.2","F_Date":"2008-09-14T21:28:28","F_Content":"這是第三條留言","F_Reply":""}},{"id":1002,"data":{"F_ID":4,"F_IP":"172.168.235.1","F_Date":"2008

-09-14T21:28:28","F_Content":"這是第四條留言"},"json":{"F_ID":4,"F_IP":"172.168.235.1","F_Date":"2008-09-14T21:28:28","F_Content":"這是第四條留

言","F_Reply":""}}],"totalRecords":6}

雖然也是標準的JSON字符串，但是數據節點是多層次的，XTemplate無法直接讀取。所以只能在客戶端用JS的正則表達式處理，手動重新組織成XTemplate所需的JSON對象，最終轉換成：

{data:[{"F_ID":3,"F_IP":"192.168.0.2","F_Date":"2008-09-14T21:29:55","F_Content":"這是第三條留言","F_Reply":""},{"F_ID":4,"F_IP":"172.168.235.1","F_Date":"2008-09-14T21:29:55","F_Content":"這是第四條留言","F_Reply":""}]}