URL也有长度限制？

微软说："Maximum URL length is 2,083 characters in Internet Explorer"
我们在Pricing系统开发中挑战了一下这个长度，结果以失败告终！......

问题描述：系统中通过一个QLookUp选取Vendor相关信息，包括vendor code, vendor name, vendor site, currency, trade term, ship way, tax七项信息。把处理这些信息的SQL语句和JS语句通过URL传到QLookUPSearchPage.aspx页面来查找数据时，因为URL太长而出错！

QLookUp：
简单来说，它是一个用户控件，通过URL把SQL语句和页面要执行的JS语句传到QLookUPSearchPage.aspx这个页面来查到相应的数据，并返回给调用页面。

Pricing 系统广泛并深入的应用了QLookUp控件。如下图Vendor Code。

点出来的页面如下：

因为当点选Vendor Code时还会把QLookUp查出来的数据赋给旁边的其它五个控件(Vendor Name....Ship Way)，所以它的CustomerFunction属性就会很长：

<uc1:QLookUp ID="QLookUpVendorNew" runat="server" AllowOnBlurEvent="true" OnQLookUPSelected="QLookUpVendorNew_Selected" ServiceMethod="GetVendorCodeList" CustomerFunction="if(clear!=1){objTextBoxText.value=arrayValue[1];document.getElementById('HiddenVendorIDNew').value=arrayValue[0];document.getElementById('QTextBoxVendorNameNew').value=arrayValue[2];document.getElementById('QTextBoxVendorSiteNew').value=arrayValue[3];if(arrayValue[6].length > 0){var DropDownListCurrencyNew = document.getElementById('DropDownListCurrencyNew'); for(i=0;i<DropDownListCurrencyNew.options.length;i++){if(DropDownListCurrencyNew.options[i].text==arrayValue[6]){DropDownListCurrencyNew.options[i].selected = true;}}}  if(arrayValue[4].length > 0){document.getElementById('DropDownListTradeTermNew').value=arrayValue[4];} else{document.getElementById('DropDownListTradeTermNew').options[0].selected=true;}  if(arrayValue[5].length > 0){document.getElementById('DropDownListShipWayNew').value=arrayValue[5];} else{document.getElementById('DropDownListShipWayNew').options[0].selected=true;} } else {document.getElementById('HiddenVendorIDNew').value='';document.getElementById('QTextBoxVendorNameNew').value='';document.getElementById('QTextBoxVendorSiteNew').value='';document.getElementById('DropDownListCurrencyNew').options[0].selected=true;document.getElementById('DropDownListTradeTermNew').options[0].selected=true;document.getElementById('DropDownListShipWayNew').options[0].selected=true;}" alt="required::MSG500014::QButtonAdd" TextBoxCss="QTextBox" Width="160px" WindowTitle="Select Vendor" />

为了看起来清晰点，我把CustomerFunction提出来，格式化后如下：

CustomerFunction = "

if(clear!=1)
{
    objTextBoxText.value=arrayValue[1];
    document.getElementById('HiddenVendorIDNew').value=arrayValue[0];
    document.getElementById('QTextBoxVendorNameNew').value=arrayValue[2];
    document.getElementById('QTextBoxVendorSiteNew').value=arrayValue[3];
    if(arrayValue[6].length>0)
    {
        var DropDownListCurrencyNew=document.getElementById('DropDownListCurrencyNew');
        for(i=0;i<DropDownListCurrencyNew.options.length;i++)
        {
            if(DropDownListCurrencyNew.options[i].text==arrayValue[6])
            {
                DropDownListCurrencyNew.options[i].selected=true;
                
            }
        }
    }if(arrayValue[4].length>0)
    {
        document.getElementById('DropDownListTradeTermNew').value=arrayValue[4];
        
    }else 
    {
        document.getElementById('DropDownListTradeTermNew').options[0].selected=true;
        
    }if(arrayValue[5].length>0)
    {
        document.getElementById('DropDownListShipWayNew').value=arrayValue[5];
        
    }else 
    {
        document.getElementById('DropDownListShipWayNew').options[0].selected=true;
        
    }
}else 
{
    document.getElementById('HiddenVendorIDNew').value='';
    document.getElementById('QTextBoxVendorNameNew').value='';
    document.getElementById('QTextBoxVendorSiteNew').value='';
    document.getElementById('DropDownListCurrencyNew').options[0].selected=true;
    document.getElementById('DropDownListTradeTermNew').options[0].selected=true;
    document.getElementById('DropDownListShipWayNew').options[0].selected=true;
    
}"

我们来看看点击QLookUp的Search img后，弹出来的QLookUPSearchPage.aspx页面的URL是什么：

http://localhost/Pricing/Web/Public/QLookUPSearchPage.aspx?SQL=+WOeqS2Mk/H6E9ICwIOpVbfgAjIPH2onkkRF7fO6kaqZMiq7gRww2LfgAjIPH2onb0G0aFlDKnaVkj5ZYTna9yDKAZJIz8t1GzKRU95Ah7BZ9czLL/8qv94OjoxTQh3qpAIlrIFYcgI/yWSRJXF+z0WkMLZGBidybjtuO86fXa/6zGD5BBrbqWLysS4RIoiQ/Oq2RKy/Ajodoh7HD8ZKV1oFf7uPqCGstAVtzlVyUgjRZefLedBftM8UdZ8W+v33hsuJ6UTHjFEt8ANGdu0TZwypvrgOaoLbUqMWW37vSb1h4RbPScczZKhU88sr+56rVETs2B/XEur5ykVwvKf+1Q==&DataSource=9lDQbyO73rk=&ReturnClientID=QLookUpVendorNew&DataSourceType=EPS&WindowTitle=Select Vendor&CustomerFunction=if(clear!=1){objTextBoxText.value=arrayValue[1];document.getElementById('HiddenVendorIDNew').value=arrayValue[0];document.getElementById('QTextBoxVendorNameNew').value=arrayValue[2];document.getElementById('QTextBoxVendorSiteNew').value=arrayValue[3];if(arrayValue[6].length > 0){var DropDownListCurrencyNew = document.getElementById('DropDownListCurrencyNew'); for(i=0;i<DropDownListCurrencyNew.options.length;i!!!lionel!!!!!!lionel!!!){if(DropDownListCurrencyNew.options[i].text==arrayValue[6]){DropDownListCurrencyNew.options[i].selected = true;}}}  if(arrayValue[4].length > 0){document.getElementById('DropDownListTradeTermNew').value=arrayValue[4];} else{document.getElementById('DropDownListTradeTermNew').options[0].selected=true;}  if(arrayValue[5].length > 0){document.getElementById('DropDownListShipWayNew').value=arrayValue[5];} else{document.getElementById('DropDownListShipWayNew').options[0].selected=true;} } else {document.getElementById('HiddenVendorIDNew').value='';document.getElementById('QTextBoxVendorNameNew').value='';document.getElementById('QTextBoxVendorSiteNew').value='';document.getElementById('DropDownListCurrencyNew').options[0].selected=true;document.getElementById('DropDownListTradeTermNew').options[0].selected=true;document.getElementById('DropDownListShipWayNew').options[0].selected=true;}

数了一下：1857个字符。OK，截止目前，一切正常。

但是，新的需求来了，页面上要加Tax, 值也是从QLookUp中和Vendor Code一起选出来。
不用多想，肯定是往SQL和CustomerFunction两个属性里继续加。
但是加上以后就发现QLookUp摆工了，选不过来数据了。反复的Check也没发现SQL和CustomerFunction有什么语法错误。给CustomerFunction中加了一个alert(''), 竟然放到任何地方都不弹出Message。奇怪...？
把新加的所有内容全部去掉，还原到上面那样就没问题。
最后把Lionel同学拉过过一起研究，他说了一句“难道是URL太长了？”。
嗯？URL长度还有限制？先测试一下再说。把所有新加的内容一点点去掉，到某一点时，发现玄机：
给CustomerFunction中加一个alert('B'),      有问题;
把alert('B')改成var a;                                  没问题了
再把var a改成var a; var b;                          有问题

很明显，确实是CustomerFunction的长度导致了URL过长，从而引发了这个问题。

最后来Check一下有问题的URL：

http://localhost/Pricing/Web/Public/QLookUPSearchPage.aspx?SQL=+WOeqS2Mk/H6E9ICwIOpVbfgAjIPH2onkkRF7fO6kaqZMiq7gRww2LfgAjIPH2onb0G0aFlDKnaVkj5ZYTna9yDKAZJIz8t1GzKRU95Ah7BZ9czLL/8qv94OjoxTQh3qpeffefefeAIlrIFYcgI/yWSRJXF+z0WkMLZGBidybjtuO86fXa/6zGD5BBrbqWLysS4RIoiQ/Oq2RKy/Ajodoh7HD8ZKV1oFDFDGEdfwHBDFDFewf7uPqCGstAVtzlVyUgjRZefLedBftM8UdZ8W+v33hsuJ6UTHjFEt8ANGdu0TZwypvrgOaoLbUqMWW37vSb1h4RbPScczZKhU88sr+56rVETs2Bwrwr2324545322dfdf34t5Ggsde56rerFfdfytDFDFF85684hhhfhfghfjfn/XEur5ykVwvKf+1Q==&DataSource=9lDQbyO73rk=&ReturnClientID=QLookUpVendorNew&DataSourceType=EPS&WindowTitle=Select Vendor&CustomerFunction=if(clear!=1){ objTextBoxText.value=arrayValue[1]+' '+arrayValue[2];document.getElementById('HiddenVendorIDNew').value=arrayValue[0];document.getElementById('QTextBoxVendorNameNew').value=arrayValue[2];document.getElementById('QTextBoxVendorSiteNew').value=arrayValue[3]; document.getElementById('QTextBoxVendorTaxNew').value=arrayValue[7];if(arrayValue[6].length > 0){var DropDownListCurrencyNew = document.getElementById('DropDownListCurrencyNew'); for(i=0;i<DropDownListCurrencyNew.options.length;i!!!lionel!!!!!!lionel!!!){if(DropDownListCurrencyNew.options[i].text==arrayValue[6]){DropDownListCurrencyNew.options[i].selected = true;}}}  if(arrayValue[4].length > 0){document.getElementById('DropDownListTradeTermNew').value=arrayValue[4];} else{document.getElementById('DropDownListTradeTermNew').options[0].selected=true;}  if(arrayValue[5].length > 0){document.getElementById('DropDownListShipWayNew').value=arrayValue[5];} else{document.getElementById('DropDownListShipWayNew').options[0].selected=true;} } else {document.getElementById('HiddenVendorIDNew').value='';document.getElementById('QTextBoxVendorNameNew').value=''; document.getElementById('QTextBoxVendorTaxNew').value=’’;document.getElementById('QTextBoxVendorSiteNew').value='';document.getElementById('DropDownListCurrencyNew').options[0].selected=true;document.getElementById('DropDownListTradeTermNew').options[0].selected=true;document.getElementById('DropDownListShipWayNew').options[0].selected=true;}

数了一下：2087个字符。

我们来了解一下微软的说法：
http://support.microsoft.com/default.aspx?scid=kb;EN-US;q208427

Maximum URL length is 2,083 characters in Internet Explorer
Microsoft Internet Explorer has a maximum uniform resource locator (URL) length of 2,083 characters. Internet Explorer also has a maximum path length of 2,048 characters. This limit applies to both POST request and GET request URLs. 

If you are using the GET method, you are limited to a maximum of 2,048 characters, minus the number of characters in the actual path.

However, the POST method is not limited by the size of the URL for submitting name/value pairs. These pairs are transferred in the header and not in the URL. 

RFC 2616, "Hypertext Transfer Protocol -- HTTP/1.1," does not specify any requirement for URL length. 

已经明了. 我们最后的做法：

用一个JS function来给CustomerFunction瘦身，如下：

 <uc1:QLookUp ID="QLookUpVendorNew" runat="server" SelectOnly = "true"
                            CustomerFunction="if(clear!=1){objTextBoxText.value=arrayValue[1]+' '+arrayValue[2];SelectNewVendor(arrayValue);}else {document.getElementById('HiddenVendorIDNew').value='';document.getElementById('QTextBoxVendorTaxNew').value='';document.getElementById('QTextBoxVendorCurrencyNew').value='';document.getElementById('QTextBoxVendorSiteNew').value='';document.getElementById('DropDownListCurrencyNew').options[0].selected=true;document.getElementById('DropDownListTradeTermNew').options[0].selected=true;document.getElementById('DropDownListShipWayNew').options[0].selected=true;}"
                            alt="required::MSG500014::QButtonAdd" TextBoxCss="QTextBox" Width="160px" WindowTitle="Select Vendor" />

 

<script type="text/javascript">
        function SelectNewVendor(arrayValue)
        {
            document.getElementById('HiddenVendorIDNew').value=arrayValue[0];
            document.getElementById('QTextBoxVendorSiteNew').value=arrayValue[3];
            document.getElementById('QTextBoxVendorTaxNew').value=arrayValue[7];
            document.getElementById('QTextBoxVendorCurrencyNew').value=arrayValue[6];
            var dropCurrency=document.getElementById('DropDownListCurrencyNew');
            var dropTradeTerm=document.getElementById('DropDownListTradeTermNew');
            var dropShipway=document.getElementById('DropDownListShipWayNew');
             var neverSelect = true;
            //Currency DropDownList 
            if(arrayValue[6].length>0)
            {    
                neverSelect = true;           
                for(i=0;i<dropCurrency.options.length;i++)
                {
                    if(dropCurrency.options[i].text==arrayValue[6])
                    {
                        dropCurrency.options[i].selected=true;   
                        neverSelect = false;                        
                    }
                }               
                if(neverSelect == true) 
                {
                    dropCurrency.options[0].selected=true;       
                }   
            }
            else 
            {
                dropCurrency.options[0].selected=true;                
            }
            //Trade Term DropDownList
            if(trim(arrayValue[4]).length>0)
            {
                neverSelect = true;         
                for(i=0;i<dropTradeTerm.options.length;i++)
                {
                    if(dropTradeTerm.options[i].text==arrayValue[4])
                    {
                        dropTradeTerm.options[i].selected=true;   
                        neverSelect = false;                     
                    }
                }
                if(neverSelect == true) 
                {
                    dropTradeTerm.options[0].selected=true;       
                }    
            }
            else 
            {
                dropTradeTerm.options[0].selected=true;                
            }
            //Ship Way DropDownList
            if(arrayValue[5].length>0)
            {
                neverSelect = true;         
                for(i=0;i<dropShipway.options.length;i++)
                {
                    if(dropShipway.options[i].text==arrayValue[5])
                    {
                        dropShipway.options[i].selected=true;   
                        neverSelect = false;                     
                    }
                }
                if(neverSelect == true) 
                {
                    dropShipway.options[0].selected=true;       
                }
            }
            else
            {
                dropShipway.options[0].selected=true;                
            }
        }
        </script>

最后的URL：

http://hi4-ibmsv503/Pricing/Public/QLookUPSearchPage.aspx?SQL=+WOeqS2Mk/H6E9ICwIOpVbfgAjIPH2onkkRF7fO6kaqZMiq7gRww2LfgAjIPH2onb0G0aFlDKnaVkj5ZYTna9yDKAZJIz8t1GzKRU95Ah7BZ9czLL/8qv94OjoxTQh3qpAIlrIFYcgI/yWSRJXF+z0WkMLZGBidybjtuO86fXa/6zGD5BBrbqWLysS4RIoiQ/Oq2RKy/Ajodoh7HD8ZKV1oFf7uPqCGsYmBs6Ube9i5JGkg0e8sb/nN7x9b9SP8PqbyXWTXVbt98DyOiAYKN7awxVOfHJWy0OvMz9rA7KFv0p59zuOD8FNbB0jGbe/2Pu3D1GXeh6WxVE+6UVgrd8TRHpTYtNEN3KQhuZPWNhUI=&DataSource=9lDQbyO73rk=&ReturnClientID=QLookUpVendorNew&DataSourceType=EPS&WindowTitle=Select Vendor&CustomerFunction=if(clear!=1){objTextBoxText.value=arrayValue[1]!!!lionel!!!' '!!!lionel!!!arrayValue[2];SelectNewVendor(arrayValue);}else {document.getElementById('HiddenVendorIDNew').value='';document.getElementById('QTextBoxVendorTaxNew').value='';document.getElementById('QTextBoxVendorCurrencyNew').value='';document.getElementById('QTextBoxVendorSiteNew').value='';document.getElementById('DropDownListCurrencyNew').options[0].selected=true;document.getElementById('DropDownListTradeTermNew').options[0].selected=true;document.getElementById('DropDownListShipWayNew').options[0].selected=true;}

长度：1128个字符，OK了。