EasyUI----DataGrid 导出 Excel

最近做的安防项目有个功能，需要把DataGrid中的数据导出，下面通过代码一步一步的介绍;
首先在js中写一个扩展类，主要的功能是把DataGrid中的数据转换成Excel的XML格式

'''将datagrid中的数据转换成Excel的XML格式'''

$.extend($.fn.datagrid.methods, {
    getExcelXml: function (jq, param) {
   
        var worksheet = this.createWorksheet(jq, param);
        //alert($(jq).datagrid('getColumnFields'));
        var totalWidth = 0;
        var cfs = $(jq).datagrid('getColumnFields');
        for (var i = 0; i < cfs.length; i++) {
            totalWidth += $(jq).datagrid('getColumnOption', cfs[i]).width;
        }
        //var totalWidth = this.getColumnModel().getTotalWidth(includeHidden);
        return '<xml version="1.0" encoding="utf-8">' +
            '<ss:Workbook xmlns:ss="urn:schemas-microsoft-com:office:spreadsheet" xmlns:x="urn:schemas-microsoft-com:office:excel" xmlns:o="urn:schemas-microsoft-com:office:office">' +
            '<o:DocumentProperties><o:Title>' + param.title + '</o:Title></o:DocumentProperties>' +
            '<ss:ExcelWorkbook>' +
            '<ss:WindowHeight>' + worksheet.height + '</ss:WindowHeight>' +
            '<ss:WindowWidth>' + worksheet.width + '</ss:WindowWidth>' +
            '<ss:ProtectStructure>False</ss:ProtectStructure>' +
            '<ss:ProtectWindows>False</ss:ProtectWindows>' +
            '</ss:ExcelWorkbook>' +
            '<ss:Styles>' +
            '<ss:Style ss:ID="Default">' +
            '<ss:Alignment ss:Vertical="Top"  />' +
            '<ss:Font ss:FontName="arial" ss:Size="10" />' +
            '<ss:Borders>' +
            '<ss:Border  ss:Weight="1" ss:LineStyle="Continuous" ss:Position="Top" />' +
            '<ss:Border  ss:Weight="1" ss:LineStyle="Continuous" ss:Position="Bottom" />' +
            '<ss:Border  ss:Weight="1" ss:LineStyle="Continuous" ss:Position="Left" />' +
            '<ss:Border ss:Weight="1" ss:LineStyle="Continuous" ss:Position="Right" />' +