首先引入两份JS:copyhtmltoexcel.js以及 tableToExcel.js
复制代码 代码如下:
/*
 * 默认转换实现函数，如果需要其他功能，需自行扩展
 * 参数：
 *      tableID : HTML中Table对象id属性值
 * 详细用法参见以下 TableToExcel 对象定义 
 */
function saveAsExcel(tableID){
 var tb = new TableToExcel(tableID);
  tb.setFontStyle("Courier New");
  tb.setFontSize(10);
  tb.setTableBorder(2);
  tb.setColumnWidth(7);
  tb.isLineWrap(false);
  tb.isAutoFit(true);
  tb.getExcelFile();
}

/*
 *  功能：HTML中Table对象转换为Excel通用对象.
 *  作者：Jeva
 *  时间：2006-08-09
 *  参数：tableID  HTML中Table对象的ID属性值
 *  说明：
 *       能适应复杂的HTML中Table对象的自动转换，能够自动根据行列扩展信息
 *       合并Excel中的单元格，客户端需要安装有Excel
 *       详细的属性、方法引用说明参见：Excel的Microsoft Excel Visual Basic参考
 *  示范：
 *       var tb = new TableToExcel('demoTable');
 *    tb.setFontStyle("Courier New");
 *    tb.setFontSize(10);  //推荐取值10
 *    tb.setFontColor(6);  //一般情况不用设置
 *    tb.setBackGround(4);  //一般情况不用设置
 *    tb.setTableBorder(2);  //推荐取值2
 *    tb.setColumnWidth(10);  //推荐取值10
 *    tb.isLineWrap(false);
 *    tb.isAutoFit(true);
 *   
 *    tb.getExcelFile();
 *   如果设置了单元格自适应，则设置单元格宽度无效
 *  版本：1.0
 */
function TableToExcel(tableID) {
    this.tableBorder = -1; //边框类型，-1没有边框 可取1/2/3/4
    this.backGround = 0; //背景颜色：白色   可取调色板中的颜色编号 1/2/3/4....
    this.fontColor = 1;  //字体颜色：黑色
    this.fontSize = 10;  //字体大小
    this.fontStyle = "宋体"; //字体类型
    this.rowHeight = -1; //行高
    this.columnWidth = -1; //列宽
    this.lineWrap = true; //是否自动换行
    this.textAlign = -4108; //内容对齐方式   默认为居中
    this.autoFit = false;  //是否自适应宽度
    this.tableID = tableID;
}

TableToExcel.prototype.setTableBorder = function (excelBorder) {
    this.tableBorder = excelBorder ;
};

TableToExcel.prototype.setBackGround = function (excelColor) {
    this.backGround = excelColor;
};

TableToExcel.prototype.setFontColor = function (excelColor) {
    this.fontColor = excelColor;
};

TableToExcel.prototype.setFontSize = function (excelFontSize) {
    this.fontSize = excelFontSize;
};

TableToExcel.prototype.setFontStyle = function (excelFont) {
    this.fontStyle = excelFont;
};

TableToExcel.prototype.setRowHeight = function (excelRowHeight) {
    this.rowHeight = excelRowHeight;
};

TableToExcel.prototype.setColumnWidth = function (excelColumnWidth) {
    this.columnWidth = excelColumnWidth;
};

TableToExcel.prototype.isLineWrap = function (lineWrap) {
    if (lineWrap == false || lineWrap == true) {
        this.lineWrap = lineWrap;
    }
};

TableToExcel.prototype.setTextAlign = function (textAlign) {
    this.textAlign = textAlign;
};

TableToExcel.prototype.isAutoFit = function(autoFit){
 if(autoFit == true || autoFit == false)
  this.autoFit = autoFit ;
}

//文件转换主函数
TableToExcel.prototype.getExcelFile = function () {
    var jXls, myWorkbook, myWorksheet, myHTMLTableCell, myExcelCell, myExcelCell2;
    var myCellColSpan, myCellRowSpan;

    try {
        jXls = new ActiveXObject('Excel.Application');
    }
    catch (e) {
        alert("无法启动Excel!\n\n" + e.message +
           "\n\n如果您确信您的电脑中已经安装了Excel，"+
           "那么请调整IE的安全级别。\n\n具体操作：\n\n"+
           "工具 → Internet选项 → 安全 → 自定义级别 → ActiveX控件和插件 \n\n" +
       "→ 启用 : 对没有标记为安全的ActiveX控件进行初始化和脚本运行");
        return false;
    }

    jXls.Visible = true;
    myWorkbook = jXls.Workbooks.Add();
    jXls.DisplayAlerts = false;
    myWorkbook.Worksheets(3).Delete();
    myWorkbook.Worksheets(2).Delete();
    jXls.DisplayAlerts = true;
    myWorksheet = myWorkbook.ActiveSheet;

    var  readRow = 0,  readCol = 0;
    var totalRow = 0, totalCol = 0;
    var   tabNum = 0;

//设置行高、列宽
    if(this.columnWidth != -1)
     myWorksheet.Columns.ColumnWidth = this.columnWidth;
    else
     myWorksheet.Columns.ColumnWidth = 7;
    if(this.rowHeight != -1)
     myWorksheet.Rows.RowHeight = this.rowHeight ;

//搜索需要转换的Table对象，获取对应行、列数
    var obj = document.all.tags("table");
    for (x = 0; x < obj.length; x++) {
        if (obj[x].id == this.tableID) {
            tabNum = x;
            totalRow = obj[x].rows.length;
            for (i = 0; i < obj[x].rows[0].cells.length; i++) {
                myHTMLTableCell = obj[x].rows(0).cells(i);
                myCellColSpan = myHTMLTableCell.colSpan;
                totalCol = totalCol + myCellColSpan;
            }
        }
    }

//开始构件模拟表格
    var excelTable = new Array();
    for (i = 0; i <= totalRow; i++) {
        excelTable[i] = new Array();
        for (t = 0; t <= totalCol; t++) {
            excelTable[i][t] = false;
        }
    }

//开始转换表格   
    for (z = 0; z < obj[tabNum].rows.length; z++) {
        readRow = z + 1;
        readCol = 1;
        for (c = 0; c < obj[tabNum].rows(z).cells.length; c++) {
            myHTMLTableCell = obj[tabNum].rows(z).cells(c);
            myCellColSpan = myHTMLTableCell.colSpan;
            myCellRowSpan = myHTMLTableCell.rowSpan;
            for (y = 1; y <= totalCol; y++) {
                if (excelTable[readRow][y] == false) {
                    readCol = y;
                    break;
                }
            }
            if (myCellColSpan * myCellRowSpan > 1) {
                myExcelCell = myWorksheet.Cells(readRow, readCol);
                myExcelCell2 = myWorksheet.Cells(readRow + myCellRowSpan - 1, readCol + myCellColSpan - 1);
                myWorksheet.Range(myExcelCell, myExcelCell2).Merge();
                myExcelCell.HorizontalAlignment = this.textAlign;
                myExcelCell.Font.Size = this.fontSize;
                myExcelCell.Font.Name = this.fontStyle;
                myExcelCell.wrapText = this.lineWrap;
                myExcelCell.Interior.ColorIndex = this.backGround;
                myExcelCell.Font.ColorIndex = this.fontColor;
                if(this.tableBorder != -1){
                 myWorksheet.Range(myExcelCell, myExcelCell2).Borders(1).Weight = this.tableBorder ;
                 myWorksheet.Range(myExcelCell, myExcelCell2).Borders(2).Weight = this.tableBorder ;
                 myWorksheet.Range(myExcelCell, myExcelCell2).Borders(3).Weight = this.tableBorder ;
                 myWorksheet.Range(myExcelCell, myExcelCell2).Borders(4).Weight = this.tableBorder ;
                }

                myExcelCell.Value = myHTMLTableCell.innerText;
                for (row = readRow; row <= myCellRowSpan + readRow - 1; row++) {
                    for (col = readCol; col <= myCellColSpan + readCol - 1; col++) {
                        excelTable[row][col] = true;
                    }
                }

                readCol = readCol + myCellColSpan;
            } else {
                myExcelCell = myWorksheet.Cells(readRow, readCol);
                myExcelCell.Value = myHTMLTableCell.innerText;
                myExcelCell.HorizontalAlignment = this.textAlign;
                myExcelCell.Font.Size = this.fontSize;
                myExcelCell.Font.Name = this.fontStyle;
                myExcelCell.wrapText = this.lineWrap;
                myExcelCell.Interior.ColorIndex = this.backGround;
                myExcelCell.Font.ColorIndex = this.fontColor;
                if(this.tableBorder != -1){
                 myExcelCell.Borders(1).Weight = this.tableBorder ;
                 myExcelCell.Borders(2).Weight = this.tableBorder ;
                 myExcelCell.Borders(3).Weight = this.tableBorder ;
                 myExcelCell.Borders(4).Weight = this.tableBorder ;
                }              
                excelTable[readRow][readCol] = true;
                readCol = readCol + 1;
            }
        }
    }
    if(this.autoFit == true)
     myWorksheet.Columns.AutoFit;

    jXls.UserControl = true;
    jXls = null;
    myWorkbook = null;
    myWorksheet = null;
};

copyhtmltoexcel.js

复制代码 代码如下:
//elTalbeOut 这个为导出内容的外层表格，主要是设置border之类的样式，elDiv则是整个导出的html部分
function onhtmlToExcel(elTableOut,elDiv){
 try{
  //设置导出前的数据，为导出后返回格式而设置
  var elDivStrBak = elDiv.innerHTML;
  //设置table的border=1，这样到excel中就有表格线 ps:感谢双面提醒
  elTableOut.border=1;
  //过滤elDiv内容
  var elDivStr = elDiv.innerHTML;
  elDivStr = replaceHtml(elDivStr,"<A",">");
  elDivStr = replaceHtml(elDivStr,"</A",">");
  elDiv.innerHTML=elDivStr; 

  var oRangeRef = document.body.createTextRange();
  oRangeRef.moveToElementText( elDiv );
  oRangeRef.execCommand("Copy");

  //返回格式变换以前的内容
  elDiv.innerHTML = elDivStrBak;
  //内容数据可能很大，所以赋空
  elDivStrBak = "";
  elDivStr = "";

  var oXL = new ActiveXObject("Excel.Application")
  var oWB = oXL.Workbooks.Add ;
  var oSheet = oWB.ActiveSheet ;
  oSheet.Paste();
  oSheet.Cells.NumberFormatLocal = "@";
  oSheet.Columns("D:D").Select
  oXL.Selection.ColumnWidth = 20
  oXL.Visible = true;  
  oSheet = null;
  oWB = null;
  appExcel = null;
 }catch(e){
  alert(e.description)
 }
}

function replaceHtml(replacedStr,repStr,endStr){  
  var replacedStrF = "";  
  var replacedStrB = "";  
  var repStrIndex = replacedStr.indexOf(repStr);  
  while(repStrIndex != -1){  
      replacedStrF = replacedStr.substring(0,repStrIndex);  
      replacedStrB = replacedStr.substring(repStrIndex,replacedStr.length);  
      replacedStrB = replacedStrB.substring(replacedStrB.indexOf(endStr)+1,replacedStrB.length);  
      replacedStr = replacedStrF + replacedStrB;  
      repStrIndex = replacedStr.indexOf(repStr);  
  }  
  return replacedStr;
}

在JSP页面中写JS方法
复制代码 代码如下:
  //生成Excel
  function onTableToExcel(){
   var elTableOut = document.getElementById("elTableOut");
   var elDiv = document.getElementById("elDiv");
   onhtmlToExcel(elTableOut,elDiv);
  }

注意事项：使用JS导出excel需要设置IE的active。注意最佳的是IE8浏览器。至于在java后台实现excel还没去研究，希望各位大神指教。