导出excel

<span style="font-size:18px;">/**
 * @param sql  查询语句
 * @param contentTitle excel表格标题名称
 * @param filepath   生成excel表格文件的路径
 * @param filename  excel表格的名称
 * @return 生成excel表格文件的路径
 */
public String ToExcel(String sql,String contentTitle,String filepath,String filename) {
        WritableWorkbook workbook = null;
        try{

            /**
             * 执行sql语句，查询数据库结果
             */
            List<Map> list = null;
            //获取结果中的字段
            if(list!=null && list.isEmpty()){
                //获取导出excel表格中所有的列字段名称
                Map<String,String> columnMap = list.get(0);
                Set<String> keySet = columnMap.keySet();

                /*
                 * 1，创建excel文件
                 */
                File file = new File(filepath);
                if (!file.exists()) {
                    file.mkdirs();
                }
                //获取文件的完整路径
                filename =file+"/"+filename+ ".xls";
                //创建excel文件
                File excelfile = new File(filename);
                excelfile.createNewFile();
                workbook = Workbook.createWorkbook(new FileOutputStream(excelfile));

                /*
                 * 2，写入excel文件标题和工作簿名称
                 */

                WritableSheet sheet = workbook.createSheet("sheet名称", 0);
                Label nL = null;
                jxl.write.WritableFont headerFont = new jxl.write.WritableFont(WritableFont.ARIAL, 18, WritableFont.BOLD, false, UnderlineStyle.NO_UNDERLINE, jxl.format.Colour.BLACK);
                jxl.write.WritableCellFormat headerFormat = new jxl.write.WritableCellFormat(headerFont);
                jxl.write.WritableFont titleFont = new jxl.write.WritableFont(WritableFont.ARIAL, 11, WritableFont.BOLD, false, UnderlineStyle.NO_UNDERLINE, jxl.format.Colour.BLACK);
                jxl.write.WritableCellFormat titleFormat = new jxl.write.WritableCellFormat(titleFont);

                /*
                 * 3，写入标题
                 */
                nL = new Label(0, 0, contentTitle, headerFormat);
                sheet.addCell(nL);
                /*
                 * 4，写入内容
                 */
                Label label;
                int index = 0;
                for(String key:keySet){
                    nL = new Label(index, 1, key, titleFormat);
                    sheet.addCell(nL);
                    for (int j = 0; j < list.size(); j++) {
                        //得到单元格的列所对应的值
                        String value = (String) list.get(j).get(key);
                        //把值放入单元格中
                        Label obj = new Label(index, j + 2, value);
                        sheet.addCell(obj);
                    }
                    index++;
                }
                workbook.write();
                workbook.close();
            }
        }catch(Exception e){
            e.printStackTrace();
        }
        return filename;
    }</span>