excel导出优化

    @SuppressWarnings("unused")
    public static <T> SXSSFWorkbook export1(HttpServletResponse response, String fileName, String[] excelHeader,
            List<T> dataList) throws Exception {
        
        response.setContentType("application/x-download");
        response.setCharacterEncoding("utf-8");// 处理编码问题
        response.setHeader("Content-Disposition",
                "attachment;filename=" + new String(fileName.getBytes("gbk"), "iso8859-1") + ".xls");// 表头编码问题
        XSSFWorkbook wb = new XSSFWorkbook();
        SXSSFWorkbook sxssfWorkbook = new SXSSFWorkbook(wb, 100);
        
        
        SXSSFSheet sheet = sxssfWorkbook.createSheet();
//        Sheet sheet = sxssfWorkbook.getSheetAt(0);
        
        // 标题数组
        String[] titleArray = new String[excelHeader.length];
        // 字段名数组
        String[] fieldArray = new String[excelHeader.length];
        for (int i = 0; i < excelHeader.length; i++) {
            String[] tempArray = excelHeader[i].split("#");
            titleArray[i] = tempArray[0];
            fieldArray[i] = tempArray[1];
        }
        
        // 在sheet中添加标题行
        sheet.trackAllColumnsForAutoSizing();
        Row row = sheet.createRow(0);// 行数从0开始
        // 自动设置宽度
        sheet.autoSizeColumn(0);
        // 设置表格默认列宽度
        sheet.setDefaultColumnWidth(20);
        
        // 为标题行赋值
        for (int i = 0; i < titleArray.length; i++) {
            // 需要序号就需要+1 因为0号位被序号占用
            Cell titleCell = row.createCell(i);
            titleCell.setCellValue(titleArray[i]);
            sheet.autoSizeColumn(i + 1); // 0 号被序号占用
            
        }
        
        Map<String, Method> map = new HashMap<String, Method>();
        for (int index = 1; index < dataList.size(); index++) {
            row = sheet.createRow(index);
            // 利用反射 根据传过来的字段名数组，动态调用对应的getxxx()方法得到属性值
            long start = System.currentTimeMillis();
            for (int i = 0; i < fieldArray.length; i++) {
                // 需要序号 就需要 i+1
                Cell dataCell = row.createCell(i);
                String fieldName = fieldArray[i];
                // 取得对应的getxxx()方法  实体类命名一定要用驼峰才能分割成功
                String getMethodName = "get" + fieldName.substring(0, 1).toUpperCase() + fieldName.substring(1);
                Method getMethod = map.get(getMethodName);
                if(getMethod == null){
//                    Class<? extends Object> tCls = t.getClass();// 泛型为Object以及所有Object的子类
                    getMethod = dataList.get(index).getClass().getMethod(getMethodName);// 通过方法名得到对应的方法
                    getMethod.setAccessible(true);
                    map.put(getMethodName, getMethod);
                }
                Object value = getMethod.invoke(dataList.get(index));// 动态调用方法,得到属性值
                if (value != null) {
                    dataCell.setCellValue(value.toString());// 为当前列赋值
                }
            }
            long end = System.currentTimeMillis();
            System.out.println("循环花费的时间:"+(end-start)+" milliseconds");
        }
        OutputStream outputStream = response.getOutputStream();// 打开流  
        sxssfWorkbook.write(outputStream);// HSSFWorkbook写入流  
        sxssfWorkbook.close();// HSSFWorkbook关闭  
        outputStream.flush();// 刷新流  
        outputStream.close();// 关闭流  
        
        return sxssfWorkbook;
        
    }