ApachePOI 动态列表生成excel

public class ExportExcel<T> {
     
    public void exportExcel(Collection<T> dataset,OutputStream out) {
          exportExcel("数据导出",null,dataset,out,"yyyy-MM-dd hh:MM:ss");
       }
      
       public void exportExcel(String[] headers,Collection<T> dataset,headers,OutputStream out,String pattern) {
          exportExcel("数据导出",pattern);
       }
        
       public void exportExcel(String title,String[] headers,String pattern) {
              // 声明一个工作薄
              HSSFWorkbook workbook = new HSSFWorkbook();
              // 生成一个表格
              HSSFSheet sheet = workbook.createSheet(title);
              // 设置表格默认列宽度为30个字节
              sheet.setDefaultColumnWidth(30);
              // 生成一个样式
              HSSFCellStyle style = workbook.createCellStyle();
              // 设置这些样式
              style.setFillForegroundColor(HSSFColor.WHITE.index);
              style.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);
              style.setBorderBottom(HSSFCellStyle.BORDER_THIN);
              style.setBorderLeft(HSSFCellStyle.BORDER_THIN);
              style.setBorderRight(HSSFCellStyle.BORDER_THIN);
              style.setBorderTop(HSSFCellStyle.BORDER_THIN);
              style.setAlignment(HSSFCellStyle.ALIGN_CENTER);
              // 标题字体
              HSSFFont font = workbook.createFont();
              font.setColor(HSSFColor.BLACK.index);
              font.setFontHeightInPoints((short) 12);
              font.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
              // 把字体应用到当前的样式
              style.setFont(font);
              // 生成并设置另一个样式
              HSSFCellStyle style2 = workbook.createCellStyle();
              style2.setFillForegroundColor(HSSFColor.WHITE.index);
              style2.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);
              style2.setBorderBottom(HSSFCellStyle.BORDER_THIN);
              style2.setBorderLeft(HSSFCellStyle.BORDER_THIN);
              style2.setBorderRight(HSSFCellStyle.BORDER_THIN);
              style2.setBorderTop(HSSFCellStyle.BORDER_THIN);
              style2.setAlignment(HSSFCellStyle.ALIGN_CENTER);
              style2.setVerticalAlignment(HSSFCellStyle.VERTICAL_CENTER);
              // 内容字体
              HSSFFont font2 = workbook.createFont();
              font2.setColor(HSSFColor.BLACK.index);
              font2.setBoldweight(HSSFFont.BOLDWEIGHT_NORMAL);
              // 把字体应用到当前的样式
              style2.setFont(font2);
              
              // 声明一个画图的顶级管理器
              HSSFPatriarch patriarch = sheet.createDrawingPatriarch();
              // 定义注释的大小和位置,详见文档
              HSSFComment comment = patriarch.createComment(new HSSFClientAnchor(0,(short) 4,2,(short) 6,5));
              // 设置注释内容
              comment.setString(new HSSFRichTextString("注释！"));
              // 设置注释作者，当鼠标移动到单元格上是可以在状态栏中看到该内容.
              comment.setAuthor("yuyidi");
          
              //产生表格标题行
              HSSFRow row = sheet.createRow(0);
              for (int i = 0; i < headers.length; i++) {
                 HSSFCell cell = row.createCell(i);
                 cell.setCellStyle(style);
                 HSSFRichTextString text = new HSSFRichTextString(headers[i]);
                 cell.setCellValue(text);
              }
          
              //遍历集合数据，产生数据行
              Iterator<T> it = dataset.iterator();
              int index = 0;
              while (it.hasNext()) {
                 index++;
                 row = sheet.createRow(index);
                 T t = (T) it.next();
                 //利用反射，根据javabean属性的先后顺序，动态调用getXxx()方法得到属性值
                 Field[] fields = t.getClass().getDeclaredFields();
                 for (int i = 0; i < fields.length; i++) {
                    HSSFCell cell = row.createCell(i);
                    cell.setCellStyle(style2);
                    Field field = fields[i];
                    String fieldName = field.getName();
                    String getMethodName = "get"
                           + fieldName.substring(0,1).toUpperCase()
                           + fieldName.substring(1);
                    try {
                        Class tCls = t.getClass();
                        Method getMethod = tCls.getMethod(getMethodName,new Class[] {});
                        Object value = getMethod.invoke(t,new Object[] {});
                        //判断值的类型后进行强制类型转换
                        String textValue = null;
                       if (value instanceof Date) {
                           Date date = (Date) value;
                           SimpleDateFormat sdf = new SimpleDateFormat(pattern);
                            textValue = sdf.format(date);
                       }else if (value instanceof Double) {
                            textValue = formatter.format(value);
                        }  else if (value instanceof byte[]) {
                           // 有图片时，设置行高为60px;
                           row.setHeightInPoints(60);
                           // 设置图片所在列宽度为80px,注意这里单位的一个换算
                           sheet.setColumnWidth(i,(short) (35.7 * 80));
                           // sheet.autoSizeColumn(i);
                           byte[] bsValue = (byte[]) value;
                           HSSFClientAnchor anchor = new HSSFClientAnchor(0,1023,255,index,index);
                           anchor.setAnchorType(2);
                           patriarch.createPicture(anchor,workbook.addPicture(
                                 bsValue,HSSFWorkbook.PICTURE_TYPE_JPEG));
                        } else{
                           //其它数据类型都当作字符串简单处理
                           textValue = objToString(value);
                        }
                        //如果不是图片数据，就利用正则表达式判断textValue是否全部由数字组成
                        if(textValue!=null){
                           Pattern p = Pattern.compile("^//d+(//.//d+)?$");  
                           Matcher matcher = p.matcher(textValue);
                           if(matcher.matches()){
                              //是数字当作double处理
                              cell.setCellValue(Double.parseDouble(textValue));
                           }else{
                              HSSFRichTextString richString = new HSSFRichTextString(textValue);
                              cell.setCellValue(richString);
                           }
                        }
                    } catch (SecurityException e) {
                        e.printStackTrace();
                    } catch (NoSuchMethodException e) {
                        e.printStackTrace();
                    } catch (IllegalArgumentException e) {
                        e.printStackTrace();
                    } catch (IllegalAccessException e) {
                        e.printStackTrace();
                    } catch (InvocationTargetException e) {
                        e.printStackTrace();
                    } finally {
                        //清理资源
                    }
                 }
          
              }
              try {
                 workbook.write(out);
              } catch (IOException e) {
                 e.printStackTrace();
              }
       }
        
       private String objToString(Object obj){
            return (obj == null) ? "" : obj.toString();
       }
}