ApachePOI 動態列表生成excel

先創建導出Excel的工具類，并帶泛型，實體一定要生成屬性的get方法，就是普通的Javabean，后面的就是個人發揮了，廢話不多說，直接上代碼：

public class ExportExcel<T> {


public void exportExcel(Collection<T> dataset, OutputStream out) {
      exportExcel("數據導出", null, dataset, out, "yyyy-MM-dd hh:MM:ss");
   }

   public void exportExcel(String[] headers, Collection<T> dataset,
         OutputStream out) {
      exportExcel("數據導出", headers, dataset, out, "yyyy-MM-dd hh:MM:ss");
   }

   public void exportExcel(String[] headers, Collection<T> dataset,
         OutputStream out, String pattern) {
      exportExcel("數據導出", headers, dataset, out, pattern);
   }

   public void exportExcel(String title, String[] headers,
             Collection<T> dataset, OutputStream out, String pattern) {
          // 聲明一個工作薄
          HSSFWorkbook workbook = new HSSFWorkbook();
          // 生成一個表格
          HSSFSheet sheet = workbook.createSheet(title);
          // 設置表格默認列寬度為30個字節
          sheet.setDefaultColumnWidth(30);
          // 生成一個樣式
          HSSFCellStyle style = workbook.createCellStyle();
          // 設置這些樣式
          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);
          // 標題字體
          HSSFFont font = workbook.createFont();
          font.setColor(HSSFColor.BLACK.index);
          font.setFontHeightInPoints((short) 12);
          font.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
          // 把字體應用到當前的樣式
          style.setFont(font);
          // 生成并設置另一個樣式
          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);
          // 內容字體
          HSSFFont font2 = workbook.createFont();
          font2.setColor(HSSFColor.BLACK.index);
          font2.setBoldweight(HSSFFont.BOLDWEIGHT_NORMAL);
          // 把字體應用到當前的樣式
          style2.setFont(font2);

          // 聲明一個畫圖的頂級管理器
          HSSFPatriarch patriarch = sheet.createDrawingPatriarch();
          // 定義注釋的大小和位置,詳見文檔
          HSSFComment comment = patriarch.createComment(new HSSFClientAnchor(0, 0, 0, 0, (short) 4, 2, (short) 6, 5));
          // 設置注釋內容
          comment.setString(new HSSFRichTextString("注釋！"));
          // 設置注釋作者，當鼠標移動到單元格上是可以在狀態欄中看到該內容.
          comment.setAuthor("yuyidi");

          //產生表格標題行
          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);
          }

          //遍歷集合數據，產生數據行
          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，根據javabean屬性的先后順序，動態調用getXxx()方法得到屬性值
             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[] {});
                    //判斷值的類型后進行強制類型轉換
                    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[]) {
                       // 有圖片時，設置行高為60px;
                       row.setHeightInPoints(60);
                       // 設置圖片所在列寬度為80px,注意這里單位的一個換算
                       sheet.setColumnWidth(i, (short) (35.7 * 80));
                       // sheet.autoSizeColumn(i);
                       byte[] bsValue = (byte[]) value;
                       HSSFClientAnchor anchor = new HSSFClientAnchor(0, 0,
                             1023, 255, (short) 6, index, (short) 6, index);
                       anchor.setAnchorType(2);
                       patriarch.createPicture(anchor, workbook.addPicture(
                             bsValue, HSSFWorkbook.PICTURE_TYPE_JPEG));
                    } else{
                       //其它數據類型都當作字符串簡單處理
                       textValue = objToString(value);
                    }
                    //如果不是圖片數據，就利用正則表達式判斷textValue是否全部由數字組成
                    if(textValue!=null){
                       Pattern p = Pattern.compile("^//d+(//.//d+)?$");  
                       Matcher matcher = p.matcher(textValue);
                       if(matcher.matches()){
                          //是數字當作double處理
                          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 {
                    //清理資源
                }
             }

          }
          try {
             workbook.write(out);
          } catch (IOException e) {
             e.printStackTrace();
          }
   }

   private String objToString(Object obj){
        return (obj == null) ? "" : obj.toString();
   }

}</pre>