最近工作中用到的POI匯入匯出Excel檔案的地方比較到，所以就乘機總結一下，在這裡先說以匯出Excel的情況簡單的說一下，現在就直接上程式碼，在程式碼上面做註釋了。

    /**
     * 處理匯出的資料資訊
     * @param list
     * @return
     */
    private int rownum = 0;   //在這裡是建立一個全域性變數，用來表示建立的行數
    private void exportExcelData(String title,List<String> headerList,List<Yangbyj> dataList,HttpServletResponse response, String fileName) throws
 
 Exception{
        //建立excel檔案
        SXSSFWorkbook sxssfWorkbook = new SXSSFWorkbook(500);
        //建立sheet頁面
        Sheet createSheet  = sxssfWorkbook.createSheet("Export");
        //建立excel的檔案樣式
        Map<String, CellStyle> createStyles = createStyles(sxssfWorkbook);
        //建立標題
        if(StringUtils.isNotBlank(title)){
            //建立sheet中的行
 

            Row titleRow = createSheet.createRow(rownum++);
            titleRow.setHeightInPoints(30);  //設定行高
            Cell titleCell = titleRow.createCell(0);  //建立標題的單元格
            titleCell.setCellStyle(createStyles.get("title"));   //設定單元格的樣式
            titleCell.setCellValue(title);  //給單元格賦值
            //合併單元格
 

            createSheet.addMergedRegion(new CellRangeAddress(titleRow.getRowNum(),
                    titleRow.getRowNum(),titleRow.getRowNum(),headerList.size()-1));
        }
        //建立表頭
        if(headerList == null||headerList.size()==0){
            throw new RuntimeException("headerList not null!");
        }
        //建立表頭行
        Row headerRow = createSheet.createRow(rownum++);
        headerRow.setHeightInPoints(16);
        for(int i=0;i<headerList.size();i++){
            Cell cell = headerRow.createCell(i);
            cell.setCellStyle(createStyles.get("header"));
            cell.setCellValue(headerList.get(i));
            /*給表格新增批註
             * Comment comment = createSheet.createDrawingPatriarch().createCellComment(
                    new XSSFClientAnchor(0, 0, 0, 0, 3, 3, 5, 6));
            cell.setCellComment(comment);*/
            createSheet.autoSizeColumn(i);  //自動調整列寬
        }
        //設定寬度
        for(int i=0;i<headerList.size();i++){
            int colWidth = createSheet.getColumnWidth(i)*2;
            createSheet.setColumnWidth(i, colWidth < 3000 ? 3000 : colWidth);
        }
        //處理資料資訊
        for (Yangbyj y : dataList) {
                Row row = createSheet.createRow(rownum++);
                CellStyle style = createStyles.get("data2");
                Cell oneCell = row.createCell(0);
                DataFormat format = sxssfWorkbook.createDataFormat();
                style.setDataFormat(format.getFormat("yyyy/MM/dd"));
                oneCell.setCellValue((Date) y.getShij());
                oneCell.setCellStyle(style);
                Cell twoCell = row.createCell(1);
                twoCell.setCellValue( y.getYunj());
                twoCell.setCellStyle(style);
        }
        //通過瀏覽器將資料寫出來
        response.reset();
        response.setContentType("application/octet-stream; charset=utf-8");
        response.setHeader("Content-Disposition", "attachment; filename="+Encodes.urlEncode(fileName));
        sxssfWorkbook.write(response.getOutputStream());
    }

下面是excel的樣式，可以直接拿來用。

private Map<String, CellStyle> createStyles(Workbook wb) {
        Map<String, CellStyle> styles = new HashMap<String, CellStyle>();

        CellStyle style = wb.createCellStyle();
        style.setAlignment(CellStyle.ALIGN_CENTER);
        style.setVerticalAlignment(CellStyle.VERTICAL_CENTER);
        Font titleFont = wb.createFont();
        titleFont.setFontName("Arial");
        titleFont.setFontHeightInPoints((short) 16);
        titleFont.setBoldweight(Font.BOLDWEIGHT_BOLD);
        style.setFont(titleFont);
        styles.put("title", style);

        style = wb.createCellStyle();
        style.setVerticalAlignment(CellStyle.VERTICAL_CENTER);
        style.setBorderRight(CellStyle.BORDER_THIN);
        style.setRightBorderColor(IndexedColors.GREY_50_PERCENT.getIndex());
        style.setBorderLeft(CellStyle.BORDER_THIN);
        style.setLeftBorderColor(IndexedColors.GREY_50_PERCENT.getIndex());
        style.setBorderTop(CellStyle.BORDER_THIN);
        style.setTopBorderColor(IndexedColors.GREY_50_PERCENT.getIndex());
        style.setBorderBottom(CellStyle.BORDER_THIN);
        style.setBottomBorderColor(IndexedColors.GREY_50_PERCENT.getIndex());
        Font dataFont = wb.createFont();
        dataFont.setFontName("Arial");
        dataFont.setFontHeightInPoints((short) 10);
        style.setFont(dataFont);
        styles.put("data", style);

        style = wb.createCellStyle();
        style.cloneStyleFrom(styles.get("data"));
        style.setAlignment(CellStyle.ALIGN_LEFT);
        styles.put("data1", style);

        style = wb.createCellStyle();
        style.cloneStyleFrom(styles.get("data"));
        style.setAlignment(CellStyle.ALIGN_CENTER);
        styles.put("data2", style);

        style = wb.createCellStyle();
        style.cloneStyleFrom(styles.get("data"));
        style.setAlignment(CellStyle.ALIGN_RIGHT);
        styles.put("data3", style);

        style = wb.createCellStyle();
        style.cloneStyleFrom(styles.get("data"));
//      style.setWrapText(true);
        style.setAlignment(CellStyle.ALIGN_CENTER);
        style.setFillForegroundColor(IndexedColors.GREY_50_PERCENT.getIndex());
        style.setFillPattern(CellStyle.SOLID_FOREGROUND);
        Font headerFont = wb.createFont();
        headerFont.setFontName("Arial");
        headerFont.setFontHeightInPoints((short) 10);
        headerFont.setBoldweight(Font.BOLDWEIGHT_BOLD);
        headerFont.setColor(IndexedColors.WHITE.getIndex());
        style.setFont(headerFont);
        styles.put("header", style);

        return styles;
    }

上面只是簡單的說以下我這裡用到的部分，後續的自己也在學習中，多多斧正。