poi技术导出海量数据到excel

http://poi.apache.org/download.html这是包的下载网站

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//导出数据到EXCEL表格

public static void ExportLgExcel(HttpServletRequest request, HttpServletResponse resp) throws Exception {



//读取指定目录下面的excel导出模板

String excelDir = request.getServletContext().getRealPath("/upload/ExcelStencil");

Workbook wb = null;

try {

wb = new XSSFWorkbook(new FileInputStream(new File(excelDir + "/lightList.xlsx")));

} catch (Exception e) {

wb = new HSSFWorkbook(new FileInputStream(new File(excelDir + "/lightList.xls")));

}

// 创建字体，设置其为红色、粗体：

Font font = wb.createFont();

font.setColor(Font.COLOR_RED);

font.setBoldweight(Font.BOLDWEIGHT_BOLD);

//创建格式

CellStyle cellStyle = wb.createCellStyle();

cellStyle.setFont(font);

cellStyle.setBorderBottom(CellStyle.BORDER_THIN);

cellStyle.setBorderRight(CellStyle.BORDER_THIN);

CellStyle cellStyleBorder = wb.createCellStyle();

cellStyleBorder.setBorderBottom(CellStyle.BORDER_THIN);

cellStyleBorder.setBorderLeft(CellStyle.BORDER_THIN);

cellStyleBorder.setBorderRight(CellStyle.BORDER_THIN);

cellStyleBorder.setBorderTop(CellStyle.BORDER_THIN);



//这个是从数据库里面查询出来的数据，存放到列表中

//Class log:数据库查询出数据的一个对象

List<Class log> result = new ArrayList<Class log>();



//获得第一个工作区

Sheet sheet = wb.getSheetAt(0);



if (!CommUtils.isNull(result)) {



//循环遍历查询出来的结果对象，写入到excel表格里面去

Integer listSize = result.size();



for (int i = 0; i < listSize; i++) {



Class log = result.get(i);



//因为第一行存放的是列标题，所以从第二行开始写入



//从第二行开始写入

Row row = sheet.createRow(i + 1);



//往表格里面填充数据

Integer cellLeng = log.getClass().getDeclaredFields().length;





for (int cellIndex = 0; cellIndex < cellLeng; cellIndex++) {



//设置excel表格的样式

Cell cell = row.createCell(cellIndex);

if (cellIndex < cellLeng - 1) {

cell.setCellStyle(cellStyleBorder);

}

cell.setCellType(Cell.CELL_TYPE_STRING);



//将第一个数据保存到第一个单元格,依次类推

if (cellIndex == 0) {

String one = log.getXXXXX();

cell.setCellValue(one);

} else if (cellIndex == 1) {

String two = log.getXXXX();

cell.setCellValue(two);

} else if (cellIndex == 2) {

Integer three = log.getXXXXX();

cell.setCellValue(three.toString());

} else if (cellIndex > 2) {

break;

}

}

}

}

//生成导出文件日期

Calendar c = Calendar.getInstance();

String time = c.get(Calendar.YEAR) + "_" + c.get(Calendar.MONTH) + "_" + c.get(Calendar.DATE) + "_" + c.get(Calendar.HOUR) + "_" + c.get(Calendar.MINUTE) + "_" + c.get(Calendar.SECOND);



//生成文件名(以下涉及到文件的输入和输出流)

File excelFile = new File("XXXXX_" + time + ".xls");

FileOutputStream fos = new FileOutputStream(excelFile);

wb.write(fos);

if (!CommUtils.isNull(fos)) {

fos.close();

}

// 读到流中

InputStream inStream = new FileInputStream(excelFile);

// 设置输出的格式

resp.reset();

resp.setContentType("application/x-download; charset=utf-8");

resp.addHeader("Content-Disposition", "attachment; filename=\"" + excelFile + "\"");

// 循环取出流中的数据

byte[] b = new byte[1024];

int len;

try {

OutputStream out = resp.getOutputStream();

while (inStream.read(b) > 0) {

out.write(b);

}

inStream.close();

out.close();

excelFile.delete();

} catch (IOException ex) {

}

}