poi excel download

poi excel download

1. Declare the browser type: application/vnd.ms-excel

public static final String XLS = "application/vnd.ms-excel";

2. Create Excel

//create EXCEL
			HSSFWorkbook wb = new HSSFWorkbook();  
		        HSSFSheet sheet = wb.createSheet("Leave Statistics");  
		        HSSFRow row = sheet.createRow((int) 0);  
		        HSSFCellStyle style = wb.createCellStyle();  
		        style.setAlignment(HSSFCellStyle.ALIGN_CENTER);
				
		        //Create Excel header file
		        int i = 0;
		        for(Map.Entry<String, String> entry : exportExcelFields().entrySet()){
		        	 HSSFCell cell = row.createCell(i);  
		        	 String value = entry.getValue();
System.out.println("value====="+value);
		        	 cell.setCellValue(value);  
		             cell.setCellStyle(style);
		             sheet.autoSizeColumn(i);
		             sheet.setColumnWidth(i, 5000);
		        	 i++;
		        }
		        
		        //create data
				if(null!=users && users.size()>0){
					i=1;
			        for(User user : users){
			        	Map<String,Object> map = (Map<String,Object>) JSONObject.fromObject(user);
			        	row = sheet.createRow(i);
			        	int j = 0;
			        	for(Map.Entry<String, String> entry : exportExcelFields().entrySet()){
			        		String key = entry.getKey();
			        		String value = map.get(key)==null?"":String.valueOf(map.get(key));
System.out.println("key=========="+key+"         value====="+value);
			        		if("sex".equals(key)) row.createCell(j).setCellValue("F".equals(value.toUpperCase())?'女' : '男');
			        		else row.createCell(j).setCellValue(value);
			        		sheet.autoSizeColumn (j);
			        		j++;
			        	}
			        	i++;
			        }
				}
				this.writeExcel(response, wb, "leave statistics.xls");

3. The response to the client has been streamed

public static void writeExcel(HttpServletResponse response, HSSFWorkbook workbook, String filename) throws IOException {
	ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
	workbook.write(byteArrayOutputStream);
	byte[] bytes = byteArrayOutputStream.toByteArray();
	// clear the response
	response.reset();
	// Set the Header of the response
	response.setContentType(XLS+";charset=utf-8");
	response.addHeader("Content-Disposition", "attachment;filename=" + new String (filename.getBytes("utf-8"),"iso8859-1"));
	response.addHeader("Content-Length", "" + bytes.length);
	OutputStream outputStream = new BufferedOutputStream(response.getOutputStream());
	outputStream.write(bytes);
	outputStream.flush();
	outputStream.close();
}