Apache POI生成Excel
public InputStream getInputStream(){HSSFWorkbook wb = new HSSFWorkbook();HSSFSheet sheet = wb.createSheet("sheet1");HSSFRow row = sheet.createRow(0);HSSFCell cell = row.createCell((short) 0);cell.setEncoding(HSSFCell.ENCODING_UTF_16);cell.setCellValue("序号");cell = row.createCell((short) 1);cell.setEncoding(HSSFCell.ENCODING_UTF_16);cell.setCellValue("姓");cell = row.createCell((short) 2);cell.setEncoding(HSSFCell.ENCODING_UTF_16);cell.setCellValue("名");cell = row.createCell((short) 3);cell.setEncoding(HSSFCell.ENCODING_UTF_16);cell.setCellValue("年龄");List<User> list = this.findAll();for (int i = 0; i < list.size(); ++i){User user = list.get(i);row = sheet.createRow(i + 1);cell = row.createCell((short) 0);cell.setEncoding(HSSFCell.ENCODING_UTF_16);cell.setCellValue(i + 1);cell = row.createCell((short) 1);cell.setEncoding(HSSFCell.ENCODING_UTF_16);cell.setCellValue(user.getFirstname());cell = row.createCell((short) 2);cell.setEncoding(HSSFCell.ENCODING_UTF_16);cell.setCellValue(user.getLastname());cell = row.createCell((short) 3);cell.setEncoding(HSSFCell.ENCODING_UTF_16);cell.setCellValue(user.getAge());}File file = new File("test.xls");try{OutputStream os = new FileOutputStream(file);wb.write(os);os.close();}catch (Exception e){e.printStackTrace();}InputStream is = null;try{is = new FileInputStream(file);}catch (FileNotFoundException e){e.printStackTrace();}return is;}上面在服务器端生成test.xls时这样会造成多用户不同步的情况。
解决办法：
1.让每个用户产生一个随机名字的文件
bug：多个用户的话，这样的垃圾文件会越来越多。
所以，当用户下载完后，过一段时间就将他删掉。
生成一个文件后通过线程将文件删除。
new Thread(new Runnable(){public void run(){try{Thread.sleep(15000);}catch (InterruptedException e){e.printStackTrace();}file.delete();//删除临时文件 }}).start();
或者服务器启动就删除
web.xml
<servlet> <servlet-name>DeleteFilesServlet</servlet-name> <servlet-class>com.test.servlet.DeleteFilesServlet</servlet-class> <!-- 这个是用来server自动访问,不需要urlmapping --> <load-on-startup>8</load-on-startup></servlet>
public class DeleteFilesServlet extends HttpServlet{public void destroy(){}public void init() throws ServletException{//File file = new File(".");////File[] subFiles = file.listFiles();////for(File f : subFiles)//{//if(f.getName().endsWith("xls"))//{//f.delete();//}//}File file = new File(".");File[] subFiles = file.listFiles(new FileFilter(){public boolean accept(File pathname){if(pathname.getName().endsWith("xls")){return true;}return false;}});for(File f : subFiles){f.delete();}}}
2.将构造好的流放到内存里，不会在服务
器端产生大量的临时文件。
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