Servlet只读取Excel文件的前两行
我是一个Java初学者尝试使用Apache POI上传.xls文件。 该文件正在上传完全，但不幸的是只有前两行插入数据库，我想所有的行。 我debugging了代码，发现从第二行完成数据parsing后，抛出错误： java.lang.IllegalStateException: Cannot forward after response has been committed 。
package com; public class FileUploadServlet extends HttpServlet { private static final long serialVersionUID = 1L; private static final String UPLOAD_DIRECTORY = "upload"; private static final int THRESHOLD_SIZE = 1024 * 1024 * 3; // 3MB private static final int MAX_FILE_SIZE = 1024 * 1024 * 40; // 40MB private static final int MAX_REQUEST_SIZE = 1024 * 1024 * 50; // 50MB protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // checks if the request actually contains upload file if (!ServletFileUpload.isMultipartContent(request)) { PrintWriter writer = response.getWriter(); writer.println("Request does not contain upload data"); writer.flush(); return; } // configures upload settings DiskFileItemFactory factory = new DiskFileItemFactory(); factory.setSizeThreshold(THRESHOLD_SIZE); factory.setRepository(new File(System.getProperty("java.io.tmpdir"))); ServletFileUpload upload = new ServletFileUpload(factory); upload.setFileSizeMax(MAX_FILE_SIZE); upload.setSizeMax(MAX_REQUEST_SIZE); // constructs the directory path to store upload file String uploadPath = getServletContext().getRealPath("") + File.separator + UPLOAD_DIRECTORY; // creates the directory if it does not exist File uploadDir = new File(uploadPath); if (!uploadDir.exists()) { uploadDir.mkdir(); } try { // parses the request's content to extract file data List formItems = upload.parseRequest(request); Iterator iter = formItems.iterator(); // iterates over form's fields while (iter.hasNext()) { FileItem item = (FileItem)iter.next(); // processes only fields that are not form fields if (!item.isFormField()) { String fileName = new File(item.getName()).getName(); String filePath = uploadPath + File.separator + fileName; File storeFile = new File(filePath); System.out.println("Uploaded at " + filePath); // saves the file on disk item.write(storeFile); File file = new File(filePath); InputStream input = new BufferedInputStream(new FileInputStream(file)); POIFSFileSystem fs = new POIFSFileSystem(input); HSSFWorkbook wb = new HSSFWorkbook(fs); HSSFSheet sheet = wb.getSheetAt(0); //int i = 0; Iterator rows = sheet.rowIterator(); while (rows.hasNext()) { List list = new ArrayList(); HSSFRow row = (HSSFRow)rows.next(); System.out.println("\n"); Iterator cells = row.cellIterator(); while (cells.hasNext()) { HSSFCell cell = (HSSFCell)cells.next(); if (HSSFCell.CELL_TYPE_NUMERIC == cell.getCellType()) { System.out.print(cell.getNumericCellValue() + " "); list.add(cell.getNumericCellValue()); } else if (HSSFCell.CELL_TYPE_STRING == cell.getCellType()) { System.out.print(cell.getStringCellValue() + " "); list.add(cell.getStringCellValue()); } else if (HSSFCell.CELL_TYPE_BOOLEAN == cell.getCellType()) { System.out.print(cell.getBooleanCellValue() + " "); list.add(cell.getBooleanCellValue()); } else if (HSSFCell.CELL_TYPE_BLANK == cell.getCellType()) { System.out.print("BLANK "); } else System.out.print("Unknown cell type"); } insertRowInDB(request,response,list); } } } } catch (Exception ex) { request.setAttribute("message", "There was an error: " + ex.getMessage()); } } public void insertRowInDB(HttpServletRequest request, HttpServletResponse response, List cellValues) throws ServletException, IOException { response.setContentType("text/html"); PrintWriter out = response.getWriter(); Connection con = null; PreparedStatement psmt = null; try { Class.forName("com.mysql.jdbc.Driver"); psmt = (PreparedStatement)con.prepareStatement("INSERT INTO lillyTT" + " VALUES(?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)"); int paramIndex = 1; for (Object cell : cellValues) { psmt.setObject(paramIndex, cell); paramIndex++; } int status = psmt.executeUpdate(); if (status > 0) { System.out.println("successful"); RequestDispatcher rd = request.getRequestDispatcher("SelectOption.jsp"); rd.forward(request, response); } } catch(SQLException ex) { ex.printStackTrace(); /* log the exception */ } catch (ClassNotFoundException e) { e.printStackTrace(); } finally { try { out.close(); psmt.close(); con.close(); } catch(SQLException ignored) { } } } }
这是因为每次调用insertRowInDB() ，方法都是使用PrintWriter编写响应，您只能发送一次响应。 尝试删除它。