图片上传源码(commons-fileupload-1.2.2)分析

图片上传源码(commons-fileupload-1.2.2)分析 第一步:生成DiskFileItemFactory 实现接口生成factory DiskFileItemFactory factory = new DiskFileItemFactory(); /** * Constructs an unconfigured instance of this class. The resulting factory * may be configured by calling the appropriate setter methods. */ public DiskFileItemFactory() { this(DEFAULT_SIZE_THRESHOLD, null); } /** * Constructs a preconfigured instance of this class. * * @param sizeThreshold The threshold, in bytes, below which items will be * retained in memory and above which they will be * stored as a file. * @param repository The data repository, which is the directory in * which files will be created, should the item size * exceed the threshold. */ public DiskFileItemFactory(int sizeThreshold, File repository) { this.sizeThreshold = sizeThreshold; this.repository = repository; } 向diskFileItemFctory指定参数 // 设置最多只允许在内存中存储的数据,单位:字节 factory.setSizeThreshold(4096); // 设置一旦文件大小超过getSizeThreshold()(默认10kb)的值时数据存放在硬盘的 factory.setRepository(new File("d:\\temp")); /** * Sets the directory used to temporarily store files that are larger * than the configured size threshold. * * @param repository The directory in which temporary files will be located. * * @see #getRepository() * */ public void setRepository(File repository) { this.repository = repository; } 第二步:生成ServletFileUpload 根据第一步得到的factory生成servletFileUpload对象 /** * Constructs an instance of this class which uses the supplied factory to * create FileItem instances. * * @see FileUpload#FileUpload() * @param fileItemFactory The factory to use for creating file items. */ public ServletFileUpload(FileItemFactory fileItemFactory) { super(fileItemFactory); } 向servletFileUpload对象指定参数 // 设置允许用户上传文件大小,单位:字节，这里设为1m 值为-1没有大小限制 sevletFileUpload.setSizeMax(1 * 1024 * 1024); /** * Sets the maximum allowed size of a complete request, as opposed * to {@link #setFileSizeMax(long)}. * * @param sizeMax The maximum allowed size, in bytes. The default value of * -1 indicates, that there is no limit. * * @see #getSizeMax() * */ public void setSizeMax(long sizeMax) { this.sizeMax = sizeMax; } 第三步:通过servletFileUpload读取request上传信息 List fileItems = sevletFileUpload.parseRequest(req); /** * Processes an * This implementation first attempts to rename the uploaded item to the * specified destination file, if the item was originally written to disk. * Otherwise, the data will be copied to the specified file. *

* This method is only guaranteed to work once, the first time it * is invoked for a particular item. This is because, in the event that the * method renames a temporary file, that file will no longer be available * to copy or rename again at a later time. * * @param file The File into which the uploaded item should * be stored. * * @throws Exception if an error occurs. */ public void write(File file) throws Exception { if (isInMemory()) { FileOutputStream fout = null; try { fout = new FileOutputStream(file); fout.write(get()); } finally { if (fout != null) { fout.close(); } } } else { File outputFile = getStoreLocation(); if (outputFile != null) { // Save the length of the file size = outputFile.length(); /* * The uploaded file is being stored on disk * in a temporary location so move it to the * desired file. */ if (!outputFile.renameTo(file)) { BufferedInputStream in = null; BufferedOutputStream out = null; try { in = new BufferedInputStream( new FileInputStream(outputFile)); out = new BufferedOutputStream( new FileOutputStream(file)); IOUtils.copy(in, out); } finally { if (in != null) { try { in.close(); } catch (IOException e) { // ignore } } if (out != null) { try { out.close(); } catch (IOException e) { // ignore } } } } } else { /* * For whatever reason we cannot write the * file to disk. */ throw new FileUploadException( "Cannot write uploaded file to disk!"); } } } 附后台完整代码: @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { resp.setContentType("text/html; charset=GB2312"); PrintWriter out = resp.getWriter(); HttpSession session = req.getSession(); session.setMaxInactiveInterval(20); String submit = (String) session.getAttribute("submit"); String flag = req.getParameter("flag"); if (flag != null && flag.equals("ajax")) { if (submit != null) { out.print("重复提交"); } } else { AlbumService as = new AlbumService(); // submit=null代

第一次提交，不为null代表重复提交 if (submit == null) { try { DiskFileItemFactory factory = new DiskFileItemFactory(); // 设置最多只允许在内存中存储的数据,单位:字节 factory.setSizeThreshold(4096); // 设置一旦文件大小超过getSizeThreshold()的值时数据存放在硬盘的目录 factory.setRepository(new File("d:\\temp")); ServletFileUpload sevletFileUpload = new ServletFileUpload( factory); // 设置允许用户上传文件大小,单位:字节，这里设为2m 值为-1没有大小限制 sevletFileUpload.setSizeMax(1 * 1024 * 1024); // 开始读取上传信息 List fileItems = sevletFileUpload.parseRequest(req); // 依次处理每个上传的文件 Iterator iter = fileItems.iterator(); // 正则匹配，过滤路径取文件名 String regExp = ".+\\\\(.+)$"; // 过滤掉的文件类型 String[] errorType = { ".exe", ".com", ".cgi", ".asp" }; Pattern p = Pattern.compile(regExp); while (iter.hasNext()) { FileItem item = (FileItem) iter.next(); // 忽略其他不是文件域的所有表单信息 if (!item.isFormField()) { String name = item.getName(); long size = item.getSize(); if ((name == null || name.equals("")) && size == 0) continue; Matcher m = p.matcher(name); boolean result = m.find(); if (result) { for (int temp = 0; temp < errorType.length; temp++) { if (m.group(1).endsWith(errorType[temp])) { throw new IOException(name + ": 非法文件类型禁止上传"); } } try { // 保存上传的文件到指定的目录 // 在下文中上传文件至数据库时，将对这里改写开始 item.write(new File( "D:/WorkSpace/BlogV1.4/WebContent/uploadImages/" + m.group(1))); as.uploadAlbum(m.group(1), req.getContextPath() + "/uploadImages/"); out.print(name + "  " + size + "
"); // 在下文中上传文件至数据库时，将对这里改写结束 } catch (Exception e) { out.println(e); } } else { throw new IOException("fail to upload"); } } } } catch (IOException e) { out.println(e); } catch (FileUploadException e) { out.println(e); } // 最后把session中的值置为false，表示对表单提交做过操作 session.setAttribute("submit", "submit"); List albumList = as.getAlbumList(); req.setAttribute("albumList", albumList); req.getRequestDispatcher("/albumList.jsp").forward(req, resp); } else { out.print("重复提交"); } } } }