文件上传限制文件类型

public class FileUploadManager {
    /** 允许上传的扩展名*/  
    public static String [] extensionPermit = {"txt", "xls", "zip"}; 

    public FileUploadManager(User user, HttpServletRequest request) throws Exception {
        super();
        session = request.getSession();
        DiskFileItemFactory factory = new DiskFileItemFactory();
        upload = new ServletFileUpload(factory);
        SystemManager systemManager = ComponentFactory.getSystemManager();
        int docSize = Integer.parseInt(systemManager.getSystemConfig(user.getCompanyID(), "DOCUMENT_SIZE_LIMIT").getValue());
        int maxFileSize = 1024 * 1024 * docSize;
        upload.setFileSizeMax(maxFileSize); // 设置单个文件的最大上传大小
        upload.setSizeMax(maxFileSize + 500); // 设置整个request的最大大小
        upload.setProgressListener(new FileUploadListener(request));
        extensionPermit = systemManager.getSystemConfig(user.getCompanyID(), "DOCUMENT_EXT_LIMIT").getValue().split(",");//设置文件类型
        files = upload.parseRequest(request);
    }


class QCServletFileUpload extends ServletFileUpload {
    private Map textHash = new HashMap();//表单数据
    private int fileItemCount = 0;

    // 重载parseRequest方法
    public List parseRequest(HttpServletRequest request) throws FileUploadException {
        List items = new ArrayList();//文件
        try {
            FileItemIterator iter = getItemIterator(request);
            FileItemFactory fac = getFileItemFactory();
            while (iter.hasNext()) {
                FileItemStream item = iter.next();
                FileItem fileItem = fac.createItem(item.getFieldName(), item.getContentType(), item.isFormField(), item.getName());
                Streams.copy(item.openStream(), fileItem.getOutputStream(), true);
                //fileItem.getOutputStream().close();
                if (fileItem.isFormField()) { // 处理form field
                    textHash.put(fileItem.getFieldName(), fileItem);
                } else if (fileItem.getName() != null && fileItem.getName().length() > 0) {// 处理file field
                    String fileExtension = FilenameUtils.getExtension(fileItem.getName());
                    if(!ArrayUtils.contains(FileUploadManager.extensionPermit, fileExtension)){
                        fileItemCount++;
                        items.add(fileItem);
                    }else{
                        throw new FileUploadException("文件" + fileItem.getName() + "类型不支持.");
                    }
                    
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
            throw new FileUploadException(e.getMessage(), e);
        }
        return items;
    }

}