AJAX+JSP实现基于WEB的文件上传的进度控制(2)
2.1.3. 后台服务类（BackGroundService）
BackGroundService这个Servlet类负责接收Form Post数据、回应状态轮询请求、处理取消文件上传的请求。 尽管可以把这些功能相互分离开来，但为了简单明了，还是将它们放到Servlet中，只是由不同的方法进行分割。 源代码如下：
/** * 本例程演示了通过Web上传文件过程中的进度显示。您可以对本例程进行任何修改和使用。 * 如果需要转载本例程，请您注明作者。 * * 作者： 刘作晨 * EMail:liuzuochen@gmail.com */package liuzuochen.sample.upload;/** * Title: 后台服务 * * Description: 为客户端提供上传及文件传输状态查询服务 * */import java.io.File;import java.io.IOException;import java.util.List;import javax.servlet.ServletException;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.apache.commons.fileupload.FileItem;import org.apache.commons.fileupload.FileUploadException;import org.apache.commons.fileupload.disk.DiskFileItemFactory;import org.apache.commons.fileupload.servlet.*;public class BackGroundService extends javax.servlet.http.HttpServlet implements???????? javax.servlet.Servlet {???? public static final String UPLOAD_DIR = "/upload";???? public static final String DEFAULT_UPLOAD_FAILURE_URL = "./result.jsp";???? public BackGroundService() {???????? super();???? }???? protected void doGet(HttpServletRequest request,????????????????????????? HttpServletResponse response) throws ServletException,???????????? IOException {???????? doPost(request, response);???? }???? /**????? * 从文件路径中取出文件名????? */???? private String takeOutFileName(String filePath) {???????? int pos = filePath.lastIndexOf(File.separator);???????? if (pos > 0) {???????????? return filePath.substring(pos + 1);???????? } else {???????????? return filePath;???????? }???? }???? /**????? * 从request中取出FileUploadStatus Bean????? */???? public static FileUploadStatus getStatusBean(???????????? HttpServletRequest request) {???????? BeanControler beanCtrl = BeanControler.getInstance();???????? return beanCtrl.getUploadStatus(request.getRemoteAddr());???? }???? /**????? * 把FileUploadStatus Bean保存到类控制器BeanControler????? */???? public static void saveStatusBean(???????????? HttpServletRequest request,???????????? FileUploadStatus statusBean) {???????? statusBean.setUploadAddr(request.getRemoteAddr());???????? BeanControler beanCtrl = BeanControler.getInstance();???????? beanCtrl.setUploadStatus(statusBean);???? }???? /**????? * 删除已经上传的文件????? */???? private void deleteUploadedFile(HttpServletRequest request) {???????? FileUploadStatus satusBean = getStatusBean(request);???????? for (int i = 0; i < satusBean.getUploadFileUrlList().size(); i++) {???????????? File uploadedFile = new File(request.getRealPath(UPLOAD_DIR) +????????????????????????????????????????? File.separator +????????????????????????????????????????? satusBean.getUploadFileUrlList().????????????????????????????????????????? get(i));???????????? uploadedFile.delete();???????? }???????? satusBean.getUploadFileUrlList().clear();???????? satusBean.setStatus("删除已上传的文件");???????? saveStatusBean(request, satusBean);???? }???? /**????? * 上传过程中出错处理????? */???? private void uploadExceptionHandle(???????????? HttpServletRequest request,???????????? String errMsg) throws ServletException, IOException {???????? //首先删除已经上传的文件???????? deleteUploadedFile(request);???????? FileUploadStatus satusBean = getStatusBean(request);???????? satusBean.setStatus(errMsg);???????? saveStatusBean(request, satusBean);???? }???? /**????? * 初始化文件上传状态Bean????? */???? private FileUploadStatus initStatusBean(HttpServletRequest???????????? request) {???????? FileUploadStatus satusBean = new FileUploadStatus();???????? satusBean.setStatus("正在准备处理");???????? satusBean.setUploadTotalSize(request.getContentLength());???????? satusBean.setProcessStartTime(System.currentTimeMillis());???????? satusBean.setBaseDir(request.getContextPath() + UPLOAD_DIR);???????? return satusBean;???? }???? /**????? * 处理文件上传????? */???? private void processFileUpload(HttpServletRequest request,??????????????????????????????????? HttpServletResponse response) throws???????????? ServletException, IOException {???????? DiskFileItemFactory factory = new DiskFileItemFactory();???????? //设置内存缓冲区，超过后写入临时文件???????? factory.setSizeThreshold(10240000);???????? //设置临时文件存储位置???????? factory.setRepository(new File(request.getRealPath("/upload/temp")));???????? ServletFileUpload upload = new ServletFileUpload(factory);???????? //设置单个文件的最大上传值???????? upload.setFileSizeMax(102400000);???????? //设置整个request的最大值???????? upload.setSizeMax(102400000);???????? upload.setProgressListener(new FileUploadListener(request));???????? //保存初始化后的FileUploadStatus Bean???????? saveStatusBean(request, initStatusBean(request));???????? String forwardURL = "";???????? try {???????????? List items = upload.parseRequest(request);???????????? //获得返回url???????????? for (int i = 0; i < items.size(); i++) {???????????????? FileItem item = (FileItem) items.get(i);???????????????? if (item.isFormField()) {???????????????????? forwardURL = item.getString();???????????????????? break;???????????????? }???????????? }???????????? //处理文件上传???????????? for (int i = 0; i < items.size(); i++) {???????????????? FileItem item = (FileItem) items.get(i);???????????????? //取消上传???????????????? if (getStatusBean(request).getCancel()) {???????????????????? deleteUploadedFile(request);???????????????????? break;???????????????? }???????????????? //保存文件???????????????? else if (!item.isFormField() && item.getName().length() > 0) {???????????????????? String fileName = takeOutFileName(item.getName());???????????????????? File uploadedFile = new File(request.getRealPath(UPLOAD_DIR) +????????????????????????????????????????????????? File.separator + fileName);???????????????????? item.write(uploadedFile);???????????????????? //更新上传文件列表???????????????????? FileUploadStatus satusBean =???????????????????????????? getStatusBean(request);???????????????????? satusBean.getUploadFileUrlList().add(fileName);???????????????????? saveStatusBean(request, satusBean);???????????????????? Thread.sleep(500);???????????????? }???????????? }???????? } catch (FileUploadException e) {???????????? uploadExceptionHandle(request, "上传文件时发生错误:" + e.getMessage());???????? } catch (Exception e) {???????????? uploadExceptionHandle(request, "保存上传文件时发生错误:" + e.getMessage());???????? }???????? if (forwardURL.length() == 0) {???????????? forwardURL = DEFAULT_UPLOAD_FAILURE_URL;???????? }???????? request.getRequestDispatcher(forwardURL).forward(request, response);???? }???? /**????? * 回应上传状态查询????? */???? private void responseStatusQuery(HttpServletRequest request,?????????????????????????????????????????????? HttpServletResponse response) throws???????????? IOException {???????? response.setContentType("text/xml");???????? response.setHeader("Cache-Control", "no-cache");???????? FileUploadStatus satusBean = getStatusBean(request);???????? response.getWriter().write(satusBean.toJSon());???? }???? /**????? * 处理取消文件上传????? */???? private void processCancelFileUpload(HttpServletRequest request,????????????????????????????????????????? HttpServletResponse response) throws???????????? IOException {???????? FileUploadStatus satusBean = getStatusBean(request);???????? satusBean.setCancel(true);???????? saveStatusBean(request, satusBean);???????? responseStatusQuery(request, response);???? }???? protected void doPost(HttpServletRequest request,?????????????????????????? HttpServletResponse response) throws ServletException,???????????? IOException {???????? boolean isMultipart = ServletFileUpload.isMultipartContent(request);???????? if (isMultipart) {???????????? processFileUpload(request, response);???????? } else {???????????? request.setCharacterEncoding("UTF-8");???????????? if (request.getParameter("uploadStatus") != null) {???????????????? responseStatusQuery(request, response);???????????? }???????????? if (request.getParameter("cancelUpload") != null) {???????????????? processCancelFileUpload(request, response);???????????? }???????? }???? }}整个程序到这里就介绍完了，希望它多少能为您的工作或学习带来点儿帮助。
1 楼 mogui258 2010-08-22 没看见源码啊？