文件上传 含进度条（fileupload控件）

<span style="font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);">之前的项目一直没有涉及到达的文件上传，所以没有用到进度条，这几天不忙，所以想把这个功能实现一下，我用的的fileupload的上传控件，在网上查了一下，基本也都用这个，它可以上传一个或者多个文件。</span>

fileupload将获取的表单内容分为了多个fileitem,fileitem大致分为两类，formfeild和非formfield.

主要是formfield的操作.这时的form定义entype 为enctype="multipart/form-data"。

resp.setContentType("text/html;charset=UTF-8");  //设置处理请求的编码方式req.setCharacterEncoding("UTF-8");        PrintWriter pw = resp.getWriter();  DiskFileItemFactory factory = new DiskFileItemFactory();factory.setSizeThreshold(2048*1024);

这里request.setCharacterEncoding()是设置文件上传的编码方式，如果不设置这个，上传文件名为汉字的将显示乱码。

DIskFileItemFactory是生成servletFileUpload的前提，这是工厂模式的，

factory.setSizeThreshold(2048*1024);设置文件上传时缓存区的大小，当缓存区满了以后文件江北上传到内存中。

ServletFileUpload upload = new ServletFileUpload(factory);

myProgressListener getBarListener = new myProgressListener(req);

upload.setProgressListener(getBarListener);//上传大的文件就需要进度条的显示，这里是给对象添加监听器

注册了监听器后，文件上传中，监听器会时时侦听对象的上传情况，为了绘制进度条，这里将侦听到的情况放在session中，然后ajax开启另一个servelt每秒去获取一次session,并且将session中的对象以json形式返回到前端绘制进度条。

说这么多直接上源码

public class myProgressListener implements ProgressListener {private HttpSession session;public myProgressListener(HttpServletRequest req) {session=req.getSession();fileUploadStatus status = new fileUploadStatus();session.setAttribute("status", status);}/* pBytesRead  到目前为止读取文件的比特数 * pContentLength 文件总大小 * pItems 目前正在读取第几个文件 */public void update(long pBytesRead, long pContentLength, int pItems) {// TODO Auto-generated method stubfileUploadStatus status = (fileUploadStatus) session.getAttribute("status");status.setPBytesRead(pBytesRead);status.setPContentLength(pContentLength);status.setPItems(pItems);}

uolpadServlet

protected void doPost(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {resp.setContentType("text/html;charset=UTF-8");  //设置处理请求的编码方式req.setCharacterEncoding("UTF-8");        PrintWriter pw = resp.getWriter();  DiskFileItemFactory factory = new DiskFileItemFactory();factory.setSizeThreshold(2048*1024);myProgressListener getBarListener = new myProgressListener(req);ServletFileUpload upload = new ServletFileUpload(factory);upload.setProgressListener(getBarListener);//upload.setHeaderEncoding("UTF-8");try {List formList = upload.parseRequest(req);Iterator<Object> formItem = formList.iterator();// 将进度监听器加载进去while (formItem.hasNext()) {FileItem item = (FileItem) formItem.next();if (item.isFormField()) { System.out.println("处理表单内容 ...");  //System.out.println("处理表单内容 ...");  processFormField(item, pw);  //System.out.println("Field Name:" + item.getFieldName());} else { System.out.println("处理上传的文件 ...");   // 此时的文件名包含了完整的路径，得注意加工一下 String fileName = item.getName().substring(item.getName().lastIndexOf("\\")+1);File file = new File("d:\\temp"+ "\\" + fileName);System.out.println("d:\\temp"+ "\\" + fileName);//if(new File(fileName).exists()){OutputStream out = item.getOutputStream();InputStream in = item.getInputStream();req.getSession().setAttribute("outPutStream", out);req.getSession().setAttribute("inPutStream", in);item.write(file);pw.println(fileName + " 文件保存完毕 ...");          pw.println("文件大小为 ：" + item.getSize() + "\r\n"); /*}else{System.out.println("该文件已经存在，请重新上传");}*/}}} catch (FileUploadException e2) {// TODO Auto-generated catch blocke2.printStackTrace();} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}} // 处理表单内容      private void processFormField(FileItem item, PrintWriter pw)          throws Exception      {          String name = item.getFieldName();          String value = item.getString();                  pw.println(name + " : " + value + "\r\n");      }  

progreeServlet

public void doPost(HttpServletRequest request, HttpServletResponse response) {HttpSession session = request.getSession();fileUploadStatus status = (fileUploadStatus) session.getAttribute("status");try {response.reset();response.getWriter().write("{\"pBytesRead\":"+status.getPBytesRead()+",\"pContentLength\":"+status.getPContentLength()+"}");System.out.println("{\"pBytesRead\":"+status.getPBytesRead()+",\"pContentLength\":"+status.getPContentLength()+"}");} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}public void doGet(HttpServletRequest request, HttpServletResponse response) {this.doPost(request,response);}}

List formList = upload.parseRequest(req);//fileupload对象解析请求头。

用这个控件上传文件，头设置enctype="multipart/form-data",提交后，文件对象信息会跟在请求投中每个fileitem分开。
Iterator<Object> formItem = formList.iterator();