Ajax + servlet 实现上传进度条显示

package myupload.progressbar; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.util.Iterator; import java.util.List; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.commons.fileupload.FileItem; import org.apache.commons.fileupload.FileItemFactory; import org.apache.commons.fileupload.FileUploadException; import org.apache.commons.fileupload.disk.DiskFileItemFactory; import org.apache.commons.fileupload.servlet.ServletFileUpload; public class Upload extends HttpServlet { public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("GBK"); response.setContentType("text;charset=ISO-8859-1"); if ("status".equalsIgnoreCase(request.getParameter("status"))) { status(response); } else { totalSize = request.getContentLength(); try { upload(request); } catch (FileUploadException e) { e.printStackTrace(); } } } private void upload(HttpServletRequest request) throws FileUploadException, IOException { FileItemFactory factory = new DiskFileItemFactory(); ServletFileUpload upload = new ServletFileUpload(factory); List items = upload.parseRequest(request); for (Iterator it = items.iterator(); it.hasNext();) { FileItem fileItem = (FileItem) it.next(); if (!fileItem.isFormField()) { String fileName = fileItem.getName().substring( fileItem.getName().lastIndexOf("\\") + 1); File file = new File("C:/", fileName); InputStream in = fileItem.getInputStream(); FileOutputStream out = new FileOutputStream(file); byte[] buffer = new byte[2048]; int n; while ((n = in.read(buffer)) != -1) { out.write(buffer, 0, n); completedSize += (long) n; } fileItem.delete(); } } totalSize = completedSize = 0L; } private void status(HttpServletResponse response) throws IOException { long lastSeconds = (System.currentTimeMillis() - startTime) / 1000; double percentd = (double) (completedSize * 100) / (double) (totalSize + 0.0001); int percent = (int) (percentd); int uploadSpeed = (int) (completedSize / (lastSeconds + 0.0001)); System.out.print("lastSeconds:" + lastSeconds + "\tuploadSpeed:" + uploadSpeed + "\tpercent:" + percent); System.out.println("\tcompletedSize:" + completedSize + "\ttotalSize:" + totalSize); response.getWriter().print(percent); } public void init() throws ServletException { totalSize = 0L; completedSize = 0L; startTime = System.currentTimeMillis(); } private long totalSize = 0L; private long completedSize = 0L; private long startTime = 0L; }