ajax基础概念.核心技术与典型案例

package book.ch20; import java.io.*; import java.util.Iterator; import java.util.List; import javax.servlet.ServletException; import javax.servlet.http.*; import org.apache.commons.fileupload.*; import org.apache.commons.fileupload.servlet.ServletFileUpload; public class UploadServlet extends HttpServlet { public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { // 创建HttpSession对象 HttpSession session = request.getSession(); if ("status".equals(request.getParameter("c"))) {// 如果请求中c的值为status doStatus(session, response);// 调用doStatus方法 } else {// 否则，调用doFileUpload方法 doFileUpload(session, request, response); } } public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { doPost(request, response); } private void doFileUpload(HttpSession session, HttpServletRequest request, HttpServletResponse response) throws IOException { try { // 创建UploadListener对象 UploadListener listener = new UploadListener(request .getContentLength()); listener.start();// 启动监听状态 // 将监听器对象的状态保存在Session中 session.setAttribute("FILE_UPLOAD_STATS", listener .getFileUploadStats()); // 创建MonitoredDiskFileItemFactory对象 FileItemFactory factory = new MonitoredDiskFileItemFactory(listener); // 通过该工厂对象创建ServletFileUpload对象 ServletFileUpload upload = new ServletFileUpload(factory); // 将转化请求保存到list对象中 List items = upload.parseRequest(request); // 停止使用监听器 listener.done(); boolean hasError = false; // 循环list中的对象 for (Iterator i = items.iterator(); i.hasNext();) { FileItem fileItem = (FileItem) i.next(); if (!fileItem.isFormField()) {// 如果该FileItem不是表单域 processUploadedFile(fileItem);// 调用processUploadedFile方法,将数据保存到文件中 fileItem.delete();// 内存中删除该数据流 } } if (!hasError) {// 如果没有出现错误 sendCompleteResponse(response, null);// 调用sendCompleteResponse方法 } else { sendCompleteResponse(response, "Could not process uploaded file. Please see log for details."); } } catch (Exception e) { sendCompleteResponse(response, e.getMessage()); } } public void processUploadedFile(FileItem item) { // 获得上传文件的文件名 String fileName = item.getName().substring( item.getName().lastIndexOf("\\") + 1); // 创建File对象,将上传的文件保存到C:\\upload文件夹下 File file = new File("C:\\upload\\", fileName); InputStream in; try { in = item.getInputStream();// 获得输入数据流文件 // 将该数据流写入到指定文件中 FileOutputStream out = new FileOutputStream(file); byte[] buffer = new byte[4096]; // To hold file contents int bytes_read; while ((bytes_read = in.read(buffer)) != -1) // Read until // EOF { out.write(buffer, 0, bytes_read); } if (in != null) try { in.close(); } catch (IOException e) { ; } if (out != null) try { out.close(); } catch (IOException e) { ; } } catch (IOException e1) { e1.printStackTrace(); } } private void doStatus(HttpSession session, HttpServletResponse response) throws IOException { // 设置该响应不在缓存中读取 response.addHeader("Expires", "0"); response.addHeader("Cache-Control", "no-store, no-cache, must-revalidate"); response.addHeader("Cache-Control", "post-check=0, pre-check=0"); response.addHeader("Pragma", "no-cache"); // 获得保存在Session中的状态信息 UploadListener.FileUploadStats fileUploadStats = (UploadListener.FileUploadStats) session .getAttribute("FILE_UPLOAD_STATS"); if (fileUploadStats != null) { long bytesProcessed = fileUploadStats.getBytesRead();// 获得已经上传的数据大小 long sizeTotal = fileUploadStats.getTotalSize();// 获得上传文件的总大小 // 计算上传完成的百分比 long percentComplete = (long) Math .floor(((double) bytesProcessed / (double) sizeTotal) * 100.0); // 获得上传已用的时间 long timeInSeconds = fileUploadStats.getElapsedTimeInSeconds(); // 计算平均上传速率 double uploadRate = bytesProcessed / (timeInSeconds + 0.00001); // 计算总共所需时间 double estimatedRuntime = sizeTotal / (uploadRate + 0.00001); // 将上传状态返回给客户端 response.getWriter().println("<b>Upload Status:</b><br/>"); if (fileUploadStats.getBytesRead() != fileUploadStats .getTotalSize()) { response.getWriter().println( "<div class=\"prog-border\"><div class=\"prog-bar\" style=\"width: " + percentComplete + "%;\"></div></div>"); response.getWriter().println( "Uploaded: " + bytesProcessed + " out of " + sizeTotal + " bytes (" + percentComplete + "%) " + (long) Math.round(uploadRate / 1024) + " Kbs <br/>"); response.getWriter().println( "Runtime: " + formatTime(timeInSeconds) + " out of " + formatTime(estimatedRuntime) + " " + formatTime(estimatedRuntime - timeInSeconds) + " remaining <br/>"); } else { response.getWriter().println( "Uploaded: " + bytesProcessed + " out of " + sizeTotal + " bytes<br/>"); response.getWriter().println("Complete.<br/>"); } } // 如果文件已经上传完毕 if (fileUploadStats != null && fileUploadStats.getBytesRead() == fileUploadStats .getTotalSize()) { response.getWriter().println("<b>Upload complete.</b>"); } } private void sendCompleteResponse(HttpServletResponse response, String message) throws IOException { if (message == null) { response .getOutputStream() .print( "<html><head><script type='text/ javascript'> function killUpdate() { window.parent.killUpdate(''); }</script></head><body onload='killUpdate()'></body></html>"); } else { response .getOutputStream() .print( "<html><head><script type='text/ javascript'>function killUpdate() { window.parent.killUpdate('" + message + "'); }</script></head><body onload='killUpdate()'></body></html>"); } } private String formatTime(double timeInSeconds) { long seconds = (long) Math.floor(timeInSeconds); long minutes = (long) Math.floor(timeInSeconds / 60.0); long hours = (long) Math.floor(minutes / 60.0); if (hours != 0) { return hours + "hours " + (minutes % 60) + "minutes " + (seconds % 60) + "seconds"; } else if (minutes % 60 != 0) { return (minutes % 60) + "minutes " + (seconds % 60) + "seconds"; } else { return (seconds % 60) + " seconds"; } } }