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AJAX和JSP实现的基于WEB的文件上传的进度控制代码第1/2页

时间:2021-07-01 10:21:17 帮助过:37人阅读

1.引言
2.实现代码
2.1.服务器端代码
2.1.1. 文件上传状态类(FileUploadStatus)
2.1.2. 文件上传状态侦听类(FileUploadListener)
2.1.3. 后台服务类(BackGroundService)
2.1.4. 文件上传状态控制类(BeanControler)
2.2. 客户端代码
2.2.1. AjaxWrapper.js
2.2.2. fileUpload.html
2.2.3. result.jsp
2.2.4. fileUpload.css
2.3. 配置文件
3. 结语

 1. 引言

   基于浏览器的文件上传,特别是对于通过<input type="file">标签来实现上传的情况, 存在着严重的性能问题,因为用户提交了文件之后,在浏览器把文件上传到服务器的过程中,界面看上去似乎是静止的,如果是小文件还好些,如果不幸需要上传的是几兆、几十兆甚至上百兆的文件,我相信那是一种非常痛苦的体验,我们中间的很多人应该都有过此种不堪的经历。(一笑)

  现在我就针对这个问题给出一个解决方案,我们将实现一个具有监控能力的WEB上传的程序——它不仅把文件上传到服务器,而且"实时地"监视文件上传的实际过程。

解决方案的基本思路是这样的:

  •   在Form提交上传文件同时,使用AJAX周期性地从Servlet轮询上传状态信息
  •   然后,根据此信息更新进度条和相关文字,及时反映文件传输状态
  •   如果用户取消上传操作,则进行相应的现场清理工作:删除已经上传的文件,在Form提交页面中显示相关信息
  •   如果上传完毕,显示已经上传的文件内容(或链接)

在介绍源代码之前,我们先来看看程序运行界面:

 2. 实现代码

   实现代码想当然的有服务器端代码和客户端代码(呵呵),我们先从服务器端开始。

 2.1. 服务器端代码

  2.1.1. 文件上传状态类(FileUploadStatus)

   使用FileUploadStatus这个类记录文件上传状态,并将其作为服务器端与web客户端之间通信的媒介,通过对这个类对象提供上传状态作为服务器回应发送给web客户端, web客户端使用JavaScript获得文件上传状态。源代码如下:

  1. /**
  2. * 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。
  3. * 如果需要转载本例程,请您注明作者。
  4. *
  5. * 作者: 刘作晨
  6. * EMail:liuzuochen@gmail.com
  7. */
  8. package liuzuochen.sample.upload;
  9. import java.util.*;
  10. public class FileUploadStatus {
  11. //上传用户地址
  12. private String uploadAddr;
  13. //上传总量
  14. private long uploadTotalSize = 0;
  15. //读取上传总量
  16. private long readTotalSize = 0;
  17. //当前上传文件号
  18. private int currentUploadFileNum = 0;
  19. //成功读取上传文件数
  20. private int successUploadFileCount = 0;
  21. //状态
  22. private String status = "";
  23. //处理起始时间
  24. private long processStartTime = 0l;
  25. //处理终止时间
  26. private long processEndTime = 0l;
  27. //处理执行时间
  28. private long processRunningTime = 0l;
  29. //上传文件URL列表
  30. private List uploadFileUrlList = new ArrayList();
  31. //取消上传
  32. private boolean cancel = false;
  33. //上传base目录
  34. private String baseDir = "";
  35. public FileUploadStatus() {
  36. }
  37. public String getBaseDir() {
  38. return baseDir;
  39. }
  40. public void setBaseDir(String baseDir) {
  41. this.baseDir = baseDir;
  42. }
  43. public boolean getCancel() {
  44. return cancel;
  45. }
  46. public void setCancel(boolean cancel) {
  47. this.cancel = cancel;
  48. }
  49. public List getUploadFileUrlList() {
  50. return uploadFileUrlList;
  51. }
  52. public void setUploadFileUrlList(List uploadFileUrlList) {
  53. this.uploadFileUrlList = uploadFileUrlList;
  54. }
  55. public long getProcessRunningTime() {
  56. return processRunningTime;
  57. }
  58. public void setProcessRunningTime(long processRunningTime) {
  59. this.processRunningTime = processRunningTime;
  60. }
  61. public long getProcessEndTime() {
  62. return processEndTime;
  63. }
  64. public void setProcessEndTime(long processEndTime) {
  65. this.processEndTime = processEndTime;
  66. }
  67. public long getProcessStartTime() {
  68. return processStartTime;
  69. }
  70. public void setProcessStartTime(long processStartTime) {
  71. this.processStartTime = processStartTime;
  72. }
  73. public long getReadTotalSize() {
  74. return readTotalSize;
  75. }
  76. public void setReadTotalSize(long readTotalSize) {
  77. this.readTotalSize = readTotalSize;
  78. }
  79. public int getSuccessUploadFileCount() {
  80. return successUploadFileCount;
  81. }
  82. public void setSuccessUploadFileCount(int successUploadFileCount) {
  83. this.successUploadFileCount = successUploadFileCount;
  84. }
  85. public int getCurrentUploadFileNum() {
  86. return currentUploadFileNum;
  87. }
  88. public void setCurrentUploadFileNum(int currentUploadFileNum) {
  89. this.currentUploadFileNum = currentUploadFileNum;
  90. }
  91. public String getStatus() {
  92. return status;
  93. }
  94. public void setStatus(String status) {
  95. this.status = status;
  96. }
  97. public long getUploadTotalSize() {
  98. return uploadTotalSize;
  99. }
  100. public String getUploadAddr() {
  101. return uploadAddr;
  102. }
  103. public void setUploadTotalSize(long uploadTotalSize) {
  104. this.uploadTotalSize = uploadTotalSize;
  105. }
  106. public void setUploadAddr(String uploadAddr) {
  107. this.uploadAddr = uploadAddr;
  108. }
  109. public String toJSon() {
  110. StringBuffer strJSon = new StringBuffer();
  111. strJSon.append("{UploadTotalSize:").append(getUploadTotalSize()).append(
  112. ",")
  113. .append("ReadTotalSize:").append(getReadTotalSize()).append(",")
  114. .append("CurrentUploadFileNum:").append(getCurrentUploadFileNum()).
  115. append(",")
  116. .append("SuccessUploadFileCount:").append(
  117. getSuccessUploadFileCount()).append(",")
  118. .append("Status:'").append(getStatus()).append("',")
  119. .append("ProcessStartTime:").append(getProcessStartTime()).
  120. append(",")
  121. .append("ProcessEndTime:").append(getProcessEndTime()).append(
  122. ",")
  123. .append("ProcessRunningTime:").append(getProcessRunningTime()).
  124. append(",")
  125. .append("Cancel:").append(getCancel()).append("}");
  126. return strJSon.toString();
  127. }
  128. }

  2.1.2. 文件上传状态侦听类(FileUploadListener)

   使用Common-FileUpload 1.2版本(20070103)。此版本提供了能够监视文件上传情况的ProcessListener接口,使开发者通过FileUploadBase类对象的setProcessListener方法植入自己的Listener。 FileUploadListener类实现了ProcessListener,在整个文件上传过程中,它对上传进度进行监控,并且根据上传 情况实时的更新上传状态Bean。源代码如下:

  1. /**
  2. * 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。
  3. * 如果需要转载本例程,请您注明作者。
  4. *
  5. * 作者: 刘作晨
  6. * EMail:liuzuochen@gmail.com
  7. */
  8. package liuzuochen.sample.upload;
  9. import org.apache.commons.fileupload.ProgressListener;
  10. import javax.servlet.http.HttpServletRequest;
  11. public class FileUploadListener implements ProgressListener{
  12. private HttpServletRequest request=null;
  13. public FileUploadListener(HttpServletRequest request){
  14. this.request=request;
  15. }
  16. /**
  17. * 更新状态
  18. */
  19. public void update(long pBytesRead, long pContentLength, int pItems){
  20. FileUploadStatus statusBean= BackGroundService.getStatusBean(request);
  21. statusBean.setUploadTotalSize(pContentLength);
  22. //读取完成
  23. if (pContentLength == -1) {
  24. statusBean.setStatus("完成对" + pItems +"个文件的读取:读取了 " + pBytesRead + " bytes.");
  25. statusBean.setReadTotalSize(pBytesRead);
  26. statusBean.setSuccessUploadFileCount(pItems);
  27. statusBean.setProcessEndTime(System.currentTimeMillis());
  28. statusBean.setProcessRunningTime(statusBean.getProcessEndTime());
  29. //读取中
  30. } else {
  31. statusBean.setStatus("当前正在处理第" + pItems +"个文件:已经读取了 " + pBytesRead + <br> "/" + pContentLength+ " bytes.");
  32. statusBean.setReadTotalSize(pBytesRead);
  33. statusBean.setCurrentUploadFileNum(pItems);
  34. statusBean.setProcessRunningTime(System.currentTimeMillis());
  35. }
  36. BackGroundService.saveStatusBean(request,statusBean);
  37. }
  38. }<br>
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  243. about: false,
  244. skin: 'notepad',
  245. title: 'php怎么实现数据库验证跳转代码块',
  246. encode: true //是否转义html标签。默认不开启
  247. });
  248. });
  249. </script>