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

　　 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);
      }
    }
  }
}

　　 这是一个单例类，它的功能是为客户端保存文件上传状态，这里我没有使用Session来存储文件上传状态，因为对于AJAX这种异步调用，服务器会开启不同的Session，所以无法通过Session保存文件上传状态。 我并不认为这种方法最好，如果有更好的方法，欢迎大家一起讨论。 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: 类控制器
 *
 * Description: 主要作用是对FileUploadStatus进行管理，为客户端提供相应的
 * FileUploadStatus类对象。这是一个单例类。
 *
 */
import java.util.Vector;
public class BeanControler {
  private static BeanControler beanControler = new BeanControler();
  private Vector vector = new Vector();
  private BeanControler() {
  }
  public static BeanControler getInstance() {
    return beanControler;
  }
  /**
   * 取得相应FileUploadStatus类对象的存储位置
   */
  private int indexOf(String strID) {
    int nReturn = -1;
    for (int i = 0; i < vector.size(); i++) {
      FileUploadStatus status = (FileUploadStatus) vector.elementAt(i);
      if (status.getUploadAddr().equals(strID)) {
        nReturn = i;
        break;
      }
    }
    return nReturn;
  }
  /**
   * 取得相应FileUploadStatus类对象
   */
  public FileUploadStatus getUploadStatus(String strID) {
    return (FileUploadStatus) vector.elementAt(indexOf(strID));
  }
  /**
   * 存储FileUploadStatus类对象
   */
  public void setUploadStatus(FileUploadStatus status) {
    int nIndex = indexOf(status.getUploadAddr());
    if ( -1 == nIndex) {
      vector.add(status);
    } else {
      vector.insertElementAt(status, nIndex);
      vector.removeElementAt(nIndex + 1);
    }
  }
  /**
   * 删除FileUploadStatus类对象
   */
  public void removeUploadStatus(String strID){
    int nIndex = indexOf(strID);
    if(-1!=nIndex)
      vector.removeElementAt(nIndex);
  }
}

　　 客户端我们采用Prototype框架。请下载。

　　 AjaxWrapper.js对Prototype进行了封装。请下载分析

　　 fileUpload.html是文件上传界面。 请下载。

　　 result.jsp是文件上传结果显示界面。 请下载

　　 fileUpload.css是样式文件。 源代码如下：

body {
  color:#000;
  background-color:white;
  font:15px Georgia, "Lucida Grande", Arial, sans-serif;
  letter-spacing:0.01em;
  margin:15px;
}
#controlPanel,#resultPanel{
  width:700px;
  margin:20px auto;
  padding:25px;
  border:3px solid gray;
  -moz-border-radius:10px;
  background:#f8f8f8;
}
#errorArea{
   width:400px;
  margin:20px auto;
  padding:25px;
  border:3px solid gray;
  -moz-border-radius:10px;
  background:red;
}
#normalMessageArea{
  width:400px;
  margin:20px auto;
  padding:25px;
  border:3px solid gray;
  -moz-border-radius:10px;
  background:yellow;
}
#progressBar { padding-top: 5px; }
  #totalProgressBarBox {
   width: 350px;
   height: 20px;
   border: 1px inset;
   background: #eee;
}
#totalProgressBarBoxContent {
  width: 0;
  height: 20px;
  border-right: 1px solid #444;
  background: #9ACB34;
}

　　 web.xml中完成Servlet的配置。

<?xml version="1.0" encoding="UTF-8"?>
<web-app id="WebApp_ID" version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
<display-name>AjaxPractice</display-name>
<servlet>
  <description></description>
  <display-name>BackGroundService</display-name>
  <servlet-name>BackGroundService</servlet-name>
  <servlet-class>liuzuochen.sample.upload.BackGroundService</servlet-class>
</servlet>

<servlet-mapping>
  <servlet-name>BackGroundService</servlet-name>
  <url-pattern>*.action</url-pattern>
</servlet-mapping>
<welcome-file-list>
  <welcome-file>index.html</welcome-file>
   <welcome-file>index.htm</welcome-file>
  <welcome-file>index.jsp</welcome-file>
  <welcome-file>default.html</welcome-file>
  <welcome-file>default.htm</welcome-file>
  <welcome-file>default.jsp</welcome-file>
</welcome-file-list>
</web-app>

　　 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。