AJAX+JSP实现基于WEB的文件上传的进度控制(2)

2.1.3. 后台服务类（BackGroundService）

　　 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:[e-mail]
 */
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);
             }
         }
     }
}

   2.1.4. 文件上传状态控制类（BeanControler）

　　 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:[e-mail]
 */

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);
     }
}

2.2. 客户端代码

　　 客户端我们采用Prototype框架。请下载。

   2.2.1. AjaxWrapper.js

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

   2.2.2. fileUpload.html

　　 fileUpload.html是文件上传界面。 请下载。

   2.2.3. result.jsp

　　 result.jsp是文件上传结果显示界面。 请下载

   2.2.4. fileUpload.css

　　 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;
}

2.3. 配置文件

　　 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>

3. 结语

　　 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。

评论

1 楼 mogui258 2010-08-22  

没看见源码啊？
怎么下载？