效果图如下：
该工程包含五个源文件：BackGroundService.java、BeanControler.java、EventListenerImpl.java、FileUploadListener.java和FileUploadStatus.java；以及2个jsp页面。源码已提供免费
下载，下载后直接部署到tomcat中运行即可。
BackGroundService.java：
[java]
package liuzuochen.sample.upload;
/**
*
*
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 = "index2.
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 = getSt
