public class ProgressMonitorFileItemFactory extends DiskFileItemFactory {
　private File temporaryDirectory;
　private HttpServletRequest requestRef;
　private long requestLength;
　public ProgressMonitorFileItemFactory(HttpServletRequest request) {
super();
temporaryDirectory = (File)request.getSession().
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getServletContext().getAttribute("javax.servlet.context.tempdir");
requestRef = request;
String contentLength = request.getHeader("content-length");
if(contentLength != null){requestLength
= Long.parseLong(contentLength.trim());}
　}
　public FileItem createItem(String fieldName， 
String contentType，boolean isFormField， String fileName) {
SessionUpdatingProgressObserver observer = null;
if(isFormField == false) //这必须是一文件上传.
　observer = new SessionUpdatingProgressObserver(fieldName，fileName);
　ProgressMonitorFileItem item = new ProgressMonitorFileItem(
　fieldName，contentType，isFormField，
　fileName，2048，temporaryDirectory，
　observer，requestLength);
return item;
　}
　...
　public class SessionUpdatingProgressObserver implements ProgressObserver {
private String fieldName;
private String fileName;
...
public void setProgress(double progress) {
　if(request != null){
request.getSession().setAttribute(
"FileUpload.Progress."+fieldName，progress);
request.getSession().setAttribute(
"FileUpload.FileName."+fieldName，fileName);
　}
}
　}
}

public class ProgressMonitorFileItem extends DiskFileItem {
　private ProgressObserver observer;
　private long passedInFileSize;
　...
　private boolean isFormField;
　...
　@Override
　public OutputStream getOutputStream() throws IOException {
OutputStream baseOutputStream = super.getOutputStream();
if(isFormField == false){
　return new BytesCountingOutputStream(baseOutputStream);
}else{return baseOutputStream;}
　}
　...
　private class BytesCountingOutputStream extends OutputStream{
private long previousProgressUpdate;
private OutputStream base;
public BytesCountingOutputStream(OutputStream ous){ base = ous; }
...
private void fireProgressEvent(int b){
　bytesRead += b;
　...
　double progress = (((double)(bytesRead)) / passedInFileSize);
　progress *= 100.0
　observer.setProgress();
}
　}
}

＜comp:fileUpload
　value="#{uploadPageBean.uploadedFile}"
　uploadIcon="images/upload.png"
　styleClass="progressBarDiv"
　progressBarStyleClass="progressBar"
　cellStyleClass="progressBarCell"
　activeStyleClass="progressBarActiveCell"＞
＜%--下面是一旦文件上传完成将成为可见的组件--%＞
＜h:panelGrid columns="2" cellpadding="2" cellspacing="0" width="100%"＞
＜f:facet name="header"＞
＜h:outputText styleClass="text"
value="文件上传成功." /＞
＜/f:facet＞
＜h:panelGroup ＞
＜h:commandButton action="#{uploadPageBean.reset}"
image="images/reset.png"/＞
＜/h:panelGroup＞
＜h:panelGroup ＞
＜h:commandButton action="#{uploadPageBean.nextPage}"
image="images/continue.png"/＞
＜/h:panelGroup＞
＜/h:panelGrid＞
＜/comp:fileUpload＞
　文件上传组件的value属性需要用一个拥有一个FileItem的属性绑定到一个bean上。组件只有在该文件被服务器成功收到时才显示。