AJAX+JSF组件实现高性能的文件上载(2)

public class ProgressMonitorFileItemFactory extends DiskFileItemFactory {　private File temporaryDirectory;　private HttpServletRequest requestRef;　private long requestLength;　public ProgressMonitorFileItemFactory(HttpServletRequest request) {super();temporaryDirectory = (File)request.getSession().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。