AJAX+JSF组件实现高性能的文件上载［转］

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 style="text-align:left;display:block;width:100%;"＞

＜h:commandButton action="#{uploadPageBean.reset}"

image="images/reset.png"/＞

＜/h:panelGroup＞

＜h:panelGroup style="text-align:right;display:block;width:100%;"＞

＜h:commandButton action="#{uploadPageBean.nextPage}"

image="images/continue.png"/＞

＜/h:panelGroup＞

＜/h:panelGrid＞

＜/comp:fileUpload＞
　

public void decode(FacesContext context， UIComponent component) {

　UIFileUpload input = (UIFileUpload) component;

　//检查是否这是一个上传进度请求，或是一个实际的上传请求.

　ExternalContext extContext = context.getExternalContext();

　Map parameterMap = extContext.getRequestParameterMap();

　String clientId = input.getClientId(context);

　Map requestMap = extContext.getRequestParameterMap();

　if(requestMap.get(clientId) == null){

return;//什么也不做，返回

　}

　if(parameterMap.containsKey(PROGRESS_REQUEST_PARAM_NAME)){

//这是一个在该文件请求中的得到进度信息的请求.

//得到该进度信息并把它生成为XML

HttpServletResponse response = 
(HttpServletResponse)context.getExternalContext().getResponse();

//设置响应的头信息

response.setContentType("text/xml");

response.setHeader("Cache-Control"， "no-cache");

try {

　ResponseWriter writer = FacesUtils.setupResponseWriter(context);

　writer.startElement("progress"， input);

　writer.startElement("percentage"， input);

　//从会话中获得当前进度百分数(由过滤器所设置).

　Double progressCount = (Double)extContext.getSessionMap().

　get("FileUpload.Progress." +input.getClientId(context)); 

　if(progressCount != null){

writer.writeText(progressCount， null);

　}else{

writer.writeText("1"， null);//我们还没有收到上传

　}

　writer.endElement("percentage");

　writer.startElement("clientId"， input);

　writer.writeText(input.getClientId(context)， null);

　writer.endElement("clientId");

　writer.endElement("progress");

} catch(Exception e){

　//做一些错误记录...

}

}else{

　//正常的译码请求.

...

//正常的译码请求.

if(requestMap.get(clientId).toString().equals("file")){

try{

　HttpServletRequest request = (HttpServletRequest)extContext.getRequest();

　FileItem fileData = (FileItem)request.getAttribute(clientId);

　if(fileData != null) input.setSubmittedValue(fileData);

　//现在我们需要清除与该项相关的任何进度

　extContext.getSessionMap().put(
"FileUpload.Progress." + input.getClientId(context)，new Double(100));

}catch(Exception e){

　throw new RuntimeException("不能处理文件上传" +" - 请配置过滤器."，e); 

}

}

function refreshProgress(){ 

　// 假定我们正在进入到阶段2.

　document.getElementById('fileUpload1_stage1').style.display = 'none';

　document.getElementById('fileUpload1_stage2').style.display = '';

　document.getElementById('fileUpload1_stage3').style.display = 'none';

　//创建AJAX寄送

　AjaxRequest.post( 

　{

//指定正确的参数，以便

//该组件在服务器端被正确处理 

'parameters':{ 'uploadForm':'uploadForm'，

'fileUpload1':'fileUpload1'，

'jsf.component.UIFileUpload':'1'，

'ajax.abortPhase':'4' } //Abort at Phase 4.

//指定成功处理相应的回调方法.

，'onSuccess':function(req) { 

var xml = req.responseXML;

if( xml.getElementsByTagName('clientId').length == 0) { 

　setTimeout('refreshProgress()'，200); return;

} 

var clientId = xml.getElementsByTagName('clientId');

clientId = clientId[0].firstChild.nodeValue + '_progressBar';

//从XML获取百分比

var percentage = 
xml.getElementsByTagName('percentage')[0].firstChild.nodeValue;

var innerSpans =
document.getElementById(clientId).getElementsByTagName('span');

document.getElementById(clientId + 'label').innerHTML
= Math.round(percentage) + '%';

//基于当前进度，设置这些span的式样类。

for(var i=0;i＜innerSpans.length;i++){

　if(i ＜ percentage){

innerSpans[i].className = 'active';

　}else{

innerSpans[i].className = 'passive'; 

　}

}

//如果进度不是100，我们需要继续查询服务器以实现更新.

if(percentage != 100){ 

　setTimeout('refreshProgress()'，400);

} else { 

　//文件上传已经完成，我们现在需要把该组件送入到第3个阶段.

　document.getElementById('fileUpload1_stage1').style.display = 'none';

　document.getElementById('fileUpload1_stage2').style.display = 'none'; 

　document.getElementById('fileUpload1_stage3').style.display = '';

} 

　}

});

}

return builder.toString();