使用PrimeFaces fileUpload控件上传文件时出现问题。
问题是上传文件时上传事件被调用了4次。
我找不到明确的理由。
这是我的xhtml页面：
<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:p="http://primefaces.org/ui"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:ui="http://java.sun.com/jsf/facelets">
<h:head>
</h:head>
<h:body>
<ui:composition template="home.xhtml">
<ui:define name="content">
<script type="text/javascript">
function callChangeImage(){
alert('completed');
var hiddenLink = document.getElementById('mainForm:hiddenLink');
hiddenLink.click();
}
function callDeleteImageFromTemp(){
alert('started');
updated = false;
var hiddenLink2 = document.getElementById('mainForm:hiddenLink2');
hiddenLink2.click();
}
</script>
<p>
<p:commandButton value="Agregar Noticia" update="newsTable, display" icon="ui-icon-circle-plus" actionListener="#{newsBean.addNew}" oncomplete="newDialog.show()"/>
<p:commandButton value="Editar Noticia" oncomplete="editNewDialog.show()" icon="ui-icon-pencil"/>
<p:commandButton value ="Eliminar Noticia" icon="ui-icon-trash" onclick="dlgDelete.show()" />
</p>
<p:scrollPanel>
<p:dataTable var="unew" value="#{newsBean.news}" rowKey="#{unew.id}"
selection="#{newsBean.selectedNew}" selectionMode="single" id="newsTable">
<p:ajax event="rowSelect" update=":mainForm:display" />
<f:facet name="header">
Lista de noticias
</f:facet>
<p:column headerText="Numero" sortBy="#{unew.id}" filterBy="#{unew.id}" id="id">
#{unew.id}
</p:column>
<p:column headerText="Titulo" sortBy="#{unew.title}" filterBy="#{unew.title}" id="title">
#{unew.title}
</p:column>
<p:column headerText="Descripcion" sortBy="#{unew.description}" filterBy="#{unew.description}" id="description">
#{unew.description}
</p:column>
<p:column headerText="Enlace" sortBy="#{unew.link}" filterBy="#{unew.link}" id="link">
#{unew.link}
</p:column>
<p:column headerText="Imagen" sortBy="#{unew.img}" filterBy="#{unew.img}" id="img">
#{unew.img}
</p:column>
</p:dataTable>
</p:scrollPanel>
<p:dialog widgetVar="dlgDelete" header="Desea eliminar la noticia #{newsBean.selectedNew.id}?">
<p:panel style="text-align: center">
<p:commandButton value="Si" update="newsTable" action="#{newsBean.removeNew}" oncomplete="dlgDelete.hide()" />
<p:commandButton value="No" onclick="dlgDelete.hide()" type="button" />
</p:panel>
</p:dialog>
<p:dialog header="Editar Noticia" widgetVar="editNewDialog" resizable="false"
showEffect="explode" hideEffect="explode" onHide="">
<p:ajax event="close" listener="#{fileUploadBean.deleteFileFromTemp}" update="messages"/>
<p:ajax event="close" listener="#{newsBean.deleteImageFromTemp}" update="messages"/>
<h:panelGrid id="display" columns="2" cellpadding="4">
<f:facet name="header">
<p>Noticia #{newsBean.selectedNew.id}</p>
<p>
<p:commandLink id="editImage">
<p:graphicImage id="imageNew" value="/temp/#{newsBean.selectedNew.img}" />
</p:commandLink>
<p:overlayPanel id="editImagePanel" for="editImage" hideEffect="fade">
<table cellpadding="5px">
<tr>
<td>
<p:commandButton title="Eliminar Imagen" update="imageNew" actionListener="#{newsBean.removeImage}" icon="ui-icon-trash"/>
</td>
<td>
<p:fileUpload
fileUploadListener="#{fileUploadBean.handleFileUpload}"
mode="advanced"
sizeLimit="1000000"
allowTypes="/(\.|\/)(gif|jpe?g|png)$/"
cancelLabel="Eliminar"
uploadLabel="Subir"
label="Buscar..."
dragDropSupport="false"
oncomplete="callChangeImage();"
onstart="callDeleteImageFromTemp();"
auto="true">
</p:fileUpload>
<p:commandLink id="hiddenLink" action="#{newsBean.changeImage(fileUploadBean.uploadedFile.fileName)}" style="display:none" update="imageNew"/>
<p:commandLink id="hiddenLink2" action="#{newsBean.deleteImageFromTemp}" style="display:none"/>
</td>
</tr>
</table>
</p:overlayPanel>
</p>
</f:facet>
<h:panelGrid id="display2" columns="2" cellpadding="4">
<h:outputText value="Titulo:" />
<p:inputTextarea rows="1" cols="60" value="#{newsBean.selectedNew.title}" id="title"/>
<h:outputText value="Descripcion:" />
<p:inputTextarea rows="6" cols="60" value="#{newsBean.selectedNew.description}" id="description"/>
<h:outputText value="Enlace:" />
<p:inputTextarea rows="1" cols="60" value="#{newsBean.selectedNew.link}" id="link"/>
</h:panelGrid>
<f:facet name="footer">
<p:commandButton value="Guardar" update="newsTable" actionListener="#{newsBean.saveNewEdit}" oncomplete="newDialog.hide()">
<p:ajax listener="#{fileUploadBean.writeUploadedFile('/images/news/', newsBean.selectedNew.id)}" update="messages"/>
</p:commandButton>
</f:facet>
</h:panelGrid>
</p:dialog>
</ui:define>
</ui:composition>
</h:body>
</html>
我的后端豆：
package Beans;
import helpers.Global;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import javax.faces.application.FacesMessage;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.SessionScoped;
import javax.faces.context.FacesContext;
import org.apache.commons.io.FilenameUtils;
import org.primefaces.event.FileUploadEvent;
import org.primefaces.model.UploadedFile;
@ManagedBean
@SessionScoped
public class FileUploadBean {
private UploadedFile uploadedFile;
public FileUploadBean() {
}
public UploadedFile getUploadedFile() {
return uploadedFile;
}
public void setUploadedFile(UploadedFile uploadedFile) {
this.uploadedFile = uploadedFile;
}
public void writeUploadedFile(String path, String fileName){
try
{
if (this.uploadedFile != null)
{
String fileExtension = FilenameUtils.getExtension(this.uploadedFile.getFileName());
path += fileName + "." + fileExtension;
File file = new File(path);
if (file.exists()){
file.delete();
}
file.createNewFile();
InputStream is = uploadedFile.getInputstream();
OutputStream out = new FileOutputStream(file);
byte buf[] = new byte[1024];
int len;
while ((len = is.read(buf)) > 0){
out.write(buf, 0, len);
}
is.close();
out.close();
}else{
}
}catch (Exception ex){
Global.sendErrorsResponseMessage(ex.getMessage());
}
}
public void deleteUploadedFile(String path) {
if (this.uploadedFile != null)
{
path += uploadedFile.getFileName();
File file = new File(path);
if (file.exists()){
file.delete();
}
}
}
public void handleFileUpload(FileUploadEvent event) {
deleteFileFromTemp();
this.uploadedFile = event.getFile();
if (this.uploadedFile == null){
Global.sendErrorsResponseMessage("No se puedo cargar el archivo");
return;
}
try {
saveFileToTemp();
FacesMessage msg = new FacesMessage("Archivo cargado con exito", event.getFile().getFileName());
FacesContext.getCurrentInstance().addMessage(null, msg);
} catch (Exception ex) {
Global.sendErrorsResponseMessage(ex.getMessage());
}
}
public void saveFileToTemp(){
String path = FacesContext.getCurrentInstance().getExternalContext().getRealPath("/");
path = path + "temp" + Global.fileSeparator;
String fileName = FilenameUtils.removeExtension(this.uploadedFile.getFileName());
writeUploadedFile(path, fileName);
}
public void deleteFileFromTemp(){
if (this.uploadedFile != null){
String path = FacesContext.getCurrentInstance().getExternalContext().getRealPath("/");
String imageFileName = this.uploadedFile.getFileName();
path = path + "temp" + Global.fileSeparator + uploadedFile.getFileName();
File f = new File(path);
f.delete();
}
}
}
如果执行此页面并尝试上传文件，则javascript＆＃34;提醒＆＃34;在函数＆＃34; beforeUpload＆＃34;和＆＃34; afterUpload＆＃34;显示4次。
这导致我在使用文件上传更新的图像中闪烁。
我会赞美任何帮助，因为我有点坚持这个。
感谢您的帮助！
此页面的目的是添加新闻（用于个性化新闻阅读器）。 在这个页面中有一个包含新闻的表格，每次选择一个新行时，会出现一个对话框来编辑新的。
在该对话框中，您可以看到New和其他内容的图像。
目标是在编辑器中单击图像时，会出现一个覆盖面板，其中包含上传新图像或删除当前图像的选项。
带有标题＆＃34; Eliminar Imagen＆＃34;的commandButton删除新的图像。 fileUpload为New添加新图像。 所以他们都应该在前端编辑器对话框中更新New的图像。
答案 0 :(得分：-2)
在JSF生命周期中，在以下阶段多次调用动作侦听器：
Apply request values phase; **process events**
Process validations phase; **process events**
Update model values phase; **process events**
Invoke application phase; **process events**