primefaces的删除功能出现的问题

前端页面
  <p:dataTable id="patchfiledatatable" var="patch" value="#{patchBean.files}" dynamic="true" emptyMessage=""  paginator="true" rows="10" paginatorPosition="top">
     <p:column >
<f:facet name="header"> 
            <h:outputText value="删除" /> 
       </f:facet>
        <p:growl id="deleMeaage-dialog" showSummary="true" howDetail="true"/>
<p:commandLink id="delLink"  action="#{patchBean.deletePatch}" update=":patchForm"> 
<f:setPropertyActionListener value="#{patch.path}" target="#{patchBean.delFilePath}" />
<h:outputText value="删除" />
</p:commandLink>
    </p:column>
</p:dataTable>

后台代码
@ManagedBean(name = "patchBean")
@SessionScoped
public class TreeBean{
     private List<PatchOutFile> files;
     private String delFilePath;
public List<PatchOutFile> getFiles() {
return files;
}
public void setFiles(List<PatchOutFile> files) {
this.files = files;
}
        public String getDelFilePath() {
return delFilePath;
}
public void setDelFilePath(String delFilePath) {
this.delFilePath = delFilePath;
}
//取得files内容（省略）
//删除不定文件
public void deletePatch(){
File delFile = new File(delFilePath);
FacesMessage msg = null;
try {
if(delFile.exists()){
boolean flag = delFile.delete();
System.out.println(flag);
if(flag){
files.clear();
this.getSubFiles(delFile.getParent());
msg = new FacesMessage(FacesMessage.SEVERITY_INFO, "删除成功", null);
}
}else{
msg = new FacesMessage(FacesMessage.SEVERITY_INFO, "该文件不存在", null);
}
FacesContext.getCurrentInstance().addMessage("patchForm:deleMeaage-dialog", msg);
} catch (Exception e) {
System.out.println("删除出现异常");
msg = new FacesMessage(FacesMessage.SEVERITY_ERROR, "操作失败", null);
FacesContext.getCurrentInstance().addMessage("patchForm:deleMeaage-dialog", msg);
e.printStackTrace();
}
}
}