This is a simple example of use these article :

public FileUploadForm() { 
 if(FacesContext.getCurrentInstance().getExternalContext().
 getRequestParameterMap().containsKey("defaultsavepath_name"))
{ 
 this.savePathName=FacesContext.getCurrentInstance().
 getExternalContext().getRequestParameterMap().
 get("defaultsavepath_name").toString();

 FacesContext.getCurrentInstance().getExternalContext().
 getRequestParameterMap().put("defaultsavepath_name",this.savePathName);
}
else
{
 Object tmpDir =
FacesContext.getCurrentInstance().
 getExternalContext().getRequestParameterMap().get("dirName");
 if (tmpDir != null && !tmpDir.toString().equals(""))
 {
 String tmpdirName = tmpDir.toString();
 savePathName = savePathName + "\\" + tmpdirName;
 FacesContext.getCurrentInstance().getExternalContext().
 getRequestParameterMap().
 put("defaultsavepath_name", this.savePathName);
}
...
}