通过托管bean将值从一个jsf页面传递到另一个页面

Question

我需要通过托管bean（bean.java）将值（studentId）从jsf视图（list.xhtml）传递到另一个jsf页面（editor.xhtml）。我可以在bean页面中获取值，但我无法访问编辑器中的值。你能告诉我出了什么问题吗？ 希望听到一些建议

list.xhtml

    <h:dataTable  value="#{student.createList()}" var="student" styleClass="studentTable"
                         columnClasses=",,,fixedWidth" border="1" cellspacing="2" cellpadding="2">
                <h:column>
                    <f:facet name="header">Student ID</f:facet>
                    <h:outputText value="#{student.studentId}"></h:outputText>
                </h:column>
           <h:column>
                <f:facet name="header">Name</f:facet>
                <h:outputText value="#{student.fname}"></h:outputText>
            </h:column>

                <h:column>
                    <f:facet name="header">Surname</f:facet>
                    <h:outputText value="#{student.lname}"></h:outputText>
                </h:column>
  <h:commandLink  actionListener="#{student.edit()}" value ="Editt">
                             <f:param name="id" value="#{student.studentId}"/>

                         </h:commandLink>

editor.xhtml

<h:panelGrid border="" cellpadding="20" cellspacing="20" columns="3">
                        <h:outputLabel value="Student Id" />
                        <h:inputText value="#{student.studentId}" readonly="true" required="true" requiredMessage="Id is Required" id="Eid">
                        </h:inputText> <h:message for="Eid"/>

                        <h:outputLabel value="Student Name" />
                        <h:inputText value="#{student.fname}" required="true" requiredMessage="Name is Required" id="Ename">

                        </h:inputText> <h:message for="Ename"/>
                        <h:outputLabel value="Student Age" />
                            <h:inputText value="#{student.lname}" required="true" requiredMessage="age is Required" id="Eage">

 <h:commandLink value="Update" action="userRecords" actionListener="#{student.update()}">

                        </h:commandLink>

student.java

public void edit(){
     System.out.println("called from edit()"+ this.StudentId);

        List<Student> arrList = createList();
         FacesContext fc = FacesContext.getCurrentInstance();
mapParam=fc.getExternalContext().getInitParameterMap();

        String idStudent;
        HttpServletRequest request = (HttpServletRequest) fc.getExternalContext().getRequest();


        for (Student studentManagedBean : arrList) {
            if (studentManagedBean.getStudentId() == idStudent) {
                this.setStudentId(studentManagedBean.getStudentId());//Error
                this.setFname(studentManagedBean.getFname());
                this.setLname(studentManagedBean.getLname());

            }
System.out.println(" we have "+ this.getStudentId() + this.getFname() );
        }


 }

 public void update() {
         Connection conn=null;
      try{

           Class.forName("org.apache.derby.jdbc.ClientDriver");
         conn = DriverManager.getConnection("jdbc:derby://localhost:1527/XX","XX","XXX");
      }catch(Exception e){

      }
       String str = "Update student set FNAME=?,LNAME=? where STUDENTID=?";
        FacesContext fc = FacesContext.getCurrentInstance();
        HttpServletRequest request = (HttpServletRequest) fc.getExternalContext().getRequest();
         int  idStudent = Integer.parseInt(request.getParameter("id"));
        try {

           PreparedStatement pstmt = conn.prepareStatement(str);
            pstmt.setString(1, this.getFname());
            pstmt.setString(2, this.getLname());
            pstmt.setInt(3, idStudent);
//            System.out.println("Id Student Update :" + idStudent);//Error
            int executeUpdate = pstmt.executeUpdate();
            if (executeUpdate > 0) {
                System.out.println("Update SuccessFully");

            }
        } catch (SQLException ex) {
            Logger.getLogger(Student.class.getName()).log(Level.SEVERE, null, ex);
        } finally {

        }