为什么“受管Bean列表”在sessionscoped中变得包含空元素？

Question

I want to get some information about contacts and display them in a table. 我想获取有关联系人的一些信息并将其显示在表格中。 I used two managed beans named by PersonalContact and BusinessContact and one abstract class named by Contact including firstName , lastName , ID , email and mphone attributes which derives from.Also, one generic class to add beans to an arraylist. 我使用了两个由PersonalContact和BusinessContact命名的托管bean和一个由Contact命名的抽象类，其中包括mphone派生的firstName ， lastName ， ID ， email和mphone属性。还有一个通用类将bean添加到数组列表中。 I put here just BusinessContact as a bean, business as XHTML and tableBusiness as a table and generic class AddressBook , files of personal is parallel of them. 我在这里仅将BusinessContact作为一个bean，将Business作为XHTML和tableBusiness作为一个表以及泛型类AddressBook ，personal文件与它们平行。

Inputs getting from screen are assigned to attributes of beans but when the beans go to Arraylist to be added, its content becomes null. 从屏幕获取的输入被分配给bean的属性，但是当bean进入要添加的Arraylist ，其内容将为空。 Why is that? 这是为什么？ Is that about scopes? 那是关于范围的吗？

Here is my bean: 这是我的豆子：

import javax.faces.bean.ManagedBean;
import javax.faces.bean.ViewScoped;

@ManagedBean
@ViewScoped
public class BusinessContact extends Contact{
    private String companyName,workPhone;

    public BusinessContact() {}

    public BusinessContact(String companyName, String workPhone, String ID, String firstName, String lastName, String email, String mphone) {
        super(ID, firstName, lastName, email, mphone);
        this.companyName = companyName;
        this.workPhone = workPhone;
    }


    /**
     * Creates a new instance of BusinessContact
     */
    public String getCompanyName() {
        return companyName;
    }

    public void setCompanyName(String companyName) {
        this.companyName = companyName;
    }

    public String getWorkPhone() {
        return workPhone;
    }

    public void setWorkPhone(String workPhone) {
        this.workPhone = workPhone;
    }        
}

Here is my business.xhtml: 这是我的business.xhtml：

<?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://xmlns.jcp.org/jsf/html"
  xmlns:f="http://xmlns.jcp.org/jsf/core"
  xmlns:ui="http://xmlns.jcp.org/jsf/facelets">
 <h:head>
    <title>Contact</title>
 </h:head>
 <h:body>
    <h:form>
    <h:panelGrid columns="2"> 
     First Name:
     <h:inputText id="firstName" required="true" 
                  requiredMessage="Can not be blank" value="#{businessContact.firstName}">
     </h:inputText>
     ID:
     <h:inputText id="id" required="true" 
                  requiredMessage="Can not be blank" value="#{businessContact.ID}">
     </h:inputText>
     Last Name:
     <h:inputText id="lastName" required="true" 
                  requiredMessage="Can not be blank" value="#{businessContact.lastName}">
     </h:inputText>

     E-mail:
     <h:inputText id="email" required="true" 
                  requiredMessage="Can not be blank" value="#{businessContact.email}">
     </h:inputText>
     Mobile Phone:
     <h:inputText id="mphone" required="true" 
                  requiredMessage="Can not be blank" value="#{businessContact.mphone}">
     </h:inputText>
     Company Name:
     <h:inputText id="companyName" required="true" 
                  requiredMessage="Can not be blank" value="#{businessContact.companyName}">
     </h:inputText>
     Work Phone:
     <h:inputText id="workPhone" required="true" 
                  requiredMessage="Can not be blank" value="#{businessContact.workPhone}">
     </h:inputText>

    </h:panelGrid>

    <h:commandButton  value="Add" id="add" action="#{addressBook.add(BusinessContact)}"></h:commandButton>

    <h:commandButton  value="Delete" id="delete" action="#{addressBook.remove(BusinessContact)}"></h:commandButton>
    <h:outputLink id="t" value="tableBusiness.xhtml"> Click see the table</h:outputLink>
    <ui:debug hotkey="k" rendered="true"/>
  </h:form>
</h:body>

This is my generic class for putting beans to an arraylist: 这是用于将bean放入arraylist的通用类：

import java.util.ArrayList;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.SessionScoped;

@ManagedBean
@SessionScoped
public class AddressBook <T extends Contact> {
    private ArrayList<T> list = new ArrayList<T>();
    T clas;

    public ArrayList<T> getList() {
        return list;
    }

    public void setList(ArrayList<T> list) {
        this.list = list;
    }

    public void add(T obj) { 
        this.clas=obj;
        //System.out.println(obj.getFirstName()+" ");
        list.add(obj);

    }
    public void remove(T obj)
    {
       list.remove(obj);
    }
    /**
     * Creates a new instance of AddressBook
     */
    public AddressBook() {}        
}

And lastly, this xhmtl for displaying arraylist in table: 最后，此xhmtl用于在表中显示arraylist：

<html xmlns="http://www.w3.org/1999/xhtml"
  xmlns:h="http://xmlns.jcp.org/jsf/html"
  xmlns:f="http://xmlns.jcp.org/jsf/core">
<h:head>

</h:head>
<h:body>
    <h:form>
        "#{businessContact.firstName}"
       <h:dataTable value="#{addressBook.list}" var="BusinessContact">
        <h:column>
                <f:facet name="header">
                    First Name
                </f:facet>
            <h:outputText value="#{businessContact.firstName}">
            </h:outputText>
        </h:column>
            <h:column>
                <f:facet name="header">
                    Last Name
                </f:facet>
                #{businessContact.lastName}
            </h:column>
            <h:column>
                <f:facet name="header">
                  Mobile Phone
                </f:facet>
                #{businessContact.mphone}
            </h:column> 
            <h:column>
                <f:facet name="header">
                  E-mail
                </f:facet>
                #{businessContact.email}
            </h:column>  
            <h:column>
                <f:facet name="header">
                  Company Name
                </f:facet>
                #{businessContact.companyName}
            </h:column>  
            <h:column>
                <f:facet name="header">
                  Work Phone
                </f:facet>
                #{businessContact.workPhone}
            </h:column>  
      </h:dataTable>
    </h:form>
</h:body>
</html>

Answer 1

You are naming the var="BusinessContact" but trying to use it as "businessContact" 您正在命名var="BusinessContact"但尝试将其用作"businessContact"

Change this line 更改此行

<h:dataTable value="#{addressBook.list}" var="BusinessContact">

to this 对此

<h:dataTable value="#{addressBook.list}" var="businessContact">

为什么“受管Bean列表”在sessionscoped中变得包含空元素？

问题描述

1 个解决方案

解决方案1
1 2014-12-06 09:01:44

为什么“受管Bean列表”在sessionscoped中变得包含空元素？

问题描述

1 个解决方案

解决方案1 1 2014-12-06 09:01:44

解决方案1
1 2014-12-06 09:01:44