Question

我真的不明白为什么这些简单的东西不起作用。我可以看到，每次设置一个属性时，我都会调用构造函数。问题是当我到达sendInvitation方法时，所有的inviteEmails都是null。

@Named(value = "adminBean")
@RequestScoped
public class AdminBean implements Serializable {

    private String inviteEmail1;
    private String inviteEmail2;
    private String inviteEmail3;
    private BasicUser administrator;
    @EJB
    private MessageBeanRemote messageBean3;

    /** Creates a new instance of AdminBean */
    public AdminBean() {
        HttpSession session = (HttpSession) FacesContext.getCurrentInstance().
                getExternalContext().getSession(true);
        LoginBean loginBean = (LoginBean) session.getAttribute("loginBean");
        administrator = loginBean.getUser();
    }

    public String getInviteEmail1() {
        return inviteEmail1;
    }

    public void setInviteEmail1(String inviteEmail) {
        this.inviteEmail1 = inviteEmail;
    }

    public String getInviteEmail2() {
        return inviteEmail2;
    }

    public void setInviteEmail2(String inviteEmail) {
        this.inviteEmail2 = inviteEmail;
    }

    public String getInviteEmail3() {
        return inviteEmail3;
    }

    public void setInviteEmail3(String inviteEmail) {
        this.inviteEmail3 = inviteEmail;
    }

    public void sendInvitations() { 
    ...
    }
}

使用此bean的页面是另一个页面的一部分：

<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:h="http://java.sun.com/jsf/html"
      xmlns:ui="http://java.sun.com/jsf/facelets">
    <ui:component id="adminComp">
        <h3>Adminstration page</h3>
        <h:form id="inviteForm">
            <h:panelGrid columns="1">
                Invite new members to your group. Type in their emails in the fields below.
                <h:inputText id="email1" value="#{adminBean.inviteEmail1}" size="40"/>
                <h:inputText id="email2" value="#{adminBean.inviteEmail2}" size="40"/>
                <h:inputText id="email3" value="#{adminBean.inviteEmail3}" size="40"/>
                <h:commandButton value="invite" action="#{adminBean.sendInvitations}"/>
            </h:panelGrid>
        </h:form>
    </ui:component>


</html>

adminBean实际上已多次初始化，看起来很奇怪。 “构造函数”是adminBean构造函数，“Get 1”是getInviteEmail1，依此类推。

INFO: START PHASE RESTORE_VIEW 1
INFO: END PHASE RESTORE_VIEW 1
INFO: START PHASE APPLY_REQUEST_VALUES 2
INFO: END PHASE APPLY_REQUEST_VALUES 2
INFO: START PHASE PROCESS_VALIDATIONS 3
INFO: Constructor
INFO: Constructor
INFO: Constructor
INFO: Constructor
INFO: Constructor
INFO: Constructor
INFO: Get 2
INFO: Constructor
INFO: Constructor
INFO: Constructor
INFO: Get 3
INFO: END PHASE PROCESS_VALIDATIONS 3
INFO: START PHASE UPDATE_MODEL_VALUES 4
INFO: Constructor
INFO: Set 1
INFO: Constructor
INFO: Set 2
INFO: Constructor
INFO: Set 3
INFO: END PHASE UPDATE_MODEL_VALUES 4
INFO: START PHASE INVOKE_APPLICATION 5
INFO: Constructor
SEVERE: NullPointerException....
INFO: END PHASE INVOKE_APPLICATION 5
INFO: START PHASE RENDER_RESPONSE 6
INFO: Constructor
INFO: Constructor
INFO: Get 2
INFO: Constructor
INFO: Get 3
INFO: END PHASE RENDER_RESPONSE 6

任何帮助都是适当的。

Answer 1

我不知道@Named在那里做了什么，但每次用值表达式访问bean时都会构造bean是不正常的。它应该在HTTP请求的开头只构造一次。可能@Named背后的配置是错误的。

尝试使用@ManagedBean以JSF方式声明bean，并确保@RequestScoped也来自javax.faces.bean包。

import javax.faces.bean.ManagedBean;
import javax.faces.bean.RequestScoped;

@ManagedBean
@RequestScoped
public class AdminBean implements Serializable {
    // ...
}

除了问题之外，不建议您获取会话范围bean的方法。正常的JSF方式如下：

@ManagedProperty(value="#{loginBean}")
private LoginBean loginBean;

如有必要，请使用以下getter

public BasicUser getAdministrator() {
    return loginBean.getUser();
}

Jsf属性未保存

1 个答案: