JSF - 应用程序设计问题。在用户登录到支持bean B之后，如何在辅助bean A中获取数据

时间：2013-10-16 21:58:53

标签： java jsf jsf-2

我正在尝试在用户登录我的应用后加载一些数据。我需要用户名来加载特定于用户的数据。我遇到的问题是我有一个SessionScoped支持bean，其中包含用于登录用户的代码，然后我有一个ViewScoped页面特定的支持bean（它注入了SessionScoped bean）是加载页面的数据。

目前这是我的代码，我在加载数据时得到一个空指针，因为调用loadData()方法时用户名不存在。

我很难找到解决这个问题的方法，因为我不想在每个页面上放置登录对话框，如果可能的话，将其保存在template.xhtml文件中。

的template.xhtml 

...
<!-- Login Dialog -->
    <p:dialog id="loginDialog" header="Login" widgetVar="loginWidget" modal="true" visible="#{!accessBacking.hasAccess}" closable="false">
        <h:form id="loginForm">
            <p:messages id="loginFormMessages" severity="error" autoUpdate="true" showDetail="true" />
            <h:panelGrid columns="2" cellspacing="10" width="300">  

            <p:outputLabel for="username" value="Username" />  
            <p:inputText id="username" value="#{accessBacking.username}" required="true" requiredMessage="Username is Required" />

            <p:outputLabel for="password" value="Password" />  
            <p:password id="password" value="#{accessBacking.password}" required="true" requiredMessage="Password is Required" />

            <h:panelGroup></h:panelGroup>
                <h:panelGroup>
                    <p:commandButton value="Login" styleClass="ui-priority-primary" actionListener="#{accessBacking.checkViewAccess}" oncomplete="handleAuthenticationRequest(xhr, status, args)" update="loginFormMessages" />
                </h:panelGroup>
            </h:panelGrid> 
        </h:form>
    </p:dialog>
...

userGroups.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://java.sun.com/jsf/html" 
      xmlns:f="http://java.sun.com/jsf/core"
      xmlns:ui="http://java.sun.com/jsf/facelets" 
      xmlns:p="http://primefaces.org/ui">

<h:body>

    <f:metadata>
        <f:event type="preRenderView" listener="#{userGroupBacking.setCurrentMenu}" />
    </f:metadata>

    <ui:composition template="/templates/template.xhtml">
        <p:dataTable var="user" value="#{userGroupBacking.users}" editable="true" id="userTable">
...

AccessBacking.java 

@ManagedBean(name="accessBacking")
@SessionScoped
public class AccessBacking {
        private String username;
    private String password;

    public boolean checkViewAccess() {
        Access access = new Access();
        if(access.authenticate(username, password)) {
          // user is logged in  
        }
    }
}

UserGroupBacking 

@ManagedBean(name="userGroupBacking")
@ViewScoped
public class UserGroupBacking {

        @ManagedProperty(value="#{accessBacking}")
    private AccessBacking accessBacking;
    public void setAccessBacking(AccessBacking accessBacking) {
        this.accessBacking = accessBacking;
    }

        @PostConstruct
    public void init() {
        loadData();
    }

        /**
     * Loads the data for the page
     */
    public void loadData() {
        Dao dao = new Dao(ds);
        users = dao.findAllUsers(accessBacking.getUsername(), accessBacking.getRoles());  // NULL POINTER BECAUSE ACCESSBACKING.GETUSERNAME() IS NULL SINCE THE USER HASN'T LOGGED IN YET.
    }
}

1 个答案:

答案 0 :(得分：0)

我使用ui:param找到了一个好的解决方案。基本上我在我的页面特定的xhtml中设置了ui:param我的支持bean值，然后在我的模板中引用ui:param。

使用新解决方案更新了问题代码：

的template.xhtml 

...
<!-- NOTE the 'myBacking' instead of the 'userGroupBacking' -->
<!-- Login Dialog -->
    <p:dialog id="loginDialog" header="Login" widgetVar="loginWidget" modal="true" visible="#{!myBacking.hasAccess}" closable="false">
        <h:form id="loginForm">
            <p:messages id="loginFormMessages" severity="error" autoUpdate="true" showDetail="true" />
            <h:panelGrid columns="2" cellspacing="10" width="300">  

            <p:outputLabel for="username" value="Username" />  
            <p:inputText id="username" value="#{accessBacking.username}" required="true" requiredMessage="Username is Required" />

            <p:outputLabel for="password" value="Password" />  
            <p:password id="password" value="#{accessBacking.password}" required="true" requiredMessage="Password is Required" />

            <h:panelGroup></h:panelGroup>
                <h:panelGroup>
                    <p:commandButton value="Login" styleClass="ui-priority-primary" actionListener="#{myBacking.checkViewAccess}" oncomplete="handleAuthenticationRequest(xhr, status, args)" update="loginFormMessages" />
                </h:panelGroup>
            </h:panelGrid> 
        </h:form>
    </p:dialog>
...

userGroups.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://java.sun.com/jsf/html" 
      xmlns:f="http://java.sun.com/jsf/core"
      xmlns:ui="http://java.sun.com/jsf/facelets" 
      xmlns:p="http://primefaces.org/ui">

<h:body>

    <f:metadata>
        <f:event type="preRenderView" listener="#{userGroupBacking.setCurrentMenu}" />
    </f:metadata>

    <!-- THIS IS PART OF THE SOLUTION -->
    <ui:param name="myBacking" value="#{userGroupBacking}" />

    <ui:composition template="/templates/template.xhtml">
        <p:dataTable var="user" value="#{userGroupBacking.users}" editable="true" id="userTable">
...

AccessBacking.java 

@ManagedBean(name="accessBacking")
@SessionScoped
public class AccessBacking {
    private String username;
    private String password;

    public boolean checkViewAccess() {
        Access access = new Access();
        if(access.authenticate(username, password)) {
          // user is logged in  
        }
    }
}

UserGroupBacking 

@ManagedBean(name="userGroupBacking")
@ViewScoped
public class UserGroupBacking {

    @ManagedProperty(value="#{accessBacking}")
    private AccessBacking accessBacking;
    public void setAccessBacking(AccessBacking accessBacking) {
        this.accessBacking = accessBacking;
    }

    @PostConstruct
    public void init() {
        loadData();
    }

    // CHECKS AGAINST ACCESSBACKING
    public boolean isHasAccess() {
    return accessBacking.isHasAccess();
    }

    // CHECKS AGAINST ACCESSBACKING
    public boolean checkViewAccess() {
    return accessBacking.checkViewAccess();
    }

    /**
     * Loads the data for the page
     */
    public void loadData() {
        Dao dao = new Dao(ds);
        users = dao.findAllUsers(accessBacking.getUsername(), accessBacking.getRoles());  
    }
}
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