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我正在尝试在用户登录我的应用程序后加载一些数据。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包含用于登录用户的代码的支持 bean，然后我有一个ViewScoped特定于页面的支持 bean（它注入 SessionScoped bean）来加载页面的数据。

loadData()目前这是我拥有的代码，加载数据时我得到一个空指针，因为调用该方法时用户名不存在。

我很难想出一个解决这个问题的方法，因为我不想把登录对话框放在每个页面上，如果可能的话，把它保存在 template.xhtml 文件中。

模板.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>
...

用户组.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  
        }
    }
}

用户组支持

@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.
    }
}
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1 回答 1

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我已经通过使用找到了一个很好的解决方案ui:param。基本上我ui:param在我的页面特定的 xhtml 中设置了我的支持 bean 值，然后ui:param在我的模板中引用它。

使用新解决方案更新了问题中的代码：

模板.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>
...

用户组.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  
        }
    }
}

用户组支持

@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());  
    }
}
于 2013-10-17T16:01:22.390 回答