java - JSF 2.0 问题

Question

我正在做一个使用 JSF 2.0 和 Primefaces UI 组件的项目。

有一个带有选项卡的选项卡 View 组件，“天”，“周”和“月”。在所有选项卡中，我必须在每个选项卡中显示条形图。同样，我使用以下三种方法获取三个列表。在以下代码中，UpdateCountHelper 正在从数据库中获取数据。因此，UpdateCountHelper 需要一些时间来获取数据。

这是获取列表的代码:

public List<UpdateCount> getDayUpdateCounts() {
        if (projectFlag == true) {
            if (displayFlag == 1) {
                dayUpdateCounts = UpdateCountHelper.getProjectUpdates(1);
            } else {
                dayUpdateCounts = UpdateCountHelper.getProjectUpdates(name, 1);
            }
        } else {
            dayUpdateCounts = UpdateCountHelper.getResourceUpdates(userName, 1);
        }

        return dayUpdateCounts;
    }

    public List<UpdateCount> getMonthUpdateCounts() {
        if (projectFlag == true) {
            if (displayFlag == 1) {
                monthUpdateCounts = UpdateCountHelper.getProjectUpdates(30);
            } else {
                monthUpdateCounts = UpdateCountHelper.getProjectUpdates(name, 30);
            }
        } else {
            monthUpdateCounts = UpdateCountHelper.getResourceUpdates(userName, 30);
        }

        return monthUpdateCounts;
    }

    public List<UpdateCount> getWeekUpdateCounts() {
        if (projectFlag == true) {

            if (displayFlag == 1) {
                weekUpdateCounts = UpdateCountHelper.getProjectUpdates(7);
            } else {
                weekUpdateCounts = UpdateCountHelper.getProjectUpdates(name, 7);
            }
        } else {
            weekUpdateCounts = UpdateCountHelper.getResourceUpdates(userName, 7);
        }

        return weekUpdateCounts;
    }

这是条形图 UI 的代码:

<p:panel id="Chart">
                <p:tabView dynamic="false" cache="false">
                    <p:tab title="Day">
                        <p:panel id="chartDayPanel">
                            <center>
                                <h:outputText id="projectWiseDayText" rendered="#{systemUtilizationServiceBean.projectFlag}" value="Project Wise Day Update"/>
                                <p:columnChart id="projectWiseDayUpdateChart" rendered="#{systemUtilizationServiceBean.projectFlag}" value="#{systemUtilizationServiceBean.dayUpdateCounts}" var="dayWiseUpdate" xfield="#{dayWiseUpdate.name}" height="200px" width="640px">
                                    <p:chartSeries label="Project Wise Current Day Update" value="#{dayWiseUpdate.noUpdates}"/>
                                </p:columnChart>
                                <h:outputText id="resourceWiseDayText" rendered="#{systemUtilizationServiceBean.resourceFlag}" value="Resource Wise Day Update"/>
                                <p:columnChart id="resourceWiseDayUpdateChart" rendered="#{systemUtilizationServiceBean.resourceFlag}" value="#{systemUtilizationServiceBean.dayUpdateCounts}" var="dayWiseResourceUpdate" xfield="#{dayWiseResourceUpdate.name}" height="200px" width="640px">
                                    <p:chartSeries label="Resource Wise Current Day Update" value="#{dayWiseResourceUpdate.noUpdates}"/>
                                </p:columnChart>
                            </center>
</p:panel>
                    </p:tab>
                    <p:tab title="Week">
                        <p:panel id="chartWeekPanel">
                            <center>
                                <h:outputText id="projectWiseWeekText" rendered="#{systemUtilizationServiceBean.projectFlag}" value="Project Wise Week Update"/>
                                <p:columnChart id="projectWiseWeekUpdateChart" rendered="#{systemUtilizationServiceBean.projectFlag}" value="#{systemUtilizationServiceBean.weekUpdateCounts}" var="weekWiseUpdate" xfield="#{weekWiseUpdate.name}" height="200px" width="640px">
                                    <p:chartSeries label="Project Wise Current Week Update" value="#{weekWiseUpdate.noUpdates}"/>
                                </p:columnChart>
                                <h:outputText id="resourceWiseWeekText" rendered="#{systemUtilizationServiceBean.resourceFlag}" value="Resource Wise Week Update"/>
                                <p:columnChart id="resourceWiseWeekUpdateChart" rendered="#{systemUtilizationServiceBean.resourceFlag}" value="#{systemUtilizationServiceBean.weekUpdateCounts}" var="weekWiseResourceUpdate" xfield="#{weekWiseResourceUpdate.name}" height="200px" width="640px">
                                    <p:chartSeries label="Resource Wise Current Week Update" value="#{weekWiseResourceUpdate.noUpdates}"/>
                                </p:columnChart>
                            </center>
</p:panel>
                    </p:tab>
                    <p:tab title="Month">
                        <p:panel id="chartMonthPanel">
                            <center>
                                <h:outputText id="projectWiseMonthText" rendered="#{systemUtilizationServiceBean.projectFlag}" value="Project Wise Month Update"/>
                                <p:columnChart id="projectWiseMonthUpdateChart" rendered="#{systemUtilizationServiceBean.projectFlag}" value="#{systemUtilizationServiceBean.monthUpdateCounts}" var="monthWiseUpdate" xfield="#{monthWiseUpdate.name}" height="200px" width="640px">
                                    <p:chartSeries label="Project Wise Current Month Update" value="#{monthWiseUpdate.noUpdates}"/>
                                </p:columnChart>
                                <h:outputText id="resourceWiseMonthText" rendered="#{systemUtilizationServiceBean.resourceFlag}" value="Resource Wise Month Update"/>
                                <p:columnChart id="resourceWiseMonthUpdateChart" rendered="#{systemUtilizationServiceBean.resourceFlag}" value="#{systemUtilizationServiceBean.monthUpdateCounts}" var="monthWiseResourceUpdate" xfield="#{monthWiseResourceUpdate.name}" height="200px" width="640px">
                                    <p:chartSeries label="Resource Wise Current Month Update" value="#{monthWiseResourceUpdate.noUpdates}"/>
                                </p:columnChart>
                            </center>
</p:panel>
                    </p:tab>
                </p:tabView>
            </p:panel>

现在，我必须使用与上述相同的选项卡在其他 tabview 中显示相同的数据，唯一的事情是现在我必须在饼图中显示。现在在饼图中，我使用相同的列表。因此，它将再次从数据库中获取数据并浪费时间。为了解决这个问题，我创建了其他三个列表，并且只提供了那些先前列表的引用。所以，现在没有发生数据库提取。

应用引用的代码是:

public List<UpdateCount> getPieDayUpdateCounts() {

        pieDayUpdateCounts = dayUpdateCounts;
        return pieDayUpdateCounts;
    }

    public List<UpdateCount> getPieMonthUpdateCounts() {
        pieMonthUpdateCounts = monthUpdateCounts;
        return pieMonthUpdateCounts;
    }

    public List<UpdateCount> getPieWeekUpdateCounts() {
        pieWeekUpdateCounts = weekUpdateCounts;
        return pieWeekUpdateCounts;
    } 

但是，这里发生的问题是仅显示启用了该选项卡的图表，而其余 2 个选项卡未显示任何图表。

UI的代码是:

<p:tabView dynamic="false" cache="false">
                <p:tab title="Day">
                    <center>
                        <p:panel id="pieChartDayPanel">
                            <h:outputText id="projectWiseDayPieChartText" rendered="#{systemUtilizationServiceBean.projectFlag}" value="Project Wise Day Update"/>
                            <p:pieChart id="projectWiseDayUpdatePieChart" rendered="#{systemUtilizationServiceBean.projectFlag}" value="#{systemUtilizationServiceBean.dayUpdateCounts}" var="dayWisePieUpdate" categoryField="#{dayWisePieUpdate.name}" dataField="#{dayWisePieUpdate.noUpdates}" height="200" width="200"/>
                            <h:outputText id="resourceWiseDayPieChartText" rendered="#{systemUtilizationServiceBean.resourceFlag}" value="Resource Wise Day Update"/>
                            <p:pieChart id="resourceWiseDayUpdatePieChart" rendered="#{systemUtilizationServiceBean.resourceFlag}" value="#{systemUtilizationServiceBean.dayUpdateCounts}" var="dayWiseResourcePieUpdate" categoryField="#{dayWiseResourcePieUpdate.name}" dataField="#{dayWiseResourcePieUpdate.noUpdates}" height="200" width="200"/>
                        </p:panel>
                    </center>
                </p:tab>
                <p:tab title="Week">
                    <center>
                        <p:panel id="pieChartWeekPanel">
                            <h:outputText id="projectWiseWeekPieChartText" rendered="#{systemUtilizationServiceBean.projectFlag}" value="Project Wise Week Update"/>
                            <p:pieChart id="projectWiseWeekUpdatePieChart" rendered="#{systemUtilizationServiceBean.projectFlag}" value="#{systemUtilizationServiceBean.weekUpdateCounts}" var="weekWisePieUpdate" categoryField="#{weekWisePieUpdate.name}" dataField="#{weekWisePieUpdate.noUpdates}" height="200" width="200"/>
                            <h:outputText id="resourceWiseWeekPieChartText" rendered="#{systemUtilizationServiceBean.resourceFlag}" value="Resource Wise Week Update"/>
                            <p:pieChart id="resourceWiseWeekUpdatePieChart" rendered="#{systemUtilizationServiceBean.resourceFlag}" value="#{systemUtilizationServiceBean.weekUpdateCounts}" var="weekWiseResourcePieUpdate" categoryField="#{weekWiseResourcePieUpdate.name}" dataField="#{weekWiseResourcePieUpdate.noUpdates}" height="200" width="200"/>
                        </p:panel>
                    </center>
                </p:tab>
                <p:tab title="Month">
                    <center>
                        <p:panel id="pieChartMonthPanel">
                            <h:outputText id="projectWiseMonthPieChartText" rendered="#{systemUtilizationServiceBean.projectFlag}" value="Project Wise Month Update"/>
                            <p:pieChart id="projectWiseMonthUpdatePieChart" rendered="#{systemUtilizationServiceBean.projectFlag}" value="#{systemUtilizationServiceBean.monthUpdateCounts}" var="monthWisePieUpdate" categoryField="#{monthWisePieUpdate.name}" dataField="#{monthWisePieUpdate.noUpdates}" height="200" width="200"/>
                            <h:outputText id="resourceWiseMonthPieChartText" rendered="#{systemUtilizationServiceBean.resourceFlag}" value="Resource Wise Month Update"/>
                            <p:pieChart id="resourceWiseMonthUpdatePieChart" rendered="#{systemUtilizationServiceBean.resourceFlag}" value="#{systemUtilizationServiceBean.monthUpdateCounts}" var="monthWiseResourcePieUpdate" categoryField="#{monthWiseResourcePieUpdate.name}" dataField="#{monthWiseResourcePieUpdate.noUpdates}" height="200" width="200"/>
                        </p:panel>
                    </center>
                </p:tab>
            </p:tabView>

这背后的原因应该是什么？

Answer 1

与其尝试保留列表的多个副本，不如使用 JSF 范围来管理获取它们的时间/频率。

将您的支持 bean 范围限定为 RequestScoped 或 ViewScoped，创建一个从数据库中获取列表的方法(如果使用 CDI，则注释方法 @PostConstruct，否则使用 PreRenderViewEvent 或在构造函数本身中调用它)。现在通过简单的 getter 访问您的列表。