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我有一个简单的 CRUD 项目，我正在使用 Richfaces 和 toplink。我注意到有些页面加载速度很慢，因此我将 toplink 的日志记录级别设置为 FINE。当加载我的页面时，我的页面在 Rich:datatable 中列出了我的所有课程对象，toplink 似乎正在运行相同的全选查询 9 次。当使用 rich:datascroller 移动到下一组 50 个项目或对列进行排序时，它再次运行相同的全选查询 18 次。

这是数据表：

<rich:dataTable value="#{CourseController.courses}"
                        id="table"
                        var="dataTableItem"
                        rendered="#{CourseController.courses.rowCount>0}"
                        rows="50"
                        onRowMouseOut="this.style.backgroundColor='#{a4jSkin.tableBackgroundColor}'"
                        onRowMouseOver="this.style.backgroundColor='#dcdcdc'">
            <f:facet name="header">
                <h:outputText value="Courses"/>
            </f:facet> 
            <rich:column sortBy="#{dataTableItem.id}">  
                <f:facet name="header">  
                    <h:outputText  value="ID"/>  
                </f:facet>  
                <h:commandLink action="#{CourseController.viewCourse}">  
                    <h:outputText value="#{dataTableItem.id}" /> 
                    <f:param name="id" value="#{dataTableItem.id}" />  
                </h:commandLink>
            </rich:column> 
            <rich:column sortBy="#{dataTableItem.name}">  
                <f:facet name="header">  
                    <h:outputText  value="Name"/>  
                </f:facet>  
                <h:outputText value="#{dataTableItem.name}" />  
            </rich:column>        
            <rich:column sortBy="#{dataTableItem.owner}">  
                <f:facet name="header">  
                    <h:outputText  value="Owner"/>  
                </f:facet>  
                <h:outputText value="#{dataTableItem.owner}" />  
            </rich:column>
            <rich:column rendered="#{LoginController.inSystemAdminGroup || LoginController.inOperationsManagerGroup || LoginController.inLogisticsCoordinatorGroup}">  
                <f:facet name="header">  
                    <h:outputText  value=""/>  
                </f:facet>  
                <h:commandLink action="#{CourseController.editCourse}">  
                    <h:outputText value="Edit/Delete"/>  
                    <f:param name="id" value="#{dataTableItem.id}" />  
                </h:commandLink>  
            </rich:column>
            <f:facet name="footer">
                <rich:datascroller id="datascroller" />
            </f:facet>
        </rich:dataTable>

我的控制器中由表调用的函数：

public DataModel getCourses() {
        System.out.println("Im in getCourses.  Fun Fun Fun.");
        model = new ListDataModel(courseFacade.findAll());
        return model;
    }

getCourses() 函数调用我的 bean 中的函数：

public List<Course> findAll() {
        System.out.println("Selectin all the courses in the freaking database!!!!!!!!!!!!!!!!!!!!!!");
        Query q = em.createQuery("select object(o) from Course as o WHERE o.deleted = FALSE ORDER BY o.name");
        List<Course> courses = q.getResultList();
        return courses;
    }

加载带有表格的页面时我的控制台输出：

Im in getCourses.  Fun Fun Fun.
Selectin all the courses in the freaking database!!!!!!!!!!!!!!!!!!!!!!
SELECT ID, MODIFIEDBY, ACRONYM, EMSID, DELETED, REMINDEREMAILTEXT, DATEADDED, NUMDAYSREMINDER, DATEDELETED, ADHOC, DATEMODIFIED, ADDEDBY, OWNER, DELETEDBY, OPTLOCK, NAME FROM COURSE WHERE (DELETED = ?) ORDER BY NAME ASC
        bind => [false]
Im in getCourses.  Fun Fun Fun.
Selectin all the courses in the freaking database!!!!!!!!!!!!!!!!!!!!!!
SELECT ID, MODIFIEDBY, ACRONYM, EMSID, DELETED, REMINDEREMAILTEXT, DATEADDED, NUMDAYSREMINDER, DATEDELETED, ADHOC, DATEMODIFIED, ADDEDBY, OWNER, DELETEDBY, OPTLOCK, NAME FROM COURSE WHERE (DELETED = ?) ORDER BY NAME ASC
        bind => [false]
Im in getCourses.  Fun Fun Fun.
Selectin all the courses in the freaking database!!!!!!!!!!!!!!!!!!!!!!
SELECT ID, MODIFIEDBY, ACRONYM, EMSID, DELETED, REMINDEREMAILTEXT, DATEADDED, NUMDAYSREMINDER, DATEDELETED, ADHOC, DATEMODIFIED, ADDEDBY, OWNER, DELETEDBY, OPTLOCK, NAME FROM COURSE WHERE (DELETED = ?) ORDER BY NAME ASC
        bind => [false]
Im in getCourses.  Fun Fun Fun.
Selectin all the courses in the freaking database!!!!!!!!!!!!!!!!!!!!!!
SELECT ID, MODIFIEDBY, ACRONYM, EMSID, DELETED, REMINDEREMAILTEXT, DATEADDED, NUMDAYSREMINDER, DATEDELETED, ADHOC, DATEMODIFIED, ADDEDBY, OWNER, DELETEDBY, OPTLOCK, NAME FROM COURSE WHERE (DELETED = ?) ORDER BY NAME ASC
        bind => [false]
Im in getCourses.  Fun Fun Fun.
Selectin all the courses in the freaking database!!!!!!!!!!!!!!!!!!!!!!
SELECT ID, MODIFIEDBY, ACRONYM, EMSID, DELETED, REMINDEREMAILTEXT, DATEADDED, NUMDAYSREMINDER, DATEDELETED, ADHOC, DATEMODIFIED, ADDEDBY, OWNER, DELETEDBY, OPTLOCK, NAME FROM COURSE WHERE (DELETED = ?) ORDER BY NAME ASC
        bind => [false]
Im in getCourses.  Fun Fun Fun.
Selectin all the courses in the freaking database!!!!!!!!!!!!!!!!!!!!!!
SELECT ID, MODIFIEDBY, ACRONYM, EMSID, DELETED, REMINDEREMAILTEXT, DATEADDED, NUMDAYSREMINDER, DATEDELETED, ADHOC, DATEMODIFIED, ADDEDBY, OWNER, DELETEDBY, OPTLOCK, NAME FROM COURSE WHERE (DELETED = ?) ORDER BY NAME ASC
        bind => [false]
Im in getCourses.  Fun Fun Fun.
Selectin all the courses in the freaking database!!!!!!!!!!!!!!!!!!!!!!
SELECT ID, MODIFIEDBY, ACRONYM, EMSID, DELETED, REMINDEREMAILTEXT, DATEADDED, NUMDAYSREMINDER, DATEDELETED, ADHOC, DATEMODIFIED, ADDEDBY, OWNER, DELETEDBY, OPTLOCK, NAME FROM COURSE WHERE (DELETED = ?) ORDER BY NAME ASC
        bind => [false]
Im in getCourses.  Fun Fun Fun.
Selectin all the courses in the freaking database!!!!!!!!!!!!!!!!!!!!!!
SELECT ID, MODIFIEDBY, ACRONYM, EMSID, DELETED, REMINDEREMAILTEXT, DATEADDED, NUMDAYSREMINDER, DATEDELETED, ADHOC, DATEMODIFIED, ADDEDBY, OWNER, DELETEDBY, OPTLOCK, NAME FROM COURSE WHERE (DELETED = ?) ORDER BY NAME ASC
        bind => [false]
Im in getCourses.  Fun Fun Fun.
Selectin all the courses in the freaking database!!!!!!!!!!!!!!!!!!!!!!
SELECT ID, MODIFIEDBY, ACRONYM, EMSID, DELETED, REMINDEREMAILTEXT, DATEADDED, NUMDAYSREMINDER, DATEDELETED, ADHOC, DATEMODIFIED, ADDEDBY, OWNER, DELETEDBY, OPTLOCK, NAME FROM COURSE WHERE (DELETED = ?) ORDER BY NAME ASC
        bind => [false]
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1 回答 1

2

JSF 规范不保证每个生命周期请求只调用一次 getter，不要在 getter 中放置昂贵的代码（即，您正在执行查询并在每次调用 getCourses 时创建数据模型，JSF 规范允许调用此方法与框架一样多需要每个请求）。

于 2009-09-05T14:53:24.967 回答