Primefaces懒惰过滤问题

Question

我正试图在应用程序中实现延迟加载，但我的过滤出现了问题。此时排序工作正常。在惰性过滤到位的情况下，数据表最初从表中加载正确的计数，即24条记录，但它会一次又一次地重复第一条和第二条记录。非常感谢您的帮助。

这是我的ScreenshotListProducer类代码：

@ManagedBean
@RequestScoped
public class ScreenshotListProducer implements Serializable  {
private static final long serialVersionUID = 1L;
@Inject
private EntityManager em;
private List<Screenshot> screenshots;
private LazyDataModel<Screenshot> lazyModel = null;
private int pageSize = 5;
public void setPageSize(int pageSize) {
this.pageSize = pageSize;
}
public int getPageSize() {
return pageSize;
}
@Produces
@Named
public List<Screenshot> getScreenshots() {
System.out.println("************* getting screenshots list **************");
return screenshots;
}
@PostConstruct
public void LoadData() {
lazyModel = new LazyDataModel<Screenshot>() {
private static final long serialVersionUID = 1L;
@Override
public List<Screenshot> load(int first, int pageSize, String sortField, SortOrder sortOrder, Map<String,String> filters) { 
int start = first;
int end = first + pageSize;
if (sortField == null) {
sortField = "time";
}
try {
CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<Screenshot> criteria = cb.createQuery(Screenshot.class);
Root<Screenshot> screenshot = criteria.from(Screenshot.class);
// sorting
if (sortOrder.equals(SortOrder.ASCENDING))
{
criteria.select(screenshot).orderBy(cb.asc(screenshot.get(sortField)));
}
else if (sortOrder.equals(SortOrder.DESCENDING))
{
criteria.select(screenshot).orderBy(cb.desc(screenshot.get(sortField)));
}
// From
Root<Screenshot> from = criteria.from(Screenshot.class);
List<Predicate> predicates = new ArrayList<Predicate>();
if (filters != null) {
// filters
for(Iterator<String> it = filters.keySet().iterator(); it.hasNext();) {
String filterProperty = it.next(); // table column name = field name
System.out.println("filterProperty is: " + filterProperty);
String filterValue = filters.get(filterProperty);
System.out.println("filterValue is: " + filterValue);
Expression<String> literal = cb.literal((String)filterValue);
predicates.add(cb.like(from.<String>get(filterProperty), literal));
}
criteria.where(predicates.toArray(new Predicate[predicates.size()]));
}
TypedQuery<Screenshot> s = em.createQuery(criteria);
s.setMaxResults(end - start);
s.setFirstResult(start);
screenshots = s.getResultList();
} catch (NullPointerException e) {
e.printStackTrace();
}
return screenshots;
}
};
lazyModel.setRowCount(24);
lazyModel.setPageSize(pageSize);
if (lazyModel.getRowIndex() == -1 || lazyModel.getPageSize() == 0) {
lazyModel.setRowIndex(-1);
}
else
lazyModel.setRowIndex(lazyModel.getRowIndex() % lazyModel.getPageSize());
}
public LazyDataModel<Screenshot> getLazyModel() {
return lazyModel;
}
}

这是我的截屏类：

@Entity
@XmlRootElement
@Table(name="Test2012", uniqueConstraints = @UniqueConstraint(columnNames = "id"))
public class Screenshot implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue
@Column(name = "id", columnDefinition="INT")
private Long id;
private Timestamp time;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public Timestamp getTime() {
return time;
}
public void setTime(Timestamp time) {
this.time = time;
}   
}

这是我的xhtml代码：

<p:dataTable id="table1" var="scrshot" rowKey="#{scrshot.id}" value="#{screenshotListProducer.lazyModel}" paginator="true" rows="7" paginatorPosition="bottom"
paginatorTemplate="{CurrentPageReport}  {FirstPageLink} {PreviousPageLink} {PageLinks} {NextPageLink} {LastPageLink} {RowsPerPageDropdown}" 
rowsPerPageTemplate="7,20,50,100" widgetVar="dataTable" currentPageReportTemplate="(Number of Records: {totalRecords})"
emptyMessage="No screenshot data found with given criteria" lazy="true" scrollable="true" draggableColumns="true" scrollHeight="217" style="width: 100%;"> 
<f:facet name="header"> 
</f:facet>
<p:column selectionMode="multiple"/> 
<p:column id="time" headerText="Time" sortBy="#{scrshot.time}" filterBy="#{scrshot.time}" filterMatchMode="startsWith"> 
<h:outputText value="#{scrshot.time}"/> 
</p:column>   
<p:column id="id" headerText="ID" sortBy="#{scrshot.id}" filterBy="#{scrshot.id}" filterOptions="#{scrshot.id}" filterMatchMode="exact"> 
<h:outputText value="#{scrshot.id}"/> 
</p:column> 
</p:dataTable>

底漆3.3.1Mojarra 2.1.5JBoss AS 7.1.0.最终

Answer 1

几句话：

• 您正在使用@RequestScoped。我似乎记得过滤/排序和请求范围的问题(不确定这是这里的问题)。请尝试@ViewScoped或更高的作用域
• 不要在顶层(backingbeans)中使用数据访问(例如EntityManager等与数据库相关的东西)。将其分为两层或三层：GUI(业务逻辑)-数据访问
• 你发布的ScreenshotListProducer类有一个混乱的缩进，很难阅读。它似乎也没有正确关闭(缺少一个"｝")
• JSF中的globalFilter似乎没有连接到数据表。(我可能错了。)
• 您似乎正在创建3个筛选器、2个列筛选器和1个全局筛选器，是哪一个导致了问题？下次更具体；-)
• 删除不相关的代码并精简代码，制作一个简短的示例来演示您的问题。示例：modeOptions和formatOptions似乎没有使用，只影响问题的可读性

Answer 2

感谢您的输入。我的加入问题与我的"来自"定义有关。我把它拿出来，用我原来的"屏幕截图"放在我的过滤器里，现在它过滤得很好。