原理是滚动与Lazy加载兼容 [英] Is primefaces live scrolling compatible with Lazy loading

问题描述

我有一个数据表需要显示巨大的数据集，所以我决定用原始图形滚动。我还要知道，为了提高数据表的性能，我们需要实现延迟加载。参考标题显示示例
here ，我观察到在那里语句

，当分页，排序，过滤或活动滚动时，需要实现一个LazyDataModel来查询数据源发生

现在滚动被提到，但我看不到代码来处理滚动。它只有代码来处理排序，过滤，行计数和分页。有人可以澄清我的困惑，如果两个现场挑逗和懒惰的数据模型实现是相互兼容的，或者我应该添加一些代码来处理实时滚动。

这里有一个小例子：

xhtml

 < p： dataTable var =user
 value =＃{bean.lazyDataModel}
 scrollRows =20
 liveScroll =true
 scrollHeight =500
 lazy =true
 scrollable =true> 
 
< p：column headerText =name> 
< h：outputText value =＃{user.name}/> 
< / p：column> 
 
< / p：dataTable> 
  

Bean

  @ManagedBean 
 @ViewScoped 
 public class Bean {
 
 private LazyDataModel< User> lazyDataModel; 
 
 @EJB 
 UserEJB userEJB; 
 
 @PostConstruct 
 public void init（）{
 lazyDataModel = new LazyUserModel（userEJB）; 
} 
 
 public LazyDataModel< User> getLazyDataModel（）{
 return lazyDataModel; 
} 
 
 public void setLazyDataModel（LazyDataModel< User> lazyDataModel）{
 this.lazyDataModel = lazyDataModel; 
} 
 
 // userEJB的设置者和获取者
} 
  

LazyUserModel

  public class LazyUserModel extends LazyDataModel< User> ; {
 private Integer findAllCount; 
 
 @EJB 
 private UserEJB userEJB; 
 
 public LazyUserModel（UserEJB userEJB）{
 this.userEJB = userEJB; 
} 
 
 
 @Override 
 public List< User> load（int first，int pageSize，String sortField，SortOrder sortOrder，
 Map< String，String> filters）{
 
列表< User> data = new ArrayList< User>（）; 
 // pageSize是在dataable 
 data = userEJB.findAll（first，pageSize）中的scrollRows =20; 
 // findAll正在使用query.setFirstResult（first）.setMaxResults（pageSize）.getResultList（）
 
 // rowCount 
 if（findAllCount == null）{
 findAllCount = userEJB.findAllCount（）; 
 this.setRowCount（findAllCount）; 
} 
 
返回数据; 
} 
 
} 
  

希望这有帮助。 >

I have a datatable where huge data sets need to be displayed.So i decided to go with primefaces live scrolling.I also got to know that to improve datatable performance with huge data sets we need to implement lazy loading.With reference to the primefaces showcase example here,what i observed that there in the statement

, a LazyDataModel needs to be implemented to query the datasource when pagination, sorting, filtering or live scrolling happens

live scrolling is mentioned but i cannot see the code to handle scrolling.It only has the code to handle sorting,filtering,row count and pagination.Can someone please clarify my confusion if both live scolling and lazy datamodel implementation are compatible with each other or should i add some code to handle live scrolling also.

解决方案

It works exactly the same as if you were having a pagination.

Here's a small example:

xhtml

<p:dataTable var="user"
        value="#{bean.lazyDataModel}"
        scrollRows="20"
        liveScroll="true"
        scrollHeight="500"
        lazy="true"
        scrollable="true">

        <p:column headerText="name">
           <h:outputText value="#{user.name}" />
        </p:column>

</p:dataTable>

Bean

@ManagedBean
@ViewScoped
public class Bean {

    private LazyDataModel<User> lazyDataModel;

    @EJB
    UserEJB userEJB;

    @PostConstruct
    public void init() {
       lazyDataModel = new LazyUserModel(userEJB);
    }

    public LazyDataModel<User> getLazyDataModel() {
        return lazyDataModel;
    }

    public void setLazyDataModel(LazyDataModel<User> lazyDataModel) {
       this.lazyDataModel = lazyDataModel;
    }

   //setters and getters for userEJB
}

LazyUserModel

public class LazyUserModel extends LazyDataModel<User> {
   private Integer findAllCount;

   @EJB
   private UserEJB userEJB;

   public LazyUserModel(UserEJB userEJB) {
       this.userEJB = userEJB;
   }


   @Override
   public List<User> load(int first, int pageSize, String sortField, SortOrder sortOrder,
        Map<String, String> filters) {

       List<User> data = new ArrayList<User>();
       // pageSize is scrollRows="20" in the datatable
       data = userEJB.findAll(first, pageSize); 
       // findAll is using query.setFirstResult(first).setMaxResults(pageSize).getResultList()

      // rowCount
       if (findAllCount == null) {
           findAllCount = userEJB.findAllCount();
           this.setRowCount(findAllCount);
       }

       return data;
   }

}

Hope this helps.

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