Use List for source in datatable with lazyLoading

问题

I have the list with very data. I want to show data in Primeface data table with lazy loading ability. now I show data normal in data Table, but it is slow. How can use lazy loading ability?

XHTML File :

<ui:composition template="template.xhtml">
<ui:define name="content">
    <p:panel id="pnlLogInformationPage">
        <h:form id="logInformation">
            <div class="contentContainer-full-left">
                <p:dataTable var="log" value="#{logInformationMB.logInformationList}" id="logTable"
                    width="100%" liveResize="true">
                    <p:column headerText="ID" sortBy="Id">
                        <h:outputText value="#{logInformation.Id}" />
                    </p:column>
                    <p:column headerText="Name" sortBy="Name">
                        <h:outputText value="#{logInformation.Name}" />
                    </p:column>
                </p:dataTable>
            </div>
        </h:form>
    </p:panel>
</ui:define>

ManageBean File:

@ManagedBean(name = "logInformationMB")
@ViewScoped
public class LogManagedBean implements Serializable {
    @PostConstruct
    public void initComponents() {
        loadLogInformation();
    }
    public List<LogInformationDTO> getLogInformationList() {
        return logInformationList;
    }
    public void setLogInformationList(final List<LogInformationDTO> pLogInformationList) {
        logInformationList = pLogInformationList;
    }
    public void loadLoagInformation(final ComponentSystemEvent event) {
        setLogLInformationlist(getLogInformationList();
    }
    public void loadInformationProtokolle() {
        loadInformationProtokolle(null);
    }
    public List<LogInformationDTO> getLogInformation() {
        final List<LogInformationDTO> lcResult = new ArrayList<LogInformationDTO>();
        ....
        return lcResult;
    }
}

回答1:

According to your code, you didn't use lazyloading. you just get all your datas. It will be slow when your data is too big.

See my steps below:

1- Instead of using #{logInformationMB.logInformationList}, you need to create new class which extend LazyDataModel class and create a service that can get data page by page.

    public class LogInformationDataModel extends LazyDataModel<LogInformationDTO> {
          private List<LogInformationDTO> logInformationList;
          private LogInformationService logInformationService = new LogInformationService();

          @Override
            public List<LogInformationDTO> load(int first, int pageSize, String sortField, SortOrder sortOrder, Map<String, Object> filters) {
                // TODO implement sort

                setRowCount(logInformationService.count(filters));                  
                logInformationList = logInformationService.list(first / pageSize, pageSize, sortField, sort, filters);
                return logInformationList;
            }

          @Override
          public LogInformationDTO getRowData(String rowKey) {
              for(LogInformationDTO logInformation : logInformationList) {
                  if(logInformation.getId().equals(rowKey))
                      return logInformation;
              }
              return null;
          }

          @Override
          public Object getRowKey(LogInformationDTO logInformation) {
              return logInformation.getId();
          }
    }

2- Register data model in your Manage bean

    @ManagedBean(name = "logInformationMB")
    @ViewScoped
    public class LogManagedBean implements Serializable {

        private LogInformationDataModel dataModel = new LogInformationDataModel();

        public LogInformationDataModel getDataModel() {
          return dataModel;
        }

    }

3- Add lazy attribe (lazy="true") to your p:dataTable and using pagination

    <p:dataTable var="log" value="#{logInformationMB.dataModel}" var="logInformation" id="logTable"
        width="100%" 
        lazy="true"
        paginator="true" 
        paginatorPosition="bottom" 
        paginatorTemplate="{CurrentPageReport} {FirstPageLink} {PreviousPageLink} {PageLinks} {NextPageLink} {LastPageLink} {RowsPerPageDropdown}"
        rowsPerPageTemplate="10,50,100"
        >
        <p:column headerText="ID" sortBy="Id">
            <h:outputText value="#{logInformation.Id}" />
        </p:column>
        <p:column headerText="Name" sortBy="Name">
            <h:outputText value="#{logInformation.Name}" />
        </p:column>
    </p:dataTable>

I Hope my answer could solve your issue.

Below is the link you can check :

Primefaces lazydatamodel

来源：https://stackoverflow.com/questions/42069206/use-list-for-source-in-datatable-with-lazyloading