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Lazy JSF Primefaces Datatable Pagination – Part 2

    博客分类：
  • JSF
jsfPrimefacesDatatable pagination 
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Lazy JSF Primefaces Datatable Pagination – Part 2

The page code is very simple and there is no complication. Check the “index.xhtml” code: 
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:ui="http://java.sun.com/jsf/facelets"
    xmlns:h="http://java.sun.com/jsf/html" xmlns:f="http://java.sun.com/jsf/core" xmlns:p="http://primefaces.org/ui">
<h:head>
</h:head>
<h:body>
    <f:view>
        <h:form>
            <p:dataTable id="lazyDataTable" value="#{playerMB.allPlayers}" var="player" paginator="true" rows="10"
                selection="#{playerMB.player}" selectionMode="single"
                paginatorTemplate="{CurrentPageReport}  {FirstPageLink} {PreviousPageLink} {PageLinks} {NextPageLink} {LastPageLink} {RowsPerPageDropdown}"
                rowsPerPageTemplate="5,10,15" style="width: 80%;margin-left: 10%;margin-right: 10%;">

                <p:ajax event="rowSelect" update=":playerDialogForm" oncomplete="playerDetails.show()" />

                <p:column>
                    <f:facet name="header">Name</f:facet>
                    <h:outputText value="#{player.name}" />
                </p:column>
                <p:column>
                    <f:facet name="header">Age</f:facet>
                    <h:outputText value="#{player.age}" />
                </p:column>
            </p:dataTable>
        </h:form>

        <p:dialog widgetVar="playerDetails" header="Player" modal="true">
            <h:form id="playerDialogForm">
                <h:panelGrid columns="2">
                    <h:outputText value="Id: " />
                    <h:outputText value="#{playerMB.player.id}" />
                    <h:outputText value="Name: " />
                    <h:outputText value="#{playerMB.player.name}" />
                    <h:outputText value="Age: " />
                    <h:outputText value="#{playerMB.player.age}" />
                </h:panelGrid>
            </h:form>
        </p:dialog>
    </f:view>
</h:body>
</html>


We got a lazy datatable that will display a selected value in a dialog.

In our Managed Bean we have a simpler code than the page: 

package com.mb;

import java.io.Serializable;

import javax.faces.bean.ManagedBean;
import javax.faces.bean.ViewScoped;

import org.primefaces.model.LazyDataModel;

import com.model.Player;

@ViewScoped
@ManagedBean
public class PlayerMB implements Serializable {

    private static final long serialVersionUID = 1L;
    private LazyDataModel<Player> players = null;
    private Player player;

    public LazyDataModel<Player> getAllPlayers() {
        if (players == null) {
            players = new PlayerLazyList();
        }

        return players;
    }

    public Player getPlayer() {
        if(player == null){
            player = new Player();
        }

        return player;
    }

    public void setPlayer(Player player) {
        this.player = player;
    }
}


We got a get/set to the Player entity and a get to the an object of the LazyDataModel type.

Check bellow the implementation of the PlayerLazyList code: 

package com.mb;

import java.util.List;
import java.util.Map;

import org.primefaces.model.LazyDataModel;
import org.primefaces.model.SortOrder;

import com.connection.MyTransaction;
import com.dao.PlayerDAO;
import com.model.Player;

public class PlayerLazyList extends LazyDataModel<Player> {

    private static final long serialVersionUID = 1L;

    private List<Player> players;

    private MyTransaction transaction;

    private PlayerDAO playerDAO;

    @Override
    public List<Player> load(int startingAt, int maxPerPage, String sortField, SortOrder sortOrder, Map<String, String> filters) {
        try {
            try {
                transaction = MyTransaction.getNewTransaction();
                playerDAO =  new PlayerDAO(transaction);

                transaction.begin();

                // with datatable pagination limits
                players = playerDAO.findPlayers(startingAt, maxPerPage);

                // If there is no player created yet, we will create 100!!
                if (players == null || players.isEmpty()) {
                    playerDAO.create100Players();

                    // we will do the research again to get the created players
                    players = playerDAO.findPlayers(startingAt, maxPerPage);
                }
            } finally {
                transaction.commit();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

        // set the total of players
        if(getRowCount() <= 0){
            setRowCount(playerDAO.countPlayersTotal());
        }

        // set the page dize
        setPageSize(maxPerPage);

        return players;
    }

    @Override
    public Object getRowKey(Player player) {
        return player.getId();
    }

    @Override
    public Player getRowData(String playerId) {
        Integer id = Integer.valueOf(playerId);

        for (Player player : players) {
            if(id.equals(player.getId())){
                return player;
            }
        }

        return null;
    }
}


About the code above:

■The load method: the Primefaces will invoke this method every time that the pagination is fired. It will have all parameters with valid values; with these parameters you will be able to do a query in the database getting only for the needed data. If you want to sort your query by a field you can use the sortField attribute that will have the column datatable value (it will be null if the user do not order); the sortOrder will indicate if the user wants ascending or descending.
■The getRowKey method: this method return an id to each line, the Primefaces will invoke this method when needed.
■The getRowData method: will return a selected Player in the datatable.
■When you run this application the first time it will persist 100 players in the database. In a real application this would not be necessary.

A last configuration need to be added in the “web.xml” file: 

<persistence-context-ref>
    <persistence-context-ref-name>JSFPU</persistence-context-ref-name>
    <persistence-unit-name>JSFPU</persistence-unit-name>
</persistence-context-ref>


We will use this configuration to do the JNDI Lookup.

Running our application

Now we just need to start up the application.

To access the application you can use the link:

http://localhost:8080/DatatableLazyPrimefaces/

from:http://www.javacodegeeks.com/2012/04/lazy-jsf-primefaces-datatable_11.html
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