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JSF、RichFaces、分页

转载 作者:行者123 更新时间:2023-12-04 08:27:46 30 4
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我知道这里有很多关于 JSF 分页的帖子,但没有一个让我满意。

要将相当大的数据拆分成页面,我将使用 RichFaces Data 滚动组件。

它似乎适合这种情况,但它看起来像是“人工”分页。

我不喜欢这里的是它加载所有数据,然后只显示其中的一部分。至少它似乎是这样做的。如果我错了纠正我。

丰富的面孔有很好的演示,但由于某种原因,他们跳过了 bean 定义——只有 xhtml。
我看到有人提到了 ExtendedDataModel,但我发现的唯一例子并没有给我留下深刻印象。
为什么我应该有 5 个屏幕代码只显示数据的子集?

老实说,像分页这样简单的问题在 JSF 中碰巧非常复杂,我真的不明白为什么。

所以我的问题是:
1. Richfaces 可以只加载一页数据吗
2.不将其存储到 session 中(我的意思是实际数据未列出状态-当前页面等)

我只对 Richfaces lib 感兴趣,因为我已经在我的项目中使用了它,并且不知道要引入对其他东西的依赖

提前谢谢

最佳答案

在 RichFaces 论坛上讨论后,提出了以下解决方案(感谢 Brendan Healey):

RichLazyDataModel.java

/**
* Extended data model
* @author Brendan Healey
*/
public abstract class RichLazyDataModel<T> extends ExtendedDataModel<T> {

private SequenceRange cachedRange;
private Integer cachedRowCount;
private List<T> cachedList;
private Object rowKey;

public abstract List<T> getDataList(int firstRow, int numRows);
public abstract Object getKey(T t);
public abstract int getTotalCount();

@Override
public void walk(FacesContext ctx, DataVisitor dv, Range range, Object argument) {

SequenceRange sr = (SequenceRange) range;

if (cachedList == null || !equalRanges(cachedRange, sr)) {
cachedList = getDataList(sr.getFirstRow(), sr.getRows());
cachedRange = sr;
}

for (T t : cachedList) {
if (getKey(t) == null) {
/*
* the 2nd param is used to build the client id of the table
* row, i.e. mytable:234:inputname, so don't let it be null.
*/
throw new IllegalStateException("found null key");
}
dv.process(ctx, getKey(t), argument);
}

}


/*
* The rowKey is the id from getKey, presumably obtained from
* dv.process(...).
*/
@Override
public void setRowKey(Object rowKey) {
this.rowKey = rowKey;
}

@Override
public Object getRowKey() {
return rowKey;
}

@Override
public boolean isRowAvailable() {
return (getRowData() != null);
}

@Override
public int getRowCount() {
if (cachedRowCount == null) {
cachedRowCount = getTotalCount();
}
return cachedRowCount;
}

@Override
public T getRowData() {
for (T t : cachedList) {
if (getKey(t).equals(this.getRowKey())) {
return t;
}
}
return null;
}

protected static boolean equalRanges(SequenceRange range1, SequenceRange range2) {
if (range1 == null || range2 == null) {
return range1 == null && range2 == null;
} else {
return range1.getFirstRow() == range2.getFirstRow() && range1.getRows() == range2.getRows();
}
}



/*
* get/setRowIndex are used when doing multiple select in an
* extendedDataTable, apparently. Not tested. Actually, the get method is
* used when using iterationStatusVar="it" & #{it.index}.
*/
@Override
public int getRowIndex() {
if (cachedList != null) {
ListIterator<T> it = cachedList.listIterator();
while (it.hasNext()) {
T t = it.next();
if (getKey(t).equals(this.getRowKey())) {
return it.previousIndex() + cachedRange.getFirstRow();
}
}
}
return -1;
}

@Override
public void setRowIndex(int rowIndex) {
int upperBound = cachedRange.getFirstRow() + cachedRange.getRows();
if (rowIndex >= cachedRange.getFirstRow() && rowIndex < upperBound) {
int index = rowIndex % cachedRange.getRows();
T t = cachedList.get(index);
setRowKey(getKey(t));
}
}

@Override
public Object getWrappedData() {
throw new UnsupportedOperationException("Not supported yet.");
}

@Override
public void setWrappedData(Object data) {
throw new UnsupportedOperationException("Not supported yet.");

}

public List<T> getCachedList() {
return cachedList;
}

}

列表状态
/**
* Holds list state
*/
public class ListState implements Serializable {

private int page;

private Map<String, Serializable> searchCriteria = new HashMap<String, Serializable>();

public int getPage() {
return page;
}

public void setPage(int page) {
this.page = page;
}

public Map<String,Serializable> getSearchCriteria() {
return searchCriteria;
}

}

CardsBean.java
@ManagedBean(name="cardsBean")
public class CardsBean {

@ManagedProperty("#{cardService}")
private CardService cardService;

private ListState state;

private RichLazyDataModel<Card> cardsModel = new RichLazyDataModel<Card>() {
@Override
public List<Card> getDataList(int firstRow, int numRows) {
MyUserDetails user = SecurityUtils.getCurrentUser();
return cardService.findUserCards(user.getUser(), firstRow, numRows, state.getSearchCriteria());
}

@Override
public Object getKey(Card card) {
return card.getId();
}

@Override
public int getTotalCount() {
MyUserDetails user = SecurityUtils.getCurrentUser();
return cardService.countUserCards(user.getUser(), state.getSearchCriteria());
}
};


public RichLazyDataModel<Card> getCards() {
return cardsModel;
}

public String getSearchString() {
return (String)state.getSearchCriteria().get("searchString");
}

public int getCurrentPage() {
return state.getPage();
}

public void setCurrentPage(int page) {
state.setPage(page);
}

public void setSearchString(String searchString) {
state.getSearchCriteria().put("searchString", searchString);
}

public void setCardService(CardService cardService) {
this.cardService = cardService;
}

public boolean isPinned() {
return Boolean.TRUE.equals(state.getSearchCriteria().get("pinned"));
}

public void setPinned(boolean pinned) {
state.getSearchCriteria().put("pinned", pinned);
}

public void togglePinned() {
setPinned(!isPinned());
}

@PostConstruct
public void init() {
state = getFromSession("cardsList", null);
if (state == null) {
state = new ListState();
storeInSession("cardsList", state);
}
}

public <T extends Serializable> T getFromSession(String name, T defaultValue) {
T ret = (T) FacesContext.getCurrentInstance().getExternalContext().getSessionMap().get(name);
if (ret == null) {
ret = defaultValue;
}
return ret;
}

public void storeInSession(String name, Serializable obj) {
FacesContext.getCurrentInstance().getExternalContext().getSessionMap().put(name, obj);
}
}

card.xhtml(部分)
...

<h:form>

<rich:dataGrid value="#{cardsBean.cards}" var="card" columns="2" elements="20" first="#{cardsBean.currentPage}" style="margin:0 auto;width:70em" id="cardsTable">
<f:facet name="header">
<h:inputText value="#{cardsBean.searchString}">
<a4j:ajax event="keyup" render="cardsTable@body, cardsTable@footer">
<a4j:attachQueue requestDelay="700" ignoreDupResponses="true" />
</a4j:ajax>

</h:inputText>
</f:facet>

<rich:panel id="cd">
<ui:include src="WEB-INF/parts/card.xhtml">
<ui:param name="card" value="#{card}"/>
</ui:include>


</rich:panel>

<f:facet name="footer">
<rich:dataScroller page="#{cardsBean.currentPage}" />
</f:facet>

</rich:dataGrid>

</h:form>
...

关于JSF、RichFaces、分页,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/11937660/

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