package com.jsecode.util.pagination;
import java.util.ArrayList;
import java.util.List;
import javax.faces.context.FacesContext;
import javax.faces.model.DataModel;
import com.gcoresoft.jsfdemo.bean.CarBeanDAO;
public class DataScrollerList extends BasePagedBackingBean
{
CarBeanDAO dao = null;
public DataScrollerList()
{
dao = new CarBeanDAO();
}
public int getTotalCount()
{
int totalCount = 0;
totalCount = dao.getTotalCount();
return totalCount;
}
/** *//**
*
* 在DataScrollerList这个 Backing Bean中加一些东西，<br>
*
* 调用业务逻辑，并将数据交给PagedListDataModel，来帮我们完成最后的分页工作。
*
*/
public DataPage getDataPage(int startRow, int pageSize)
{
DataPage dataPage = dao.getDataPage(startRow, pageSize);
return dataPage;
}
}
JSP页面：
<f:view>
<h:form>
<rich:dataTable id="carList" width="483" rows="12" columnClasses="col"
value="#{scrollerList.dataModel}" var="car">
<f:facet name="header">
<rich:columnGroup>
<h:column>
<h:outputText styleClass="headerText" value="Name" />
</h:column>
<h:column>
<h:outputText styleClass="headerText" value="Decription" />
</h:column>
<h:column>
<h:outputText styleClass="headerText" value="Base Price" />
</h:column>
<h:column>
<h:outputText styleClass="headerText" value="Time" />
</h:column>
<h:column>
<h:outputText styleClass="headerText" value="操作操作" />
</h:column>
</rich:columnGroup>
</f:facet>
<h:column>
<h:outputText value="#{car.name}" />
</h:column>
<h:column>
<h:outputText value="#{car.description}" />
</h:column>
<h:column>
<h:outputText value="#{car.baseprice}" />
</h:column>
<h:column>
<h:outputText value="#{car.timestamp}" />
</h:column>
<h:column>
<h:commandLink action="#{user.delete}" value="删除" >
<f:param name="id" value="#{car.id}"/>
</h:commandLink>
</h:column>
</rich:dataTable>
<rich:datascroller for="carList" id="dc1"
style="width:483px" page="#{user.scrollerPage}"/>
</h:form>
</f:view>
faces-config.xml:
<managed-bean>
<managed-bean-name>scrollerList</managed-bean-name>
<managed-bean-class>com.jsecode.util.pagination.DataScrollerList</managed-bean-class>
<managed-bean-scope>session</managed-bean-scope>
</managed-bean>
DataPage.java:
package com.jsecode.util.pagination;
import java.util.List;
public class DataPage
{
/** *//**
* 将需要的页的数据封装到一个DataPage中去， 这个类表示了我们需要的一页的数据，<br>
* 里面包含有三个元素：datasetSize，startRow，和一个用于表示具体数据的List。<br>
* datasetSize表示了这个记录集的总条数，查询数据的时候，使用同样的条件取count即可，<br>
* startRow表示该页的起始行在数据库中所有记录集中的位置
*/
private int datasetSize;
private int startRow;
private List data;
/** *//**
*
* @param datasetSize
* 数据集大小
* @param startRow
* 起始行
* @param data
* 数据list
*/
public DataPage(int datasetSize, int startRow, List data)
{
this.datasetSize = datasetSize;
this.startRow = startRow;
this.data = data;
}
/** *//**
*
* @return
*/
public int getDatasetSize()
{
return datasetSize;
}
public int getStartRow()
{
return startRow;
}
/** *//**
*
* @return 已填充好的数据集
*/
public List getData()
{
return data;
}
}
PagedListDataModel.java:
package com.jsecode.util.pagination;
import javax.faces.model.DataModel;
/** *//**
* A special type of JSF DataModel to allow a datatable and datascroller to page
* through a large set of data without having to hold the entire set of data in
* memory at once.
* <p>
* Any time a managed bean wants to avoid holding an entire dataset, the managed
* bean should declare an inner class which extends this class and implements
* the fetchData method. This method is called as needed when the table requires
* data that isn\'t available in the current data page held by this object.
* <p>
* This does require the managed bean (and in general the business method that
* the managed bean uses) to provide the data wrapped in a DataPage object that
* provides info on the full size of the dataset.
*/
/** *//**
*
* 这个类里面的方法被dataTable调用顺序为：<br>
*
* 1.构造函数public PagedListDataModel(int pageSize) <br>
*
* 2.getRowCount()<br>
*
* 3.setRowIndex()<br>
*
* 4.public boolean isRowAvailable()<br>
*
* 5.public Object getRowData()
*
*/
public abstract class PagedListDataModel extends DataModel
{
int pageSize;
int rowIndex;
private int rowCount = -1;
DataPage page;
/** *//**
*
* Create a datamodel that pages through the data showing the specified
*
* number of rows on each page.
*
*/
public PagedListDataModel(int pageSize)
{
super();
this.pageSize = pageSize;
this.rowIndex = -1;
this.page = null;
}
/** *//**
*
* Not used in this class; data is fetched via a callback to the fetchData
*
* method rather than by explicitly assigning a list.
*
*/
public void setWrappedData(Object o)
{
if ( o instanceof DataPage ) {
this.page = (DataPage) o;
} else {
throw new UnsupportedOperationException("setWrappedData");
}
}
public int getRowIndex()
{
return rowIndex;
}
/** *//**
*
* Specify what the "current row" within the dataset is. Note that the
*
* UIData component will repeatedly call this method followed by getRowData
*
* to obtain the objects to render in the table.
*
*/
public void setRowIndex(int index)
{
rowIndex = index;
}
/** *//**
*
* Return the total number of rows of data available (not just the number of
*
* rows in the current page!).
*
*/
public int getRowCount()
{
if ( rowCount < 0 ) {
rowCount = fetchRowCount();
}
return rowCount;
}
/** *//**
*
* Return a DataPage object; if one is not currently available then fetch
*
* one. Note that this doesn\'t ensure that the datapage returned includes
*
* the current rowIndex row; see getRowData.
*
*/
private DataPage getPage(String name)
{
if ( page != null ) {
return page;
}
int rowIndex = getRowIndex();
int startRow = rowIndex;
if ( rowIndex == -1 ) {
// even when no row is selected, we still need a page
// object so that we know the amount of data available.
startRow = 0;
}
// invoke method on enclosing class
page = fetchPage(startRow, pageSize);
return page;
}
/** *//** */
/** *//**
*
* Return the object corresponding to the current rowIndex. If the DataPage
*
* object currently cached doesn\'t include that index then fetchPage is
*
* called to retrieve the appropriate page.
*
*/
public Object getRowData()
{
if ( rowIndex < 0 ) {
throw new IllegalArgumentException(
"Invalid rowIndex for PagedListDataModel; not within page");
}
// ensure page exists; if rowIndex is beyond dataset size, then
// we should still get back a DataPage object with the dataset size
// in it
if ( page == null ) {
page = fetchPage(rowIndex, pageSize);
rowCount = page.getDatasetSize();//
}
int datasetSize = page.getDatasetSize();
int startRow = page.getStartRow();
int nRows = page.getData().size();
int endRow = startRow + nRows;
if ( rowIndex >= datasetSize ) {
throw new IllegalArgumentException("Invalid rowIndex");
}
if ( rowIndex < startRow ) {// 向前取数据
page = fetchPage(rowIndex, pageSize);
rowCount = page.getDatasetSize();
startRow = page.getStartRow();
} else if ( rowIndex >= endRow ) { // 向后取数据
page = fetchPage(rowIndex, pageSize);
rowCount = page.getDatasetSize();//
startRow = page.getStartRow();
}
return page.getData().get(rowIndex - startRow);
}
public Object getWrappedData()
{
return page.getData();
}
/** *//** */
/** *//**
*
* Return true if the rowIndex value is currently set to a value that
*
* matches some element in the dataset. Note that it may match a row that is
*
* not in the currently cached DataPage; if so then when getRowData is
*
* called the required DataPage will be fetched by calling fetchData.
*
*/
public boolean isRowAvailable()
{
DataPage page = getPage("isRowAvailable");
if ( page == null ) {
return false;
}
int rowIndex = getRowIndex();
if ( rowIndex < 0 ) {
return false;
} else if ( rowIndex >= page.getDatasetSize() ) {
return false;
} else {
return true;
}
}
/** *//** */
/** *//**
*
* Method which must be implemented in cooperation with the managed bean
*
* class to fetch data on demand.
*
*/
public abstract DataPage fetchPage(int startRow, int pageSize);
public abstract int fetchRowCount();
}
BasePagedBackingBean:
package com.jsecode.util.pagination;
import javax.faces.model.DataModel;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
public abstract class BasePagedBackingBean
{
protected abstract DataPage getDataPage(int startRow, int pageSize);
public abstract int getTotalCount();
private DataModel dataModel;
private int i = 0;
// 为什么getDataModel这个方法要调用两次？非常不解啊
public DataModel getDataModel()
{
if ( dataModel == null ) {
dataModel = new LocalDataModel(10);
}
return dataModel;
}
public Object getBean(String beanName)
{
return null;
}
private class LocalDataModel extends PagedListDataModel
{
public LocalDataModel(int pageSize)
{
super(pageSize);
}
public int fetchRowCount()
{
return getTotalCount();
}
public DataPage fetchPage(int startRow, int pageSize)
{
// call enclosing managed bean method to fetch the data
return getDataPage(startRow, pageSize);
}
}
}
DataScrollerList.java:
package com.jsecode.util.pagination;
import java.util.ArrayList;
import java.util.List;
import javax.faces.context.FacesContext;
import javax.faces.model.DataModel;
import com.gcoresoft.jsfdemo.bean.CarBeanDAO;
public class DataScrollerList extends BasePagedBackingBean
{
CarBeanDAO dao = null;
public DataScrollerList()
{
dao = new CarBeanDAO();
}
public int getTotalCount()
{
int totalCount = 0;
totalCount = dao.getTotalCount();
return totalCount;
}
/** *//**
*
* 在DataScrollerList这个 Backing Bean中加一些东西，<br>
*
* 调用业务逻辑，并将数据交给PagedListDataModel，来帮我们完成最后的分页工作。
*
*/
public DataPage getDataPage(int startRow, int pageSize)
{
DataPage dataPage = dao.getDataPage(startRow, pageSize);
return dataPage;
}
}
每个DAO都实现了这个接口:
package com.gcoresoft.jsfdemo.bean;
import java.util.List;
import com.jsecode.util.pagination.DataPage;
/** *//**
* @author TiGERTiAN tigertian@gmail.com
* @version
* Oct 29, 2008 9:46:55 AM
*/
public interface Pagination
{
public int getTotalCount();
public DataPage getDataPage(int startRow, int pageSize);
public List getPagedList(int startRow, int pageSize);
}
DAO中的相关代码:
public DataPage getDataPage(int startRow, int pageSize)
{
// TODO Auto-generated method stub
return new DataPage(getTotalCount(), startRow, getPagedList(startRow, pageSize));
}
public int getTotalCount()
{
Query q = EntityManagerHelper.createQuery("select count(*) from CarBean");
System.out.println("row count = " + q.getSingleResult().toString());
return Integer.parseInt(q.getSingleResult().toString());
}
public List getPagedList(int startRow, int pageSize)
{
String sql = "from CarBean model order by model.id desc";
Query query = EntityManagerHelper.createQuery(sql);
query.setFirstResult(startRow);
query.setMaxResults(pageSize);
List list = query.getResultList();
System.out.println("current row count = " + list.size());
return list;
}
---------------------------------------------------------
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posted on 2008-10-29 10:58
TiGERTiAN 阅读(2835)
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