JSF+Spring+Hibernate 分页显示

package org.apache.myfaces.examples.listexample; import javax.faces.model.DataModel; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; public abstract class PagedListDataModel extends DataModel { private final Log log = LogFactory.getLog("PagedListDataModel"); 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) { log.info("默认rowCount:" + rowCount); rowCount = fetchRowCount(); log.info("初始化rowCount:" + rowCount); } 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 log.info("getPage：" + name + "创建page"); 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();// log.info("getRowData：创建page"); } int datasetSize = page.getDatasetSize(); int startRow = page.getStartRow(); int nRows = page.getData().size(); int endRow = startRow + nRows; //System.out.println("datasetSize:"+datasetSize); //System.out.println("startRow:"+startRow); //System.out.println("nRows:"+nRows); //System.out.println("endRow:"+endRow); boolean flag=rowIndex < startRow; //boolean flag1=rowIndex >= datasetSize; //System.out.println("rowIndex >= datasetSize:"+flag1); if (rowIndex >= datasetSize) { throw new IllegalArgumentException("Invalid rowIndex"); } if (rowIndex < startRow) { log.info("fetchPage：向前取数据,getRowData：创建page,rowIndex:" + rowIndex); page = fetchPage(rowIndex, pageSize); log.info("翻页之前rowCount:" + rowCount); rowCount = page.getDatasetSize();// log.info("翻页之后rowCount:" + rowCount); startRow = page.getStartRow(); } else if (rowIndex >= endRow) { log.info("fetchPage：向后取数据,getRowData：创建page,rowIndex:" + rowIndex); page = fetchPage(rowIndex, pageSize); log.info("翻页之前rowCount:" + rowCount); rowCount = page.getDatasetSize();// log.info("翻页之后rowCount:" + rowCount); 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(); }