我想实现这个例子这是到目前为止的代码：
import java.io.Serializable;
import java.math.BigDecimal;
import javax.enterprise.context.SessionScoped;
// or import javax.faces.bean.SessionScoped;
import javax.inject.Named;
/* include SQL Packages */
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.annotation.PostConstruct;
import javax.sql.DataSource;
import javax.annotation.Resource;
import javax.faces.component.UICommand;
import javax.faces.context.FacesContext;
import javax.inject.Inject;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
// or import javax.faces.bean.ManagedBean;
import javax.faces.event.ActionEvent;
import org.glassfish.osgicdi.OSGiService;
//http://balusc.blogspot.com/2008/10/effective-datatable-paging-and-sorting.html
@Named("SessionsController")
@SessionScoped
public class Sessions implements Serializable {
/* Call the Oracle JDBC Connection driver */
@Resource(name = "jdbc/Oracle")
private DataSource ds;
// DAO.
private static ActiveSessionsDAO dao = DAOFactory.getInstance("javabase").getActiveSessionsDAO();
// Data.
private List<ActiveSessions> dataList;
private int totalRows;
// Paging.
private int firstRow;
private int rowsPerPage;
private int totalPages;
private int pageRange;
private Integer[] pages;
private int currentPage;
// Sorting.
private String sortField;
private boolean sortAscending;
// Constants ----------------------------------------------------------------------------------
private static final String SQL_LIST_BY_ORDER_AND_LIMIT =
"SELECT * FROM ACTIVESESSIONSLOG ORDER BY %s %s LIMIT ?, ?";
private static final String SQL_COUNT =
"SELECT count(*) FROM ACTIVESESSIONSLOG";
private static class DAOFactory {
public DAOFactory() {
}
}
private static class ActiveSessions {
public ActiveSessions() {
}
private ActiveSessions(long aLong, String string, Integer integer) {
throw new UnsupportedOperationException("Not yet implemented");
}
}
// Properties ---------------------------------------------------------------------------------
private DAOFactory daoFactory;
// Constructors -------------------------------------------------------------------------------
Sessions(DAOFactory daoFactory) {
this.daoFactory = daoFactory;
// Set default values somehow (properties files?).
rowsPerPage = 10; // Default rows per page (max amount of rows to be displayed at once).
pageRange = 10; // Default page range (max amount of page links to be displayed at once).
sortField = "ASESSIONID"; // Default sort field.
sortAscending = true; // Default sort direction.
}
// Paging actions -----------------------------------------------------------------------------
public void pageFirst() {
page(0);
}
public void pageNext() {
page(firstRow + rowsPerPage);
}
public void pagePrevious() {
page(firstRow - rowsPerPage);
}
public void pageLast() {
page(totalRows - ((totalRows % rowsPerPage != 0) ? totalRows % rowsPerPage : rowsPerPage));
}
public void page(ActionEvent event) {
page(((Integer) ((UICommand) event.getComponent()).getValue() - 1) * rowsPerPage);
}
private void page(int firstRow) {
this.firstRow = firstRow;
loadDataList(); // Load requested page.
}
// Sorting actions ----------------------------------------------------------------------------
public void sort(ActionEvent event) {
String sortFieldAttribute = (String) event.getComponent().getAttributes().get("sortField");
// If the same field is sorted, then reverse order, else sort the new field ascending.
if (sortField.equals(sortFieldAttribute)) {
sortAscending = !sortAscending;
} else {
sortField = sortFieldAttribute;
sortAscending = true;
}
pageFirst(); // Go to first page and load requested page.
}
// Loaders ------------------------------------------------------------------------------------
private void loadDataList() {
// Load list and totalCount.
try {
dataList = dao.list(firstRow, rowsPerPage, sortField, sortAscending);
totalRows = dao.count();
} catch (Exception e) {
throw new RuntimeException(e); // Handle it yourself.
}
// Set currentPage, totalPages and pages.
currentPage = (totalRows / rowsPerPage) - ((totalRows - firstRow) / rowsPerPage) + 1;
totalPages = (totalRows / rowsPerPage) + ((totalRows % rowsPerPage != 0) ? 1 : 0);
int pagesLength = Math.min(pageRange, totalPages);
pages = new Integer[pagesLength];
// firstPage must be greater than 0 and lesser than totalPages-pageLength.
int firstPage = Math.min(Math.max(0, currentPage - (pageRange / 2)), totalPages - pagesLength);
// Create pages (page numbers for page links).
for (int i = 0; i < pagesLength; i++) {
pages[i] = ++firstPage;
}
}
// Getters ------------------------------------------------------------------------------------
public List<ActiveSessions> getDataList() {
if (dataList == null) {
loadDataList(); // Preload page for the 1st view.
}
return dataList;
}
public int getTotalRows() {
return totalRows;
}
public int getFirstRow() {
return firstRow;
}
public int getRowsPerPage() {
return rowsPerPage;
}
public Integer[] getPages() {
return pages;
}
public int getCurrentPage() {
return currentPage;
}
public int getTotalPages() {
return totalPages;
}
// Setters ------------------------------------------------------------------------------------
public void setRowsPerPage(int rowsPerPage) {
this.rowsPerPage = rowsPerPage;
}
// Actions ------------------------------------------------------------------------------------
/**
* Returns list of ActiveSessions items starting at the given first index with the given row count,
* sorted by the given sort field and sort order.
* @param firstRow First index of rows to be returned.
* @param rowCount Amount of rows to be returned.
* @param sortField Field to sort the data on.
* @param sortAscending Whether to sort data ascending or not.
* @return list of ActiveSessions items starting at the given first index with the given row count,
* sorted by the given sort field and sort order.
* @throws DAOException If something fails at DAO level.
*/
public List<ActiveSessions> list(int firstRow, int rowCount, String sortField, boolean sortAscending)
throws Exception {
Object[] values = {firstRow, rowCount};
if (ds == null) {
throw new SQLException();
}
String sortDirection = sortAscending ? "ASC" : "DESC";
String sql = String.format(SQL_LIST_BY_ORDER_AND_LIMIT, sortField, sortDirection);
Connection conn = ds.getConnection();
PreparedStatement preparedStatement = null;
ResultSet resultSet = null;
List<ActiveSessions> dataList = new ArrayList<ActiveSessions>();
try {
conn.setAutoCommit(false);
boolean committed = false;
// connection = daoFactory.getConnection();
preparedStatement = conn.prepareStatement(sql);
resultSet = preparedStatement.executeQuery();
while (resultSet.next()) {
dataList.add(mapActiveSessions(resultSet));
}
} catch (SQLException e) {
throw new Exception(e);
} finally {
conn.close();
}
return dataList;
}
/**
* Returns total amount of rows in table.
* @return Total amount of rows in table.
* @throws DAOException If something fails at DAO level.
*/
public int count() throws Exception {
// Connection connection = null;
PreparedStatement preparedStatement = null;
ResultSet resultSet = null;
int count = 0;
try {
// connection = daoFactory.getConnection();
Connection conn = ds.getConnection();
preparedStatement = conn.prepareStatement(SQL_COUNT);
resultSet = preparedStatement.executeQuery();
if (resultSet.next()) {
count = resultSet.getInt(1);
}
} catch (SQLException e) {
throw new Exception(e);
} finally {
//close the connection
}
return count;
}
/**
* Map the current row of the given ResultSet to ActiveSessions.
* @param resultSet The ResultSet of which the current row is to be mapped to ActiveSessions.
* @return The mapped ActiveSessions from the current row of the given ResultSet.
* @throws SQLException If something fails at database level.
*/
private static ActiveSessions mapActiveSessions(ResultSet resultSet) throws SQLException {
return new ActiveSessions(
resultSet.getLong("ASESSIONID"),
resultSet.getString("USERID"),
resultSet.getObject("value") != null ? resultSet.getInt("value") : null);
/*
CREATE TABLE ACTIVESESSIONSLOG(
ASESSIONID VARCHAR2(30 ) NOT NULL,
USERID VARCHAR2(30 ),
ACTIVITYSTART TIMESTAMP(6),
ACTIVITYEND TIMESTAMP(6),
ACTIVITY CLOB
)
*/
}
}
我注意到 Netbeans 在这一行给了我一个错误：
private static ActiveSessionsDAO dao = DAOFactory.getInstance("javabase").getActiveSessionsDAO();
错误信息是：
cannot find symbol
symbol: class ActiveSessionsDAO
location: class com.DX_57.HM_57.Sessions
cannot find symbol
symbol: method getInstance(java.lang.String)
location: class com.DX_57.HM_57.Sessions.DAOFactory
我必须导入哪些依赖项？我可以简化代码并仅使用简单的 JDBC 连接从数据库中获取数据吗？
最好的祝愿