1 设置跳转
<logic:equal name="page" property="hasPreviousPage" value="true">
<a href="list.do?currentPage=<bean:write name="page" property="previousPage"/>">上一页</a>
</logic:equal>
<logic:equal name="page" property="hasNextPage" value="true">
<a href="list.do?currentPage=<bean:write name="page" property="nextPage"/>">下一页</a>
</logic:equal>
2 在Form中设置private String currentPage ;
3进入action,在action中，页面信息都是在pagebean得到的，根据页面信息，进行分页操作
public ActionForward execute(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response) {
ListForm listForm = (ListForm) form;// TODO Auto-generated method stub
HttpSession session = request.getSession();
PageBean pb ;
NewsDao newsdao = new NewsDao();
List list = new ArrayList();
String currentPage = listForm.getCurrentPage();
if(currentPage == null){
int totalRows = newsdao.getTotalRows();
System.out.println(totalRows);
pb = new PageBean(totalRows,1);
session.removeAttribute("page");
System.out.println("当前页面"+String.valueOf(pb.getPageStartRow()));
list = newsdao.getPageQueryDate(String.valueOf(pb.getPageStartRow()),String.valueOf(pb.getPageRecorders()));
System.out.println("进入action11");
}
else{
int totalRows = newsdao.getTotalRows();
pb = new PageBean(totalRows,Integer.parseInt(currentPage));
System.out.println("当前页面"+String.valueOf(pb.getPageStartRow()));
list = newsdao.getPageQueryDate(String.valueOf(pb.getPageStartRow()), String.valueOf(pb.getPageRecorders()));
session.setAttribute("page",pb);
request.setAttribute("all", list);
return mapping.findForward("pageinfo");
}
}
在action中,会涉及到三个方法
(1)
查询到数据库中记录的跳数
public int getTotalRows() {
int totalRows = 0;
String sql = "select count(*) from Newsvo";
Connection conn = this.session.connection();
PreparedStatement pstmt;
try {
pstmt = conn.prepareStatement(sql);
ResultSet rs =pstmt.executeQuery();
if(rs.next()){
String id = (String) rs.getString(1);
totalRows = Integer.parseInt(id);
}
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return totalRows;
}
}
(2)
根据记录的条数,得到分页信息
public class PageBean {
private int currentPage = 1; // 当前页
private int totalPages = 0; // 总页数
private int pageRecorders = 5;// 每页5条数据
private int totalRows = 0; // 总数据数
private int pageStartRow = 0;// 每页的起始数
private int pageEndRow = 0; // 每页显示数据的终止数
private boolean hasNextPage = false; // 是否有下一页
private boolean hasPreviousPage = false; // 是否有前一页
private int nextPage = 0;//下一页的页码
private int previousPage = 0;//上一页的页码
public PageBean(int totalRows,int currentPage) {
this.totalRows = totalRows;
this.currentPage = currentPage;
if(currentPage < 2)
hasPreviousPage = false;
else
hasPreviousPage = true;
if ((totalRows % pageRecorders) == 0) {
totalPages = totalRows / pageRecorders;
} else {
totalPages = totalRows / pageRecorders + 1;
}
if (currentPage < totalPages) {
hasNextPage = true;
nextPage = currentPage + 1;
pageStartRow = (currentPage - 1)*pageRecorders;
this.pageEndRow = pageStartRow + pageRecorders;
} else if(currentPage == totalPages){
pageStartRow = (currentPage - 1)*pageRecorders;
this.pageEndRow = totalRows;
hasNextPage = false;
nextPage = currentPage;
}
if(currentPage < 2){
previousPage = currentPage;
hasPreviousPage = false;
}else if(currentPage > 1){
previousPage = currentPage-1;
hasPreviousPage = true;
}
}
public int getCurrentPage() {
return currentPage;
}
public void setCurrentPage(int currentPage) {
this.currentPage = currentPage;
}
public boolean isHasNextPage() {
return hasNextPage;
}
public void setHasNextPage(boolean hasNextPage) {
this.hasNextPage = hasNextPage;
}
public boolean isHasPreviousPage() {
return hasPreviousPage;
}
public void setHasPreviousPage(boolean hasPreviousPage) {
this.hasPreviousPage = hasPreviousPage;
}
public int getNextPage() {
return nextPage;
}
public void setNextPage(int nextPage) {
this.nextPage = nextPage;
}
public int getPageEndRow() {
return pageEndRow;
}
public void setPageEndRow(int pageEndRow) {
this.pageEndRow = pageEndRow;
}
public int getPageRecorders() {
return pageRecorders;
}
public void setPageRecorders(int pageRecorders) {
this.pageRecorders = pageRecorders;
}
public int getPageStartRow() {
return pageStartRow;
}
public void setPageStartRow(int pageStartRow) {
this.pageStartRow = pageStartRow;
}
public int getPreviousPage() {
return previousPage;
}
public void setPreviousPage(int previousPage) {
this.previousPage = previousPage;
}
public int getTotalPages() {
return totalPages;
}
public void setTotalPages(int totalPages) {
this.totalPages = totalPages;
}
public int getTotalRows() {
return totalRows;
}
public void setTotalRows(int totalRows) {
this.totalRows = totalRows;
}
}
(3)根据分页信息，把数据查询出来
public List<Newsvo> getPageQueryDate(String startRow,String num){
List list = new ArrayList();
System.out.println("进入查询");
String sql="select * from Newsvo limit "+startRow+","+num;
Connection conn = this.session.connection();
PreparedStatement pstmt ;
try {
pstmt = conn.prepareStatement(sql);
ResultSet rs = pstmt.executeQuery();
while(rs.next()){
Newsvo news = new Newsvo();
news.setId(rs.getInt("id"));
news.setUrl(rs.getString("url"));
//news.setUrl(newsvo.getUrl());
news.setTitle(rs.getString("title"));
System.out.println(rs.getString("title"));
list.add(news);
} } catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return list;
}
错误：dao中，
while(rs.next()){
Newsvo news = new Newsvo();
news.setId(rs.getInt("id"));
news.setUrl(rs.getString("url"));
//news.setUrl(newsvo.getUrl());
news.setTitle(rs.getString("title"));
System.out.println(rs.getString("title"));
list.add(news); }
我把vo的定义，放在while以外，发生了查询的是同一条数据。
