分类： Java
2008-04-03 11:33:57
使用一个页面控制类，它记录页面信息，如上页，下页，当前页等。在查询的Action中，将这个控制类和查询条件一起传递给数据库访问bean，然后将这两个参数保存在用户session中。在分页控制Action中，利用接收到的分页参数调用数据库访问的bean.
2,实现
(1)分页控制类
/* @author nick
* Created on 2004-3-18
* file name:PageController.java
*
*
*/
package com.tower.util;
/**
* @author nick
* 2004-3-18
* 用来进行翻页控制
*
*/
public class PageController {
int totalRowsAmount; //总行数
boolean rowsAmountSet; //是否设置过totalRowsAmount
int pageSize=2; //每页行数
int currentPage=1; //当前页码
int nextPage;
int previousPage;
int totalPages; //总页数
boolean hasNext; //是否有下一页
boolean hasPrevious; //是否有前一页
String description;
int pageStartRow;
int pageEndRow;
public PageController(int totalRows){
setTotalRowsAmount(totalRows);
}
public PageController(){}
/**
* @param i
* 设定总行数
*/
public void setTotalRowsAmount(int i) {
if(!this.rowsAmountSet){
totalRowsAmount = i;
totalPages=totalRowsAmount/pageSize+1;
setCurrentPage(1);
this.rowsAmountSet=true;
}
}
/**
* @param i
*
* 当前页
*
*/
public void setCurrentPage(int i) {
currentPage = i;
nextPage=currentPage+1;
previousPage=currentPage-1;
//计算当前页开始行和结束行
if(currentPage*pageSize
pageEndRow=currentPage*pageSize;
pageStartRow=pageEndRow-pageSize+1;
}else{
pageEndRow=totalRowsAmount;
pageStartRow=pageSize*(totalPages-1)+1;
}
//是否存在前页和后页
if (nextPage>totalPages){
hasNext=false;
}else{
hasNext=true;
}
if(previousPage==0){
hasPrevious=false;
}else{
hasPrevious=true;
};
System.out.println(this.description());
}
/**
* @return
*/
public int getCurrentPage() {
return currentPage;
}
/**
* @return
*/
public boolean isHasNext() {
return hasNext;
}
/**
* @return
*/
public boolean isHasPrevious() {
return hasPrevious;
}
/**
* @return
*/
public int getNextPage() {
return nextPage;
}
/**
* @return
*/
public int getPageSize() {
return pageSize;
}
/**
* @return
*/
public int getPreviousPage() {
return previousPage;
}
/**
* @return
*/
public int getTotalPages() {
return totalPages;
}
/**
* @return
*/
public int getTotalRowsAmount() {
return totalRowsAmount;
}
/**
* @param b
*/
public void setHasNext(boolean b) {
hasNext = b;
}
/**
* @param b
*/
public void setHasPrevious(boolean b) {
hasPrevious = b;
}
/**
* @param i
*/
public void setNextPage(int i) {
nextPage = i;
}
/**
* @param i
*/
public void setPageSize(int i) {
pageSize = i;
}
/**
* @param i
*/
public void setPreviousPage(int i) {
previousPage = i;
}
/**
* @param i
*/
public void setTotalPages(int i) {
totalPages = i;
}
/**
* @return
*/
public int getPageEndRow() {
return pageEndRow;
}
/**
* @return
*/
public int getPageStartRow() {
return pageStartRow;
}
public String getDescription(){
String description="Total:"+this.getTotalRowsAmount()+
" items "+this.getTotalPages() +" pages";
// this.currentPage+" Previous "+this.hasPrevious +
// " Next:"+this.hasNext+
// " start row:"+this.pageStartRow+
// " end row:"+this.pageEndRow;
return description;
}
public String description(){
String description="Total:"+this.getTotalRowsAmount()+
" items "+this.getTotalPages() +" pages,Current page:"+
this.currentPage+" Previous "+this.hasPrevious +
" Next:"+this.hasNext+
" start row:"+this.pageStartRow+
" end row:"+this.pageEndRow;
return description;
}
public static void main(String args[]){
PageController pc=new PageController(3);
System.out.println(pc.getDescription());
// pc.setCurrentPage(2);
// System.out.println(pc.description());
// pc.setCurrentPage(3);
// System.out.println(pc.description());
}
}
（2）查询Action的代码片断
public ActionForward execute(
ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response)
throws Exception {
Base queryForm= (Base) form;
if(!queryForm.getName().equals("")){
PageController pc=new PageController();
EmployeeBase service=new EmployeeBase();
ArrayList result=(ArrayList)service.search(queryForm,pc);
HttpSession session=request.getSession();
session.setAttribute("queryForm",queryForm);
session.setAttribute("pageController",service.getPageController());
request.setAttribute("queryResult",result);
request.setAttribute("pageController",service.getPageController());
return mapping.findForward("haveResult");
}else{
return mapping.findForward("noResult");
}
}
（3），翻页Action的代码片断
public ActionForward execute(
ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response)
throws Exception {
//读取翻页参数
TurnPageForm turnPageForm=(TurnPageForm)form;
//从PageController中取出查询信息，并使用bean提供的调用接口处理结果
HttpSession session=request.getSession();
PageController pc=(PageController)session.getAttribute("pageController");
Base queryForm=(Base)session.getAttribute("queryForm");
pc.setCurrentPage(turnPageForm.getViewPage());
EmployeeBase service=new EmployeeBase();
ArrayList result=(ArrayList)service.search(queryForm,pc);
//根据参数将数据写入 request
request.removeAttribute("queryResult");
request.removeAttribute("pageController");
request.setAttribute("queryResult",result);
request.setAttribute("pageController",pc);
//forward 到显示页面
return mapping.findForward("haveResult");
}
（4）数据库访问bean中的片断
public Collection search(Base base, PageController pc)
throws SQLException {
ArrayList emps = new ArrayList();
ResultSet rs = getSearchResult(base);
rs.absolute(-1);
pc.setTotalRowsAmount(rs.getRow());
setPageController(pc);
if (rs.getRow() > 0) {
rs.absolute(pc.getPageStartRow());
do {
System.out.println("in loop" + rs.getRow());
Base b = new Base();
b.setName(rs.getString("Name"));
b.setIdCard(rs.getString("IDCard"));
System.out.println("From db:" + rs.getString("IDCard"));
emps.add(b);
if (!rs.next()) {
break;
}
} while (rs.getRow() < (pc.getPageEndRow() + 1));
}
return emps;
}
(5)在jsp中，翻页部分的代码片断
<bean:write name="pageController" property="description"/>
<logic:equal name="pageController" property="hasPrevious" value="true">
Previous
logic:equal>
<logic:equal name="pageController" property="hasNext" value="true">
Next
logic:equal>
这样一来，翻页的功能可以以你喜欢的方式表现给client
