在struts中分页的一种实现

我的项目中的分页功能

1， 思路

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<totalRowsAmount){

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">

<a href="turnPage.do?viewPage=<bean:write name="pageController" property="previousPage"/>" class="a02">

Previous

</a>

</logic:equal>

<logic:equal name="pageController" property="hasNext" value="true">

<a href="turnPage.do?viewPage=<bean:write name="pageController" property="nextPage"/>" class="a02">

Next

</a>

</logic:equal>

这样一来，翻页的功能可以以你喜欢的方式表现给client