在struts中分頁的一種實現

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-- 作者：未知
-- 發佈日期： 2005-04-28

在struts中分頁的一種實現

我的項目中的分頁功能
1，思路

使用一個頁面控制類，它記錄頁面信息，如上頁，下頁，當前頁等。在查詢的Action中，將這個控制類和查詢條件一起傳遞給數據庫訪問bean，然後將這兩個參數保存在用戶session中。在分頁控制Action中，利用接收到的分頁參數調用數據庫訪問的bean.

2,實現

(1)分頁控制類
/* @author nick
* Created on 2004-3-18
* file name:PageController.java
*
*
*/
package com.tower.util;

/**
* @author nick
* 2004-3-18
* 用來進行翻頁控制
*
*/
public class PageController {
int totalRowsAmount; //總行數
boolean rowsAmountSet; //是否設置過totalRowsAmount
int pageSize=2; //每頁行數
int currentPage=1; //當前頁碼
int nextPage;
int previousPage;
int totalPages; //總頁數
boolean hasNext; //是否有下一頁
boolean hasPrevious; //是否有前一頁
String description;
int pageStartRow;
int pageEndRow;

public PageController(int totalRows){
setTotalRowsAmount(totalRows);
}
public PageController(){}

/**
* @param i
* 設定總行數
*/
public void setTotalRowsAmount(int i) {
if(!this.rowsAmountSet){
totalRowsAmount = i;
totalPages=totalRowsAmount/pageSize+1;
setCurrentPage(1);
this.rowsAmountSet=true;
}

}

/**
* @param i
*
* 當前頁
*
*/
public void setCurrentPage(int i) {
currentPage = i;
nextPage=currentPage+1;
previousPage=currentPage-1;
//計算當前頁開始行和結束行
if(currentPage*pageSize<totalRowsAmount){
pageEndRow=currentPage*pageSize;
pageStartRow=pageEndRow-pageSize+1;

}else{
pageEndRow=totalRowsAmount;
pageStartRow=pageSize*(totalPages-1)+1;
}

//是否存在前頁和後頁

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）查詢Action的代碼片斷

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），翻頁Action的代碼片斷

public ActionForward execute(
ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response)
throws Exception {

//讀取翻頁參數

TurnPageForm turnPageForm=(TurnPageForm)form;

//從PageController中取出查詢信息，並使用bean提供的調用接口處理結果

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);

//根據參數將數據寫入 request

request.removeAttribute("queryResult");
request.removeAttribute("pageController");
request.setAttribute("queryResult",result);
request.setAttribute("pageController",pc);

//forward 到顯示頁面

return mapping.findForward("haveResult");

}

（4）數據庫訪問bean中的片斷

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，翻頁部分的代碼片斷

<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>

這樣一來，翻頁的功能可以以你喜歡的方式表現給client

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