關於jsp+servlet MVC模式中的分頁操作

     我是一名大二的計科專業學生，感覺課堂上學的不夠，所以自學了jsp+servlet，跟着視頻做網上商城和論壇的項目，用的是mvc模式，這當中都涉及到了分頁操作，我看完后覺得比較好的是一種是這樣的：

先創建JavaBean

import java.util.ArrayList;

public class PageBean {
    private int pageNow;//第幾頁
    private int pageSize;//每頁顯示幾個記錄
    private int pageCount;//總頁數
    private int rowCount;//總記錄數
    private ArrayList al;//該頁要顯示的記錄
    
    public PageBean() {
        
    }
    public int getPageNow() {
        return pageNow;
    }
    public void setPageNow(int pageNow) {
        this.pageNow = pageNow;
    }
    public int getPageSize() {
        return pageSize;
    }
    public void setPageSize(int pageSize) {
        this.pageSize = pageSize;
    }
    public int getPageCount() {
        return pageCount;
    }
    public void setPageCount(int pageCount) {
        this.pageCount = pageCount;
    }
    public int getRowCount() {
        return rowCount;
    }
    public void setRowCount(int rowCount) {
        this.rowCount = rowCount;
    }
    public ArrayList getAl() {
        return al;
    }
    public void setAl(ArrayList al) {
        this.al = al;
    }
    
}

然后是一個操作數據庫的工具類，其中進行分頁的方法是：

//我以對論壇中的帖子分頁為例，顯示pid=0的帖子並分頁，Article是帖子類
public static void getPageInfo(PageBean pb){
    int pageNow = pb.getPageNow();//獲得要顯示的頁數
    int pageSize = pb.getPageSize();//獲得每頁顯示的記錄數
    int rowCount = 0;
    int pageCount = 0;
    ArrayList al = new ArrayList();
    try {
        ct = getConnection();
        ps=ct.prepareStatement("select top "+pageSize
                +" * from article where  pid = 0 and id not in (select top "
                +pageSize*(pageNow-1)+" id from article where pid = 0) ");
        rs = ps.executeQuery();
        while (rs.next()){
            Article article= new Article();
            article.setId(rs.getInt(1));
            article.setPid(rs.getInt(2));
            article.setRootId(rs.getInt(3));
            article.setTitle(rs.getString(4));
            article.setCont(rs.getString(5));
            article.setPdate(rs.getTimestamp(6));
            article.setIsLeaf(rs.getInt(7));
            al.add(article);
        }
        pb.setAl(al);//賦值要顯示頁的記錄
        ps = ct.prepareStatement("select count(*) from article where pid = 0");
        rs = ps.executeQuery();
        if (rs.next()){
            rowCount = rs.getInt(1);//得到記錄總數
        }
        pageCount = (rowCount - 1) / pageSize + 1;//得到頁總數
        pb.setPageCount(pageCount);
        pb.setRowCount(rowCount);
    } catch (Exception e) {
        e.printStackTrace();
        throw new RuntimeException(e.getMessage());
    } finally {
        close(rs, ps, ct);
    }
}

在昨天晚上，我突然想到了另外一種思路：

//我換了另一種思路，就是先把pid=0的帖子都取出來，再取出其中要顯示頁的記錄封裝到ArrayList中
//上面一種是先把要顯示頁的記錄取出來，再把記錄封裝到ArrayList中
public static void getPageInfo(PageBean pb){
    int pageNow = pb.getPageNow();//獲得要顯示的頁數
    int pageSize = pb.getPageSize();//獲得每頁顯示的記錄數
    int rowCount = 0;
    int pageCount = 0;
    ArrayList al = new ArrayList();
    try {
        ct = getConnection();
        ps=ct.prepareStatement("select * from article pid = 0"); 
        rs = ps.executeQuery();
        int startPos = (pageNow - 1 ) * pageSize;
        int i = 0;
        while (rs.next()){
            if (i == startPos){
                for (int j = 0; j < pageSize; j++){
                    Article article= new Article();
                    article.setId(rs.getInt(1));
                    article.setPid(rs.getInt(2));
                    article.setRootId(rs.getInt(3));
                    article.setTitle(rs.getString(4));
                    article.setCont(rs.getString(5));
                    article.setPdate(rs.getTimestamp(6));
                    article.setIsLeaf(rs.getInt(7));
                    al.add(article);
                    if (!rs.next()){
                        break;
                    }
                }
                break;
            }
            i++;
        }
        pb.setAl(al);//賦值要顯示頁的記錄
        ps = ct.prepareStatement("select count(*) from article where pid = 0");
        rs = ps.executeQuery();
        if (rs.next()){
            rowCount = rs.getInt(1);//得到記錄總數
        }
        pageCount = (rowCount - 1) / pageSize + 1;//得到頁總數
        pb.setPageCount(pageCount);
        pb.setRowCount(rowCount);
    } catch (Exception e) {
        e.printStackTrace();
        throw new RuntimeException(e.getMessage());
    } finally {
        close(rs, ps, ct);
    }
}

使用舉例：

int pageNow = 1;
int pageSize = 4;
String pagenow = request.getParameter("pageNow");
if (pagenow != null){
    pageNow = Integer.parseInt(pagenow);
}
PageBean pb = new PageBean();
pb.setPageNow(pageNow);
pb.setPageSize(pageSize);
SqlHelper.getPageInfo(pb);
request.setAttribute("pagebean", pb);
request.getRequestDispatcher("/XXX.jsp").forward(request, response);

     上述就是我對分頁操作的一點想法，一種是先把pid=0的帖子都取出來，再取出其中要顯示頁的記錄封裝到ArrayList中，另一種是先把要顯示頁的記錄取出來，再把記錄封裝到ArrayList中。不知道實際開發中是怎么進行分頁操作的，這僅是我自學后的一點點思考，希望前輩們給我點意見。