实现分页功能 web

首先新建实现分页工具类：

package com.servlet.product.util;

public class DividePageUtil {

    private int pageSize;// 表示显示的条数
    private int recordCount;// 表示记录的总条数
    private int currentPage;// 表示当前页

    public DividePageUtil(int pageSize, int recordCount, int currentPage) {
        // TODO Auto-generated constructor stub
        this.pageSize = pageSize;
        this.recordCount = recordCount;
        setCurrentPage(currentPage);
    }

    public DividePageUtil(int pageSize, int recordCount) {
        // TODO Auto-generated constructor stub
        this(pageSize, recordCount, 1);
    }

    // 获得总页数
    public int getPageCount() {
        int size = recordCount / pageSize;
        int mod = recordCount % pageSize;
        if (mod != 0) {
            size++;
        }
        return recordCount == 0 ? 1 : size;
    }

    public int getFromIndex() {
        return (currentPage - 1) * pageSize;
    }

    public int getToIndex() {
        return pageSize;
    }

    public int getCurrentPage() {
        return currentPage;
    }

    public void setCurrentPage(int currentPage) {
        int validPage = currentPage <= 0 ? 1 : currentPage;
        validPage = validPage > getPageCount() ? getPageCount() : validPage;
        this.currentPage = validPage;
    }

    public int getPageSize() {
        return pageSize;
    }

    public void setPageSize(int pageSize) {
        this.pageSize = pageSize;
    }

    public int getRecordCount() {
        return recordCount;
    }

    public void setRecordCount(int recordCount) {
        this.recordCount = recordCount;
    }
}

在数据访问类中添加一个方法 来获得数据的总条数

public int getItemCount() {
        int result = 0;
        Map<String, Object> map = null;
        String sql = " select count(*) mycount from product ";
        try {
            conn.getConnect();
            map = conn.queryBySimpleResult(sql, null);
            result = Integer.parseInt(map.get("mycount").toString());

        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            conn.releaseConnect();
        }

        return result;
    }

 在数据处理类中来处理分类：

        // 获得数据总条数
        int recordCount = service.getItemCount();
        // 当前页面 初始化为 1
        int currentPage = 1;
        // 获得当前页面
        String pageNum = request.getParameter("pageNum");
        if (pageNum != null) {
            currentPage = Integer.parseInt(pageNum);
        }
        
        DividePageUtil util = new DividePageUtil(5, recordCount, currentPage);
        //开始的条数
        int start = util.getFromIndex();
        //结束的条数
        int end = util.getToIndex();
        String proname = (String) request.getParameter("proname");
        List<Map<String, Object>> list = service.listProduct(proname, start,
                end);
　　　　 request.setAttribute("util", util);

在jsp页面中使用javaScript来做处理：

function firstPage(){
    var th=document.form1;
    th.action="<%=path %>/servlet/ProductAction?action_flag=list&pageNum=1";
    th.submit();
}
function forward(){
    var th=document.form1;
    th.action="<%=path %>/servlet/ProductAction?action_flag=list&pageNum=<%=util.getCurrentPage()-1%>";
    th.submit();
}
function next(){
    var th=document.form1;
    th.action="<%=path %>/servlet/ProductAction?action_flag=list&pageNum=<%=util.getCurrentPage()+1%>";
    th.submit();
}
function endPage(){
    var th=document.form1;
    th.action="<%=path %>/servlet/ProductAction?action_flag=list&pageNum=<%=util.getPageCount()%>";
    th.submit();
}
function onChange(currentPage){
    var th=document.form1;
    th.action="<%=path %>/servlet/ProductAction?action_flag=list&pageNum="+currentPage;
    th.submit();