pagebean.java

一个java的分页程序

package page;

import java.sql.ResultSet;
import java.sql.*;
import db.DataBean;
import java.util.*;
import util.*;

public class PageBean
{
    private ResultSet rs;
    private int totalPage;
    private int page;
    private int pageSize;
    private int totalRow;
    private OperBean ob;

    public PageBean()
    {
    }

    //获取当前页数
    //注意：在jsp页面代码中调用该方法前应确保前面调用过getNextCurRow(ResultSet _rs, int _pageSize, int _page)方法，否则不能获得正确值
    public int getCurrentPage()
    {
        return this.page;
    }

    //获取总页数
    //注意：在jsp页面代码中调用该方法前应确保前面调用过getNextCurRow(ResultSet _rs, int _pageSize, int _page)方法，否则不能获得正确值
    public int getTotalPage()
    {
        return this.totalPage;
    }

    //获取总行数
    //注意：在jsp页面代码中调用该方法前应确保前面调用过getNextCurRow(ResultSet _rs, int _pageSize, int _page)方法，否则不能获得正确值
    public int getTotalRow()
    {
        return this.totalRow;
    }

    //从数据库得到每页显示的行数
    //如果没有则返回默认值：5行
    public int getPageSize()
    {
        DataBean db = new DataBean();
        ResultSet rsPageSize = db.select("column_value",
                "t_drawer where column_name='SIZE' and table_name='T_PAGE_SIZE'");
        try
        {
            if (rsPageSize.next())
            {
                this.pageSize = Integer.parseInt(rsPageSize.getString(
                        "column_value"));
            }
        }
        catch (Exception ex)
        {
            return 5;
        }
        finally
        {
            db.close();
        }

        return this.pageSize;
    }

    //移动记录集的指针指向要显示的行之前
    //同时该方法也为page、totalPage和totalRow变量赋值
    public void getNextCurRow(ResultSet _rs, int _pageSize, int _page)
    {
        this.rs = _rs;
        this.pageSize = _pageSize;
        this.page = _page;

        this.pageSize = this.pageSize <= 0 ? 5 : this.pageSize;
        this.page = this.page <= 0 ? 1 : this.page;

        //获取总行数
        try
        {
            rs.last();
            this.totalRow = rs.getRow();
        }
        catch (SQLException ex)
        {
            ex.printStackTrace();
        }

        //计算总页数
        if (this.totalRow < this.pageSize)//总行数小于每页行数时
        {
            this.totalPage = 1;
        }
        else if (this.totalRow % this.pageSize == 0)//总行数大于每页行数且总行数为每页行数的倍数时
        {
            this.totalPage = this.totalRow / this.pageSize;
        }
        else//总行数大于每页行数且总行数不为每页行数的倍数时
        {
            this.totalPage = this.totalRow / this.pageSize + 1;
        }

        if (this.page > this.totalPage)//当前页面不能大于总页数
        {
            this.page = this.totalPage;
        }

        try
        {
            if ( (this.page - 1) * this.pageSize == 0)
            {
                rs.beforeFirst();
            }
            else
            {
                rs.absolute( (this.page - 1) * this.pageSize);
            }
        }
        catch (SQLException ex1)
        {
            ex1.printStackTrace();
        }
    }

    /**
     * 查询数据库，并返回封装要显示页面的数据的List
     * @param entity String为sql语句中select与from之间的内容
     * @param prec String为sql语句中from之后的内容
     * 上述参数示范：select entity from prec
     * @param _pageSize int每页要显示的行数
     * @param _page String要显示的页面的页码
     * @return ArrayList是封装要显示页面的数据<br/>
     * jsp页面中调用取值代码示范：<br/>
     * PageBean pb=new PageBean();<br/>
     * String entity="column_name1,column_name2";<br/>
     * String prec="table";<br/>
     * ArrayList list=pb.getCurPageRow(entity,prec,5,"2");<br/>
     * if(list==null){list=Collections.EMPTY_LIST;}//注意：此句在jdk1.5后可用<br/>
     * //如为jdk1.5以下则改为：if(list==null){list=new ArrayList();}<br/>
     * HashMap map;<br/>
     * for(int i=0;i&lt;list.size();i++)<br/>
     * {<br/>
     *   map=(HashMap)list.get(i);<br/>
     *   out.print(map.get("column_name1"));//注意column_name为列名，一律小写字母<br/>
     *   out.print(map.get("column_name2")); <br/>
     * }

     */
    public ArrayList getCurPageRow(String entity, String prec, int _pageSize,
                                   String _page)
    {
        ob = new OperBean();
        ArrayList list = ob.select(entity, prec);
        this.pageSize = _pageSize <= 0 ? 5 : _pageSize;
        if (_page != null)
        {
            try
            {
                this.page = Integer.parseInt(_page);
                this.page = this.page <= 0 ? 1 : this.page;
            }
            catch (Exception e)
            {
                e.printStackTrace();
                this.page = 1;
            }
        }
        else
        {
            this.page = 1;
        }

        if (list == null)
        {
            return null;
        }
        else
        {
            this.totalRow = list.size(); //得到总行数
            list = null;

            //计算总页数
            if (this.totalRow < this.pageSize) //总行数小于每页行数时
            {
                this.totalPage = 1;
            }
            else if (this.totalRow % this.pageSize == 0) //总行数大于每页行数且总行数为每页行数的倍数时
            {
                this.totalPage = this.totalRow / this.pageSize;
            }
            else //总行数大于每页行数且总行数不为每页行数的倍数时
            {
                this.totalPage = this.totalRow / this.pageSize + 1;
            }

            if (this.page > this.totalPage) //当前页面不能大于总页数
            {
                this.page = this.totalPage;
            }

            return ob.select(entity, prec,
                             Integer.toString( (this.page - 1) * this.pageSize + 1),
                             Integer.toString(this.pageSize));
        }
    }

    /**
     *生成翻页页脚，调用该方法前一定要先调用getCurPageRow（）方法
     * @param queryStr String翻页时需要跟的查询字符串<br/>
     * 查询字符串示例：<br/>
     * query1=query1&query2=query2&query3=query3
     * @return String返回包含<table>的html代码。返回的table宽度为100%，要用jsp页面的table限制显示宽度<br/>
     * 调用示例：<br/>
     * &lt;table width='600'&gt;<br/>
     *   &lt;tr&gt;<br/>
     *      &lt;td&gt;<br/>
     *         out.print(pb.getFooter("query1=query1&query2=query2&query3=query3"))//pb对象为前面调用pb.getCurPageRow()时的对象;<br/>
     *      &lt;/td&gt;<br/>
     *   &lt;/tr&gt;<br/>
     * &lt;/table&gt;<br/>
     */
    public String getFooter(String queryStr)
    {
        try
        {
            String[] query = queryStr.split("&");
            HashMap map = new HashMap();
            for (int i = 0; i < query.length; i++)
            {
                String[] temp = query[i].split("=");
                if(temp.length<2)
                {
                    map.put(temp[0],"");
                }
                else
                {
                    map.put(temp[0], temp[1]);
                }
            }
            Iterator iter = map.keySet().iterator();
            String str =
                    "<table width='100%'><form action='' method='post' name='pageForm'>";
            str += "<tr><td align='center'>";
            if (this.getTotalPage() > 1)
            {
                str += "<a href='' onclick='document.pageForm.page.value="+1+";document.pageForm.submit();return false;'>首 页</a>&nbsp;&nbsp;";
                str += "<a href='' onclick='document.pageForm.page.value="+(this.getCurrentPage() - 1)+";document.pageForm.submit();return false;'>上一页</a>&nbsp;&nbsp;";
                str +="<a href='' onclick='document.pageForm.page.value="+(this.getCurrentPage() + 1)+";document.pageForm.submit();return false;'>下一页</a>&nbsp;&nbsp;";
                str +="<a href='' onclick='document.pageForm.page.value="+this.getTotalPage()+";document.pageForm.submit();return false;'>尾 页</a>&nbsp;&nbsp;&nbsp;&nbsp;";
            }
            else
            {
                str +=
                        "首 页&nbsp;&nbsp;上一页&nbsp;&nbsp;下一页&nbsp;&nbsp;尾 页&nbsp;&nbsp;&nbsp;&nbsp;";
            }
            str += "第" + this.getCurrentPage() + "页&nbsp;共" + this.getTotalPage()
                    + "页&nbsp;总记录数：" + this.getTotalRow();
            str += "&nbsp;&nbsp;&nbsp;&nbsp;<input type='submit' value='G0'/>&nbsp;";
            str += "<input type='text' name='page' size='2'/>页";
            while (iter.hasNext())
            {
                String tempStr = iter.next().toString();
                str += "<input type='hidden' name='"+tempStr+"' value='"+map.get(tempStr)+"'/>";
            }
            str += "</td></tr></form></table>";
            return str;
        }
        catch(Exception e)
        {
            e.printStackTrace();
            return "页脚生成错误！";
        }
    }
}