分页封装

PagesFactory:

/**
 * 分页工厂
 * 根据数据库类型选择分页对象
 * 
 * @author  hjxia
 * @version  [版本号, 2010-7-27]
 * @see  [相关类/方法]
 * @since  [产品/模块版本]
 */
public class PagesFactory
{
    public static final String DEFAULT_DB_TYPE = "oracle";
    
    /**
     * 私有构造器，不允许实例化
     */
    private PagesFactory()
    {
        
    }
    
    /**
     * 获取分页对象
     * 
     * @return SplitPageInfo
     * @see [类、类#方法、类#成员]
     */
    public static SplitPageInfo getSplitPageInfo()
    {
        SplitPageInfo page = null;
        
        if ("oracle" == DEFAULT_DB_TYPE)
        {
            page = new OraclePageInfo();
        }
        
        return page;
    }
}

SplitPageInfo:

/**
 * 分页基本对象
 * 如要实现相应数据库分页对象，继承此类
 * 
 * @author  hjxia
 * @version  [版本号, 2010-7-27]
 * @see  [相关类/方法]
 * @since  [产品/模块版本]
 */
public abstract class SplitPageInfo implements Serializable
{
    /**
     * 序列号
     */
    private static final long serialVersionUID = 1L;

    /** 开始记录数 */
    protected int beginNum = 0;
    
    /** 结束记录数 */
    protected int endNum;
    
    /** SQL语句 */
    private String strSQL = "";
    
    /** 分页查询的URL */
    private String queryURL;
    
    /** 排序字段名称 */
    private String orderName;
    
    /** 排序字段类型 */
    private String orderType;
    
    /** 记录总数 */
    private int totals;
    
    /** 每页显示记录数 */
    private int perPageNum;
    
    /** 总页数 */
    private int allPage;
    
    /** 当前页 */
    private int currPage;
    
    /**
     * 构造
     */
    public SplitPageInfo()
    {
    }
    
    /**
     * 获取分页SQL
     * 抽象方法，子类实现
     * @return String sql
     * @see [类、类#方法、类#成员]
     */
    public abstract String getSplitSql();
    
    /**
     * 计算开始和结束记录数
     * 
     * @see [类、类#方法、类#成员]
     */
    public void doPage()
    {
        // 计算总页数
        this.setAllPage((this.totals + this.perPageNum - 1) / this.perPageNum);
        
        if (currPage > allPage)
        {
            currPage = 1;
        }
        // 计算开始记录数
        this.beginNum = (this.getCurrPage() - 1) * this.perPageNum;
        // 计算结束记录数
        this.endNum = (beginNum + perPageNum) < totals ? beginNum + perPageNum : totals;
    }
    
    /**
     * 设置排序SQL
     * 
     * @param sql 原始sql
     * @see [类、类#方法、类#成员]
     */
    public void setOrderSql(String sql)
    {
        if (null != this.orderName && !"".equals(this.orderName))
        {
            sql += " order by " + this.orderName;
            sql += " " + this.orderType;
        }
        
        this.setStrSQL(sql);
    }
    
    /**
     * 获取查询总记录数的SQL
     * 
     * @return String 查询总记录数的SQL
     * @see [类、类#方法、类#成员]
     */
    public String getTotalSql()
    {
        StringBuffer stringBuffer = new StringBuffer();
        stringBuffer.append("select count(*) as recordCount from (");
        stringBuffer.append(this.strSQL);
        stringBuffer.append(") tableName");
        
        return stringBuffer.toString();
    }

    public int getBeginNum()
    {
        return beginNum;
    }

    public void setBeginNum(int beginNum)
    {
        this.beginNum = beginNum;
    }

    public int getEndNum()
    {
        return endNum;
    }

    public void setEndNum(int endNum)
    {
        this.endNum = endNum;
    }

    public String getStrSQL()
    {
        return strSQL;
    }

    public void setStrSQL(String strSQL)
    {
        this.strSQL = strSQL;
    }

    public String getQueryURL()
    {
        return queryURL;
    }

    public void setQueryURL(String queryURL)
    {
        this.queryURL = queryURL;
    }

    public String getOrderName()
    {
        return orderName;
    }

    public void setOrderName(String orderName)
    {
        this.orderName = orderName;
    }

    public String getOrderType()
    {
        return orderType;
    }

    public void setOrderType(String orderType)
    {
        this.orderType = orderType;
    }

    public int getTotals()
    {
        return totals;
    }

    public void setTotals(int totals)
    {
        this.totals = totals;
    }

    public int getPerPageNum()
    {
        return perPageNum;
    }

    public void setPerPageNum(int perPageNum)
    {
        this.perPageNum = perPageNum;
    }

    public int getAllPage()
    {
        return allPage;
    }

    public void setAllPage(int allPage)
    {
        if (allPage < 1)
        {
            allPage = 1;
        }
        
        this.allPage = allPage;
    }

    public int getCurrPage()
    {
        return currPage;
    }

    public void setCurrPage(int currPage)
    {
        if (currPage < 1)
        {
            currPage = 1;
        }
        
        this.currPage = currPage;
    }
}

OraclePageInfo:

/**
 * ORACLE分页对象,继承自SplitPageInfo
 * 
 * 
 * @author  hjxia
 * @version  [版本号, 2010-7-27]
 * @see  [相关类/方法]
 * @since  [产品/模块版本]
 */
public class OraclePageInfo extends SplitPageInfo
{
    /**
     * 获取分页SQL
     * @return
     */
    public String getSplitSql()
    {
        this.doPage();
        StringBuffer sqlBuffer = new StringBuffer();
        sqlBuffer.append("select * from (select t.*, rownum r_id from (");
        sqlBuffer.append(this.getStrSQL());
        sqlBuffer.append(") t where rownum <= ");
        sqlBuffer.append(endNum);
        sqlBuffer.append(") where r_id > ");
        sqlBuffer.append(beginNum);
        
        String str = sqlBuffer.toString();
        
        //记录日志
        
        return str;
    }
}