sayingdao.java

一个非常简单的mvc留言板MVC框架是STRUTS框架的基础

package com.aptech.dao;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.List;

import com.aptech.bean.Saying;
import com.aptech.util.DatabaseTool;

public class SayingDAO {
	private DatabaseTool dt = DatabaseTool.getInstance();
	/**
	 * 分页查询留言
	 * 
	 * @param curpage
	 *            当前页
	 * @param pagesize
	 *            页大小
	 * @return 当前页的留言
	 */
	public List getSayingsByPage(int curpage, int pagesize) {
		MessageFormat mf = new  MessageFormat("select top {0} saying.*,users.uname  from saying inner join users on saying.uid = users.uid where sid not in(select top {1} sid from saying  inner join users  on saying.uid = users.uid	order by sid desc)order by sid desc");
		String sql = mf.format(new Object[]{
				pagesize,
				(curpage - 1) * pagesize
		});
		ResultSet rs = dt.select(sql);
		List list = null;
		Saying saying = null;
		if(rs != null){
			list = new ArrayList();
			try {
				while(rs.next()){
					saying = new Saying();
					saying.setSid(rs.getInt("sid"));
					saying.setStitle(rs.getString("stitle"));
					saying.setScontent(rs.getString("scontent"));
					saying.setSdatetime(rs.getString("sdatetime"));
					saying.setUid(rs.getInt("uid"));
					saying.setUname(rs.getString("uname"));
					
					list.add(saying);
				}
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
				list = null;
			}
		}
		return list;
	}

	/**
	 * 添加新留言
	 * 
	 * @param saying
	 *            Saying对象
	 * @return 如果留言成功,则返回真,否则返回假的.
	 */
	public boolean addSaying(Saying saying) {
		MessageFormat mf = new MessageFormat("insert into Saying(stitle, scontent, sdatetime, uid) values(''{0}'', ''{1}'', ''{2}'', {3})");
		String sql = mf.format(new Object[]{
				saying.getStitle(),
				saying.getScontent(),
				new java.util.Date().toLocaleString(),
				saying.getUid()
		});
		
		return dt.insertOrUpdateOrDelete(sql);
	}

	/**
	 * 删除指定留言
	 * 
	 * @param sid
	 *            留言ID
	 * @return 如果删除成功,返回真,否则返回假值
	 */
	public boolean deleteSaying(int sid) {
		return false;
	}

	/**
	 * 得到总的留言数量
	 * 
	 * @return
	 */
	public int getSize() {
		String sql = "select count(*) from Saying";
		ResultSet rs = dt.select(sql);
		try {
			rs.next();
			return rs.getInt(1);
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		return 0;
	}

	/**
	 * 得到总页数
	 * 
	 * @param pagesize
	 *            页大小
	 * @return 返回总页数
	 */
	public int getPageCount(int pagesize) {
		int total = this.getSize();
		if(total % pagesize == 0){
			return total / pagesize;
		}else{
			return total / pagesize + 1;
		}
	}
}