newsdao.java

java web网络编程示例,原代码资源

package edu.liusong.dao;

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

import edu.liusong.common.DBConnect;
import edu.liusong.mo.News;
import edu.liusong.mo.User;

public class NewsDAO {
	private DBConnect conn;

	private ResultSet rs;

	/**
	 * 保存通知
	 * 
	 * @param news
	 * @return
	 */
	public int save(News news) {
		int i = 0;
		try {
			conn = new DBConnect();
			String sql="insert into news values(?,?,?,?)";
			String []values={String.valueOf(news.getNid()),news.getTitle(),news.getContent(),news.getAtime().toString()};
			i=conn.executeUpdate(sql, values);
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			if (conn != null) {
				try {
					conn.close();
				} catch (SQLException e) {
					e.printStackTrace();
				}
			}
		}
		return i;
	}

	/**
	 * 通过nid获得通知
	 * 
	 * @param id
	 * @return
	 */
	public News getById(long id) {
		News news = null;
		try {
			conn = new DBConnect();
			String sql = "select * from news where nid=" + id;
			rs = conn.executeQuery(sql, null);
			if (rs.next()) {
				news = new News();
				news.setNid(rs.getLong(1));
				news.setTitle(rs.getString(2));
				news.setContent(rs.getString(3));
				news.setAtime(rs.getTimestamp(4));
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			if (conn != null)
				try {
					conn.close();
				} catch (SQLException e) {
					e.printStackTrace();
				}
		}

		return news;
	}

	/**
	 * 返回最新的八条通知
	 * 
	 * @return list
	 */
	public List getTopNews() {
		List<News> list = new ArrayList<News>();
		try {
			conn = new DBConnect();
			String sql = "select * from news order by atime desc limit 0,8";
			rs = conn.executeQuery(sql, null);
			while (rs.next()) {
				News news = new News();
				news.setNid(rs.getLong(1));
				news.setTitle(rs.getString(2));
				news.setContent(rs.getString(3));
				news.setAtime(rs.getTimestamp(4));
				list.add(news);
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			if (conn != null) {
				try {
					conn.close();
				} catch (SQLException e) {
					e.printStackTrace();
				}
			}
		}
		return list;
	}

	/**
	 * 分页查询
	 * @param pageSize
	 * @param topage
	 * @return
	 */
	public List getByPage(int pageSize,int topage){
		List<News> list=new ArrayList<News>();
		int recordcount;
		int pagecount;
		try {
			conn=new DBConnect();
			String sql="select * from news  order by atime desc ";
			rs=conn.executeQuery(sql, null);
			rs.last();
			recordcount=rs.getRow();
			pagecount=(recordcount+pageSize-1)/pageSize;
			if(topage>pagecount)
				topage=pagecount;
			rs.absolute((topage-1)*pageSize+1);
			int j=0;
			while((j<pageSize)&&(!rs.isAfterLast())){
				News news=new News();
				news.setNid(rs.getLong(1));
				news.setTitle(rs.getString(2));
				news.setContent(rs.getString(3));
				news.setAtime(rs.getTimestamp(4));
				list.add(news);
				rs.next();
				j++;
			}
		} catch (Exception e) {
			e.printStackTrace();
		}finally{
			if(conn!=null){
				try {
					conn.close();
				} catch (SQLException e) {
					e.printStackTrace();
				}
			}
		}
		return list;
	}
	/**
	 * 根据nid删除记录
	 * @param id
	 */
	public void deleteById(String id){
		try {
			conn=new DBConnect();
			String sql="delete from news where nid=?";
			String[] values={id};
			conn.executeUpdate(sql, values);
		} catch (Exception e) {
			e.printStackTrace();
		}finally{
			if(conn!=null){
				try {
					conn.close();
				} catch (SQLException e) {
					e.printStackTrace();
				}
			}
		}
	}	
	
	
}