news_system,实现简单网页+java后台+数据库对标题和内容进行增删改查

package dao.imp; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.util.ArrayList; import java.util.List; import shujuku.Shujuku; import dao.NewsDao; import entity.news; public class NewsDaoImp implements NewsDao{ Connection con=null; PreparedStatement ps=null; ResultSet rs=null; /*******添加新闻内容********************************************************************/ public int addnews(news n) { int a=0; try { con=Shujuku.conn(); String sql="insert into news values(?,?,?,?)"; ps=con.prepareStatement(sql); ps.setString(1, n.getTitle()); ps.setString(2, n.getContain()); ps.setString(3, n.getAutor()); ps.setInt(4, n.getTypeid()); a=ps.executeUpdate(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } return a; } /*******查看新闻内容********************************************************************/ public List<news> selectall(news n) { List<news> list=new ArrayList<news>(); try { con=Shujuku.conn(); //两个关联，通过ID查到名字 String sql="select n.id,n.title,n.contain,n.autor,ts.typename " + "from news as n " + "inner join typesname as ts " + "on n.typeid=ts.id"; ps=con.prepareStatement(sql); rs=ps.executeQuery(); while(rs.next()){ //另一个构造函数 news ty=new news( rs.getInt("id"),rs.getString("title"), rs.getString("contain"),rs.getString("autor"), rs.getString("typename"));//新建构造函数的对象/////注意是逗号 list.add(ty); } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } return list; } /*******删除新闻内容********************************************************************/ public int delete(news n) { int a=0; try { con=Shujuku.conn(); String sql="delete from news where id="+n.getId(); ps=con.prepareStatement(sql); a=ps.executeUpdate(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } return a; } /*******查看一个********************************************************************/ public news selectone(news n) { news ne=new news(); try { con=Shujuku.conn(); String sql="select*from news where id=?"; ps=con.prepareStatement(sql); ps.setInt(1, n.getId()); rs=ps.executeQuery(); if(rs.next()){ ne.setId(rs.getInt("id")); ne.setTitle(rs.getString("title")); ne.setContain(rs.getString("contain")); ne.setAutor(rs.getString("autor")); ne.setTypeid(rs.getInt("typeid")); } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } return ne; } /*******修改更新************************************************************************************/ public int update(news n) { int a=0; try { con=Shujuku.conn(); String sql="update news set title=?,contain=?,autor=? where id=?"; ps=con.prepareStatement(sql); ps.setString(1, n.getTitle()); ps.setString(2, n.getContain()); ps.setString(3, n.getAutor()); ps.setInt(4, n.getId()); a=ps.executeUpdate(); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } return a; } }