categorybean.java

简易商品管理系统代码

package jdbcbook.ch08;
import java.sql.*;
import java.util.Collection;
import java.util.Vector;

import jdbcbook.pub.util.*;
/*
 * 商品分类处理Bean
 */
public class CategoryBean
{
	//增加商品分类信息
	public boolean addCategory(Category category)
	{
		if(category==null||StringUtil.isEmptyString(category.getName()))
			return false;
		Connection conn=null;
		Statement st=null;
		try
		{
			conn=DatabaseBean.getConnection();
			st=conn.createStatement();
			//判断商品分类名称是否重复
			boolean exists=false;
			String sql="select ID from category where name='"+category.getName()+"'";
			ResultSet rs=st.executeQuery(sql);
			while(rs.next())
			{
				exists=true;
			}
			rs.close();
			if(exists)
				return false;
			//增加商品分类信息到数据库
			sql="insert into category(categoryid,name) values('"+DatabaseBean.getMaxID("category")+"','"+category.getName()+"')";
			int nResult=st.executeUpdate(sql);
			return nResult==1;
		}
		catch(SQLException e)
		{
			e.printStackTrace(System.err);
			return false;
		}
		finally
		{
			DatabaseBean.close(null,st,conn);
		}
	}
	//查询商品分类信息
	public Collection queryCategory(Category category)
	{
		Vector vt=new Vector();
		Connection conn=null;
		Statement st=null;
		ResultSet rs=null;
		try
		{
			conn=DatabaseBean.getConnection();
			st=conn.createStatement();
			String sql="select category,name from category";
			//如果输入了分类名称,就使用模糊匹配,否则查询所有
			if(category!=null&&!StringUtil.isEmptyString(category.getName()))
				sql=sql+" where name like '%"+category.getName()+"%'";
			//增加排序规则
			sql=sql+" order by name asc";
			//执行sql语句
			rs=st.executeQuery(sql);
			while(rs.next())
			{
				//得到查询结果
				Category c=new Category();
				c.setCategoryID(rs.getInt(1));
				c.setName(rs.getString(2));
				vt.add(c);
			}
		}
		catch(Exception e)
		{
			e.printStackTrace(System.err);
		}
		finally
		{
			//释放资源并关闭数据库
			DatabaseBean.close(rs,st,conn);
		}
		return vt;
	}
	//修改商品分类信息
	public boolean updateCategory(Category category)
	{
		if(category==null||category.getCategoryID()<=0)
			return false;
		Connection conn=null;
		Statement st=null;
		try
		{
			//得到数据库连接
			conn=DatabaseBean.getConnection();
			st=conn.createStatement();
			//判断分类修改后是否与其他记录重复
			boolean exists=false;
			String sql="select categoryid from category where name='"+category.getName()+"'";
			//执行查询语句
			ResultSet rs=st.executeQuery(sql);
			while(rs.next())
			{
				//判断是否重复
				exists=(category.getCategoryID()!=rs.getInt(1));
			}
			rs.close();
			if(exists)
				return false;
			//修改商品分类信息到数据库
			sql="update category set name='"+category.getName()+"' where categoryid='"+category.getCategoryID()+"'";
			int nResult=st.executeUpdate(sql);
			return nResult==1;
		}
		catch(SQLException e)
		{
			e.printStackTrace(System.err);
			return false;
		}
		finally
		{
			//关闭数据库的链接
			DatabaseBean.close(null, st, conn);
		}
	}
	//删除商品分类信息
	public boolean delCategory(Category category)
	{
		if(category.getCategoryID()<=0)
			return false;
		Connection conn=null;
		Statement st=null;
		try
		{
			//得到数据库连接
			conn=DatabaseBean.getConnection();
			st=conn.createStatement();
			//删除商品分类信息sql语句
			String sql="delete from category where categoryid='"+category.getCategoryID()+"'";
			//执行更新语句
			int nResult=st.executeUpdate(sql);
			return nResult==1;
		}
		catch(SQLException e)
		{
			e.printStackTrace(System.err);
			return false;
		}
		finally
		{
			//关闭数据库连接
			DatabaseBean.close(null, st, conn);
		}
	}
	
}