itemdao.java

一个简易的网上书店（jsp+sqlservler+struts）。

package com.webshop.db;
import java.sql.*;
import com.webshop.domain.Item;
import com.webshop.exception.ActionException;

/**
 * @author w
 *
 * To change this generated comment edit the template variable "typecomment":
 * Window>Preferences>Java>Templates.
 * To enable and disable the creation of type comments go to
 * Window>Preferences>Java>Code Generation.
 */
public class ItemDAO {

	Connection con;//数据库连接
	
	String selectItemById="select * from item where itemId=?";
	String selectItemByProductId="select * from item where productId=?";
	
	/**
	 * Constructor for ItemDAO.
	 */
	public ItemDAO() {
		super();
	}
	
	public Item getItemById(String id)
	{
		ProductDAO productDao=new ProductDAO();
		Item item=null;
		try
		{
			con=DatabaseConnection.getConnection();
		}
		catch(Exception e)
		{
			throw new ActionException("不能获得连接，"+e.getMessage());
		}
		try
		{
			PreparedStatement pstmt=con.prepareStatement(selectItemById);
			pstmt.setString(1,id);
			ResultSet rst=pstmt.executeQuery();
          
			if(rst.next())
			{
				item=new Item();
				item.setItemId(rst.getString("itemid"));
				item.setProductId(rst.getString("productid"));
				item.setUnitCost(rst.getFloat("unitcost"));
				item.setListPrice(rst.getFloat("listprice"));
				item.setSupplierId(rst.getInt("supplier"));
				item.setStatus(rst.getString("status"));
				item.setAttr1(rst.getString("attr1"));
				item.setAttr2(rst.getString("attr2"));
				item.setAttr3(rst.getString("attr3"));
				item.setAttr4(rst.getString("attr4"));
				item.setAttr5(rst.getString("attr5"));
				item.setProduct(productDao.getProductById(item.getProductId()));
			}
				con.close();
		}
		catch(SQLException e)
		{
			 throw new ActionException("执行数据库操作发生错误，"+e.getMessage());
		}
		finally
		{
			try
			{
				if(con!=null)
				con.close();
			}
			catch(Exception e2)
			{
			}
		}
		return item;
	}		
	
    /**
     * 根据productid来查找item
     */
    public java.util.Collection getItemByProductId(String productId)
	{
		java.util.Collection items=new java.util.ArrayList();
		
		ProductDAO productDao=new ProductDAO();
		Item item=null;
		try
		{
			con=DatabaseConnection.getConnection();
		}
		catch(Exception e)
		{
			throw new ActionException("不能获得连接，"+e.getMessage());
		}
		try
		{
			PreparedStatement pstmt=con.prepareStatement(selectItemByProductId);
			pstmt.setString(1,productId);
			ResultSet rst=pstmt.executeQuery();
          
			while(rst.next())
			{
				item=new Item();
				item.setItemId(rst.getString("itemid"));
				item.setProductId(rst.getString("productid"));
				item.setUnitCost(rst.getFloat("unitcost"));
				item.setListPrice(rst.getFloat("listprice"));
				item.setSupplierId(rst.getInt("supplier"));
				item.setStatus(rst.getString("status"));
				item.setAttr1(rst.getString("attr1"));
				item.setAttr2(rst.getString("attr2"));
				item.setAttr3(rst.getString("attr3"));
				item.setAttr4(rst.getString("attr4"));
				item.setAttr5(rst.getString("attr5"));
				item.setProduct(productDao.getProductById(item.getProductId()));
				items.add(item);
			}
				con.close();
		}
		catch(SQLException e)
		{
			 throw new ActionException("执行数据库操作发生错误，"+e.getMessage());
		}
		finally
		{
			try
			{
				if(con!=null)
				con.close();
			}
			catch(Exception e2)
			{
			}
		}
		return items;
	}	
}