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				package com.tarena.dao.ipml;								import java.sql.Connection;				import java.sql.ResultSet;				import java.sql.SQLException;				import java.sql.Statement;				import java.util.ArrayList;				import java.util.HashSet;				import java.util.Iterator;				import java.util.List;								import com.tarena.util.*;								import com.tarena.dao.ShoppingCartDao;				import com.tarena.entity.Item;				import com.tarena.entity.Order;				import com.tarena.entity.Product;								public class ShoppingCartImpl implements ShoppingCartDao{										/*					 * 生成帐单,返回帐单号					 * */					public long generateOrder(Order order) {						Connection con=null;						Statement st=null;						ResultSet rs=null;						con=JdbcUtil.getConnection();						try {							st=con.createStatement();							/*							 * 帐单存入数据库,得到帐单号							 * 帐单号在数据表中为主键,设为auto_increment,自动插入记录							 * */													Long orderId=null;							double orderCost=order.getCost();							Long uid=order.getUser().getOid();							String sql="insert into orders(cost,uid) values('"+orderCost+"','"+uid+"')";							st.executeUpdate(sql,Statement.RETURN_GENERATED_KEYS);							/*							 * 设置Statement的executeUpdate方法参数,使其能返回刚才插入数据库							 * 的内容的主键值,即帐单号							 * */							rs=st.getGeneratedKeys();							if(rs.next()){								orderId=rs.getLong(1);							}							/*							 * 将帐单中的条目存入数据库							 * */							List items=order.getItems();							Iterator it=items.iterator();							while(it.hasNext()){								Item item=(Item) it.next();								Integer pid=item.getProduct().getId();								int number=item.getNumber();								double cost=item.getCost();								String sql1="insert into item(pid,number,cost,orderid) values('"+pid+"','"+number+"','"+cost+"','"+orderId+"')";								st.executeUpdate(sql1);							}							return orderId;						} catch (SQLException e) {							e.printStackTrace();						}finally{							JdbcUtil.release(rs, st, con);						}						return 0;					}					/*					 * 列出商品					 * */					public List listProduct() {						List list=new ArrayList();						Connection con=null;						Statement st=null;						ResultSet rs=null;						con=JdbcUtil.getConnection();						String sql="select * from product_bo";						try {							st=con.createStatement();							rs=st.executeQuery(sql);							while(rs.next()){								Product p=new Product();								p.setId(rs.getInt(1));								p.setName(rs.getString(2));								p.setDescription(rs.getString(3));								p.setPrice(rs.getDouble(4));								list.add(p);							}							return list;						} catch (SQLException e) {							e.printStackTrace();							return null;						}finally{							JdbcUtil.release(rs, st, con);						}											/*					 * 根据商品号得到商品					 * */					}					public Product getProduct(int productId) {						Connection con=null;						Statement st=null;						ResultSet rs=null;												con=JdbcUtil.getConnection();						try {							st=con.createStatement();							String sql="select * from product_bo where id="+productId;							rs=st.executeQuery(sql);							Product p=new Product();							if(rs.next()){								p.setId(rs.getInt(1));								p.setName(rs.getString(2));								p.setDescription(rs.getString(3));								p.setPrice(rs.getDouble(4));								return p;							}						} catch (SQLException e) {							e.printStackTrace();							return null;						}finally{							JdbcUtil.release(rs, st, con);						}						return null;					}									}