使用jsp和servlet实现网上书城（简易版）

package com.dao; import com.bean.Book; import org.apache.commons.dbutils.QueryRunner; import org.apache.commons.dbutils.handlers.BeanListHandler; import org.apache.commons.dbutils.handlers.ScalarHandler; import com.utils.DBCP; import java.util.ArrayList; import java.util.List; public class BooksUtilsDao { public static QueryRunner runner = new QueryRunner(DBCP.getDataSource()); //查询书表 @SuppressWarnings({ "unchecked", "rawtypes" }) public List<Book> findAll() throws Exception{ ArrayList<Book> list = new ArrayList<Book>(); String sql = "select * from books"; list = (ArrayList<Book>) runner.query(sql, new BeanListHandler(Book.class)); return list; } //根据id查询书的信息 @SuppressWarnings({ "unchecked", "rawtypes" }) public List<Book> findId(String id) throws Exception{ ArrayList<Book> list = new ArrayList<Book>(); String sql = "select * from books where id = ?"; list = (ArrayList<Book>) runner.query(sql, new BeanListHandler(Book.class), id); return list; } //根据id增加书的数量 public void add(String id) throws Exception{ String sql = "update books set number = number+'1' where id = ?"; runner.update(sql, new Object[]{id}); } //根据id减少书的数量 public void reduce(String id) throws Exception{ String sql = "update books set number = number-'1' where id = ?"; runner.update(sql, new Object[]{id}); } //清空购物车 public void remove(String id) throws Exception{ String sql = "update books set number = 0, totalprice = 0 where id = ?"; runner.update(sql, new Object[]{id}); } //计算购物车单本图书的总价格（小计） public void totalprice(String id) throws Exception{ String sql = "update books set totalprice = price*number where id = ?"; runner.update(sql, new Object[]{id}); } //计算购物车总价格 public double sumprice() throws Exception{ String sql = "select sum(totalprice) from books "; @SuppressWarnings({ "unchecked", "rawtypes" }) double sumprice = (double) runner.query(sql, new ScalarHandler()); return sumprice; } //计算购物车总数量 public double sumnumber() throws Exception{ String sql = "select sum(number) from books "; @SuppressWarnings({ "unchecked", "rawtypes" }) double sumnumber = (double) runner.query(sql, new ScalarHandler()); return sumnumber; } //将数据库购物车信息删除 public void deletecart() throws Exception{ String sql = "update books set number = 0, totalprice = 0"; runner.update(sql); } }