1. 创建一个JSP页面buy.jsp，实现一个查询蛋糕信息的按钮和表格。当用户点击查询蛋糕信息按钮时，通过axios向后端发送一个请求，后端从数据库中查询所有蛋糕信息并将结果返回给前端。前端通过axios接收后端传回的数据，并将数据填充到表格中。 2. 在页面下方添加一个购物车区域，包括一个蛋糕列表和一个购买按钮。当用户复选蛋糕后，将其添加到蛋糕列表中。当用户点击购买按钮时，通过axios向后端发送一个请求，提交所购买的蛋糕信息。后端接收请求后，更新数据库中的剩余蛋糕数量，并将购买的蛋糕信息返回给前端。前端通过axios接收后端传回的数据，并将其填充到购物车列表中。 3. 在后端使用连接池管理数据库连接，并使用JDBC API连接数据库。实现查询所有蛋糕信息、更新蛋糕数量等操作。

好的，下面是一个简单的实现思路和代码示例。 1. 在buy.jsp中添加以下HTML代码： ```html <button onclick="queryCakes()">查询蛋糕信息</button> <table id="cakeTable"> <tr> <th>蛋糕名称</th> <th>蛋糕价格</th> <th>蛋糕数量</th> </tr> </table> <div> <h3>购物车</h3> <table id="cartTable"> <tr> <th>蛋糕名称</th> <th>蛋糕价格</th> <th>蛋糕数量</th> </tr> </table> <button onclick="buyCakes()">购买</button> </div> ``` 2. 在buy.jsp中添加以下JavaScript代码： ```javascript function queryCakes() { axios.get('/cakes').then(response => { const cakes = response.data; const table = document.getElementById('cakeTable'); cakes.forEach(cake => { const row = table.insertRow(); row.insertCell().textContent = cake.name; row.insertCell().textContent = cake.price; row.insertCell().textContent = cake.quantity; }); }); } const cart = []; function addToCart(name, price, quantity) { const item = { name, price, quantity }; cart.push(item); } function buyCakes() { axios.post('/buy', cart).then(response => { const boughtCakes = response.data; const table = document.getElementById('cartTable'); boughtCakes.forEach(cake => { const row = table.insertRow(); row.insertCell().textContent = cake.name; row.insertCell().textContent = cake.price; row.insertCell().textContent = cake.quantity; }); }); } ``` 3. 在后端使用连接池管理数据库连接，并使用JDBC API连接数据库。在Servlet中添加以下代码： ```java 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 javax.naming.Context; import javax.naming.InitialContext; import javax.naming.NamingException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.sql.DataSource; import com.fasterxml.jackson.databind.ObjectMapper; public class CakeServlet extends HttpServlet { private DataSource dataSource; @Override public void init() throws ServletException { try { Context context = new InitialContext(); dataSource = (DataSource) context.lookup("java:comp/env/jdbc/cake"); } catch (NamingException e) { throw new ServletException("Unable to initialize DataSource", e); } } @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { try (Connection connection = dataSource.getConnection()) { PreparedStatement statement = connection.prepareStatement("SELECT * FROM cakes"); ResultSet resultSet = statement.executeQuery(); List<Cake> cakes = new ArrayList<>(); while (resultSet.next()) { Cake cake = new Cake(); cake.setId(resultSet.getInt("id")); cake.setName(resultSet.getString("name")); cake.setPrice(resultSet.getDouble("price")); cake.setQuantity(resultSet.getInt("quantity")); cakes.add(cake); } ObjectMapper mapper = new ObjectMapper(); response.setContentType("application/json"); mapper.writeValue(response.getOutputStream(), cakes); } catch (SQLException e) { throw new ServletException("Unable to query cakes", e); } } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { try (Connection connection = dataSource.getConnection()) { List<Cake> cart = new ObjectMapper().readValue(request.getInputStream(), new TypeReference<List<Cake>>() {}); for (Cake cake : cart) { PreparedStatement statement = connection.prepareStatement( "UPDATE cakes SET quantity = quantity - ? WHERE id = ?"); statement.setInt(1, cake.getQuantity()); statement.setInt(2, cake.getId()); statement.executeUpdate(); } ObjectMapper mapper = new ObjectMapper(); response.setContentType("application/json"); mapper.writeValue(response.getOutputStream(), cart); } catch (SQLException e) { throw new ServletException("Unable to buy cakes", e); } } } ``` 这里假设数据库中有一个名为cakes的表，包含id、name、price和quantity四个字段。在web.xml中配置数据源： ```xml <resource-ref> <description>DB Connection</description> <res-ref-name>jdbc/cake</res-ref-name> <res-type>javax.sql.DataSource</res-type> <res-auth>Container</res-auth> </resource-ref> <resource-env-ref> <description>DB Connection Pool</description> <resource-env-ref-name>jdbc/cake</resource-env-ref-name> <resource-env-ref-type>javax.sql.DataSource</resource-env-ref-type> </resource-env-ref> <resource-env-ref> <description>DB Connection Properties</description> <resource-env-ref-name>jdbc/cake/properties</resource-env-ref-name> <resource-env-ref-type>java.util.Properties</resource-env-ref-type> </resource-env-ref> <resource-ref> <description>DB Connection Pool</description> <res-ref-name>jdbc/cake</res-ref-name> <res-type>javax.sql.DataSource</res-type> <res-auth>Container</res-auth> <mapped-name>java:comp/env/jdbc/cake</mapped-name> <lookup-name>jdbc/cake</lookup-name> </resource-ref> ``` 以上代码示例仅为参考，实际实现中需要根据具体需求进行修改。