javaweb商品管理系统实现增删改查代码

好的，下面是一个简单的JSP/Servlet实现增删改查的代码示例：

首先，我们需要创建一个商品实体类，例如：

public class Product {
    private int id;  // 商品ID
    private String name;  // 商品名称
    private double price;  // 商品价格
    private int stock;  // 商品库存
    
    // getter和setter方法
    // ...
}

接着，我们需要创建一个商品Dao类，实现对商品信息的增删改查操作，例如：

public class ProductDao {
    // 获取数据库连接
    private Connection getConnection() {
        // ...
    }
    
    // 添加商品信息
    public void addProduct(Product product) {
        Connection conn = getConnection();
        PreparedStatement pstmt = null;
        try {
            String sql = "INSERT INTO product(name, price, stock) VALUES (?, ?, ?)";
            pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, product.getName());
            pstmt.setDouble(2, product.getPrice());
            pstmt.setInt(3, product.getStock());
            pstmt.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            // 关闭数据库连接
            // ...
        }
    }
    
    // 查询商品信息
    public List<Product> queryProduct(String keyword) {
        Connection conn = getConnection();
        PreparedStatement pstmt = null;
        ResultSet rs = null;
        List<Product> productList = new ArrayList<>();
        try {
            String sql = "SELECT * FROM product WHERE name LIKE ?";
            pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, "%" + keyword + "%");
            rs = pstmt.executeQuery();
            while (rs.next()) {
                Product product = new Product();
                product.setId(rs.getInt("id"));
                product.setName(rs.getString("name"));
                product.setPrice(rs.getDouble("price"));
                product.setStock(rs.getInt("stock"));
                productList.add(product);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            // 关闭数据库连接
            // ...
        }
        return productList;
    }
    
    // 修改商品信息
    public void updateProduct(Product product) {
        Connection conn = getConnection();
        PreparedStatement pstmt = null;
        try {
            String sql = "UPDATE product SET name=?, price=?, stock=? WHERE id=?";
            pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, product.getName());
            pstmt.setDouble(2, product.getPrice());
            pstmt.setInt(3, product.getStock());
            pstmt.setInt(4, product.getId());
            pstmt.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            // 关闭数据库连接
            // ...
        }
    }
    
    // 删除商品信息
    public void deleteProduct(int id) {
        Connection conn = getConnection();
        PreparedStatement pstmt = null;
        try {
            String sql = "DELETE FROM product WHERE id=?";
            pstmt = conn.prepareStatement(sql);
            pstmt.setInt(1, id);
            pstmt.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            // 关闭数据库连接
            // ...
        }
    }
}

最后，我们需要创建一个Servlet，实现对商品信息的请求处理，例如：

public class ProductServlet extends HttpServlet {
    private ProductDao productDao = new ProductDao();
    
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String action = request.getParameter("action");
        if ("add".equals(action)) {
            // 添加商品信息
            String name = request.getParameter("name");
            double price = Double.parseDouble(request.getParameter("price"));
            int stock = Integer.parseInt(request.getParameter("stock"));
            Product product = new Product();
            product.setName(name);
            product.setPrice(price);
            product.setStock(stock);
            productDao.addProduct(product);
            response.sendRedirect(request.getContextPath() + "/product.jsp");
        } else if ("query".equals(action)) {
            // 查询商品信息
            String keyword = request.getParameter("keyword");
            List<Product> productList = productDao.queryProduct(keyword);
            request.setAttribute("productList", productList);
            request.getRequestDispatcher("/product.jsp").forward(request, response);
        } else if ("update".equals(action)) {
            // 修改商品信息
            int id = Integer.parseInt(request.getParameter("id"));
            String name = request.getParameter("name");
            double price = Double.parseDouble(request.getParameter("price"));
            int stock = Integer.parseInt(request.getParameter("stock"));
            Product product = new Product();
            product.setId(id);
            product.setName(name);
            product.setPrice(price);
            product.setStock(stock);
            productDao.updateProduct(product);
            response.sendRedirect(request.getContextPath() + "/product.jsp");
        } else if ("delete".equals(action)) {
            // 删除商品信息
            int id = Integer.parseInt(request.getParameter("id"));
            productDao.deleteProduct(id);
            response.sendRedirect(request.getContextPath() + "/product.jsp");
        }
    }
}

以上是一个简单的增删改查代码示例，具体实现还需要根据您的需求进行调整。希望可以帮到您。