javaweb商品管理系统实现增删改查代码

以下是一个简单的JavaWeb商品管理系统增删改查的代码示例：

实体类：

public class Goods {
    private int id;
    private String name;
    private String type;
    private double price;
    private int stock;
    //省略getter和setter方法
}

DAO类：

public class GoodsDao {
    private Connection conn = null;
    private PreparedStatement ps = null;
    private ResultSet rs = null;
    
    //添加商品
    public boolean addGoods(Goods goods) {
        boolean flag = false;
        try {
            conn = DBUtil.getConnection();
            String sql = "INSERT INTO goods(name, type, price, stock) VALUES(?, ?, ?, ?)";
            ps = conn.prepareStatement(sql);
            ps.setString(1, goods.getName());
            ps.setString(2, goods.getType());
            ps.setDouble(3, goods.getPrice());
            ps.setInt(4, goods.getStock());
            int count = ps.executeUpdate();
            if(count == 1) {
                flag = true;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.closeAll(conn, ps, rs);
        }
        return flag;
    }
    
    //删除商品
    public boolean deleteGoods(int id) {
        boolean flag = false;
        try {
            conn = DBUtil.getConnection();
            String sql = "DELETE FROM goods WHERE id=?";
            ps = conn.prepareStatement(sql);
            ps.setInt(1, id);
            int count = ps.executeUpdate();
            if(count == 1) {
                flag = true;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.closeAll(conn, ps, rs);
        }
        return flag;
    }
    
    //修改商品
    public boolean updateGoods(Goods goods) {
        boolean flag = false;
        try {
            conn = DBUtil.getConnection();
            String sql = "UPDATE goods SET name=?, type=?, price=?, stock=? WHERE id=?";
            ps = conn.prepareStatement(sql);
            ps.setString(1, goods.getName());
            ps.setString(2, goods.getType());
            ps.setDouble(3, goods.getPrice());
            ps.setInt(4, goods.getStock());
            ps.setInt(5, goods.getId());
            int count = ps.executeUpdate();
            if(count == 1) {
                flag = true;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.closeAll(conn, ps, rs);
        }
        return flag;
    }
    
    //查询商品
    public List<Goods> queryGoods() {
        List<Goods> list = new ArrayList<>();
        try {
            conn = DBUtil.getConnection();
            String sql = "SELECT * FROM goods";
            ps = conn.prepareStatement(sql);
            rs = ps.executeQuery();
            while(rs.next()) {
                Goods goods = new Goods();
                goods.setId(rs.getInt("id"));
                goods.setName(rs.getString("name"));
                goods.setType(rs.getString("type"));
                goods.setPrice(rs.getDouble("price"));
                goods.setStock(rs.getInt("stock"));
                list.add(goods);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.closeAll(conn, ps, rs);
        }
        return list;
    }
}

Servlet类：

public class GoodsServlet extends HttpServlet {
    private GoodsDao dao = new GoodsDao();
    
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        String action = request.getParameter("action");
        if("add".equals(action)) {
            //添加商品
            String name = request.getParameter("name");
            String type = request.getParameter("type");
            double price = Double.parseDouble(request.getParameter("price"));
            int stock = Integer.parseInt(request.getParameter("stock"));
            Goods goods = new Goods();
            goods.setName(name);
            goods.setType(type);
            goods.setPrice(price);
            goods.setStock(stock);
            boolean flag = dao.addGoods(goods);
            if(flag) {
                response.sendRedirect("goods.jsp");
            } else {
                response.getWriter().write("添加失败");
            }
        } else if("delete".equals(action)) {
            //删除商品
            int id = Integer.parseInt(request.getParameter("id"));
            boolean flag = dao.deleteGoods(id);
            if(flag) {
                response.sendRedirect("goods.jsp");
            } else {
                response.getWriter().write("删除失败");
            }
        } else if("update".equals(action)) {
            //修改商品
            int id = Integer.parseInt(request.getParameter("id"));
            String name = request.getParameter("name");
            String type = request.getParameter("type");
            double price = Double.parseDouble(request.getParameter("price"));
            int stock = Integer.parseInt(request.getParameter("stock"));
            Goods goods = new Goods();
            goods.setId(id);
            goods.setName(name);
            goods.setType(type);
            goods.setPrice(price);
            goods.setStock(stock);
            boolean flag = dao.updateGoods(goods);
            if(flag) {
                response.sendRedirect("goods.jsp");
            } else {
                response.getWriter().write("修改失败");
            }
        } else if("query".equals(action)) {
            //查询商品
            List<Goods> list = dao.queryGoods();
            request.setAttribute("list", list);
            request.getRequestDispatcher("goods.jsp").forward(request, response);
        }
    }
    
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }
}

以上代码仅为示例，实际开发中需要根据具体需求进行修改和完善。同时，还需要编写JSP页面来呈现商品信息和与用户交互。