Java（页面的添加和删除）

ゞ浴缸里的玫瑰 2023-10-08 18:27 42阅读 0赞

### 添加的思路 ###

需求:  
从jsp页面添加一条记录到数据库,且显示到界面

分析:  
1.创建jsp页面  
2.创建Servlet>addGoods方法  
1.设置请求编码  
2.获取所有parameter的值  
3. 封装对象  
4.调用addGoods方法  
3.创建Service接口>addGoods方法  
1.调用addGoods(Goods)方法  
4.创建GoodsDao接口>addGoods方法  
1.创建sql语句  
2.获取结果集

#### **代码实现** ####

jsp页面

<%@ page import="java.util.List" %>
    <%@ page import="com.wang.bean.Goods" %>
    <%@ page import="com.wang.bean.User" %><%--
      Created by IntelliJ IDEA.
      User: 小m
      Date: 2023/2/16
      Time: 12:21
      To change this template use File | Settings | File Templates.
    --%>
    <%@ page contentType="text/html;charset=UTF-8" language="java" %>
    
    <%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
    <html>
    <head>
        <title>主页</title>
    </head>
    <body>
           <h2>欢迎来自${user.address}的${user.username}来到主页！</h2>
           <a href="addGoods.jsp"></a>
        <table>
            <tr>
                <th>商品编号</th>
                <th>商品名称</th>
                <th>商品价格</th>
                <th>商品介绍</th>
            </tr>
    
            
           <c:forEach items="${goodsList}" var="goods">
                    <tr>
                        <td>${goods.gid}</td>
                        <td>${goods.gname}</td>
                        <td>${goods.price}</td>
                        <td>${goods.mark}</td>
                        <td>
                            <a href=""></a>
                        </td>
                    </tr>
           </c:forEach>
    
        </table>
    </body>
    </html>

SelectAllGoods

package com.wang.servlet;
    
    import com.wang.bean.Goods;
    import com.wang.dao.GoodsDao;
    
    import javax.servlet.*;
    import javax.servlet.http.*;
    import javax.servlet.annotation.*;
    import java.io.IOException;
    import java.util.List;
    
    @WebServlet("/selectAllGoods")
    public class SelectAllGoods extends HttpServlet {
        @Override
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            System.out.println("SelectAllGoods-doGet...");
            doPost(request,response);
        }
    
        @Override
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            // 1.执行查询业务
            // 2.查询所有商品信息
            GoodsDao goodsDao = new GoodsDao();
            List<Goods> goodsList = goodsDao.selectAllGoods();
            System.out.println(goodsList);
            // 3.把数据传递到前端页面
            // 3.1通过request获取session对象，该对象可以向前端传输数据的容器
            HttpSession session = request.getSession();
            // 4.向session中存入商品信息集合
            session.setAttribute("goodsList",goodsList);
            String id = session.getId();
            System.out.println("sessionID:"+id);
    
            // 4.登录成功,跳转到登录页
            response.sendRedirect("zhuye.jsp");
    
        }
    }

#### **addGoods** ####

public int addgoods(Goods goods) {
            try {
                    con=JDBCUtil.getCon();
                    String sql="insert into t_goods(gname,price,mark) values (?,?,?)";
                    //
                pstm = con.prepareStatement(sql);
                pstm.setObject(1,goods.getGname());
                pstm.setObject(2,goods.getPrice());
                pstm.setObject(3,goods.getMark());
                //
                row=pstm.executeUpdate();
                System.out.println(row);
    
            } catch (Exception e) {
                    e.printStackTrace();
            } finally {
                //释放资源
                JDBCUtil.close(con, pstm);
            }
            return row;
        }

### 删除的思路 ###

思路：

首先利用javaScript获取到复选框中被选中的记录名，将每一个选中的记录名存储到变量中，再传到后台进行批量删除。

<c:forEach items="${goodsList}" var="goods">
                    <tr>
                        <td>${goods.gid}</td>
                        <td>${goods.gname}</td>
                        <td>${goods.price}</td>
                        <td>${goods.mark}</td>
                        <td>
                            <a href="#">修改</a>
                            <a href="del?gid=${goods.gid}">删除</a>
                        </td>
                    </tr>
           </c:forEach>

这里主要是用到jsp中的标签进行显示数据的

然后再看看servlet中的代码

@Override
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            request.setCharacterEncoding("utf-8");
            response.setCharacterEncoding("utf-8");
     
            Goods goods=new Goods();
            goods.setGname(request.getParameter("gname"));
            goods.setPrice(Double.parseDouble(request.getParameter("price")));
            goods.setMark(request.getParameter("mark"));
     
            GoodsDao goodsDao=new GoodsDao();
            int row=goodsDao.add(goods);
     
            if (row>0){
                request.getRequestDispatcher("ServletAllGoods").forward(request,response);
            }else {
                request.setAttribute("error_msg","添加信息失败");
                request.getRequestDispatcher("error_jsp").forward(request,response);
            }
        }
    }

通过Servlet的配置，获取路径将Servlet和tianjia连接起来，便于处理浏览器请求。

public int add(Goods goods) {
            try {
                Class.forName(driver);
                connection = DriverManager.getConnection(url, username, psw);
                String sql = "insert into t_goods(gname,price,mark)values(?,?,?)";
                psmt = connection.prepareStatement(sql);
                psmt.setObject(1, goods.getGname());
                psmt.setObject(2, goods.getPrice());
                psmt.setObject(3, goods.getMark());
                row=psmt.executeUpdate();
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                //8.关闭资源
                try {
     
                    if (psmt != null) {
                        psmt.close();
                    }
                    if (connection != null) {
                        connection.close();
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
            return row;
        }
    }

根据获取到的数据，用字符串分割得到每一个需要删除是名字，最后循环调用删除方法进行删除！