页面信息的添加和删除操作及作用域

作用域对象

pagaContext ：当前页面作用域

request ： 请求作用域

session ： 当前会话作用域

application ：应用程序

请求转发

作用域对象

pagaContext ： 只能当前页面定义数据，当前页面使用

request ：后端应用程序和页面有请求关系。则数据可以共享

session ：是当前会话有效（同一个人使用同一个浏览器在任何页面都可以数据共享）

application ：是整个服务器有效，所有用户的请求都可以数据共享。

添加

代码操作

Login

package servlet;


import com.bean.q.bean.User;
import dao.UserDao;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;

@WebServlet("/login")
public class Login extends HttpServlet {
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{
        doGet(request,response);
    }
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{
        request.setCharacterEncoding("utf-8");//设置请求的编码格式
        response.setCharacterEncoding("utf-8");//设置响应的编码格式
        response.setContentType("text/html;charset=utf-8");

        String username=request.getParameter("username");
        String password=request.getParameter("password");
    System.out.println(username);
       System.out.println(password);
        UserDao userDao = new UserDao();
        User login = userDao.login(username,password);
        if (login!=null){
            System.out.println("登录成功");
            HttpSession session = request.getSession();
            session.setAttribute("user",login);
           request.getRequestDispatcher("selectAllGoods").forward(request,response);
        }else {
//          request.setAttribute("error_msg","用户名或密码错误,请重新尝试!");
          request.getRequestDispatcher("error.jsp").forward(request,response);
        }
    }
}

package servlet;

import com.bean.q.bean.Goods;
import dao.GoodsDao;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebServlet("/addGoods")
public class AddGoods extends HttpServlet {
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request,response);
    }
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{
        request.setCharacterEncoding("utf-8");//设置请求的编码格式
        response.setCharacterEncoding("utf-8");//设置响应的编码格式

        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("selectAllGoods").forward(request,response);
        }else {
            request.setAttribute("error_msg","添加商品信息失败！");
            request.getRequestDispatcher("error.jsp").forward(request,response);
        }



    }
}

删除

package servlet;

import dao.GoodsDao;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebServlet("/del")
public class DelGoods extends HttpServlet {
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
       int gid = Integer.parseInt(request.getParameter("gid"));

        GoodsDao goodsDao = new GoodsDao();
        int row = goodsDao.deleteById(gid);
        if (row>0){
            request.getRequestDispatcher("selectAllGoods").forward(request,response);
        }else {
            request.setAttribute("error_msg","删除出现了问题");
            request.getRequestDispatcher("error.jsp").forward(request,response);
        }
    }
}