JDBC实践-编辑功能的实现

2017-12-06 22:12:08

1. 建立EditUserServlet文件,文件内容如下

package com.ungly.servlet;

import com.ungly.bean.User;
import com.ungly.service.ListService;

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;
import java.io.PrintWriter;

@WebServlet(name = "EditUserServlet",urlPatterns = "/editUser")
public class EditUserServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        request.setCharacterEncoding("UTF-8"); //设置编码
        String id = request.getParameter("id");
        String username = request.getParameter("username");
        ListService listService = new ListService();
        boolean status = listService.editUser(id, username);
        if(status)
        {
            response.sendRedirect("/List");

        }else{
            response.setContentType("text/html;charset=utf-8;");
            PrintWriter writer = response.getWriter();
            writer.write("编辑失败");
        }

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        request.setCharacterEncoding("UTF-8"); //设置编码
        String id = request.getParameter("id"); //接收id参数
        ListService listService = new ListService();
        User user = listService.showUser(id);
        if(user != null)
        {
            request.setAttribute("user",user);
            request.getRequestDispatcher("/WEB-INF/jsp/front/editUser.jsp").forward(request,response);

        }else{

        }
    }
}

2. 在UserDao.java文件中,添加showUser和editUser方法,内容如下

public User showUser(Integer id)
    {
        User user = new User();
        String sql = "SELECT id,username FROM user where id =?";
        try {
            this.preparedStatement = this.conn.prepareStatement(sql);
            this.preparedStatement.setInt(1,id);
            ResultSet resultSet = this.preparedStatement.executeQuery();
            while (resultSet.next())
            {

                user.setId(resultSet.getString("id"));
                user.setUsername(resultSet.getString("username"));
            }



        } catch (SQLException e) {
            e.printStackTrace();
        }

        return user;
    }

    public boolean editUser(Integer id,String username)
    {
        if(id>0)
        {
            try {
                String sql = "UPDATE user SET username=? WHERE id =?";
                this.preparedStatement = this.conn.prepareStatement(sql);
                this.preparedStatement.setString(1,username);
                this.preparedStatement.setInt(2,id);
                int i = this.preparedStatement.executeUpdate();
                if(i>0)
                {
                    this.status = true;
                }else{
                    this.status = false;
                }


            }catch (SQLException e) {
                e.printStackTrace();
            }finally {
                try {
                    this.conn.close();
                    this.preparedStatement.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
            }
        }else{

            this.status = false;
        }

        return this.status;


    }

3. 在LisetService文件中添加showUser和editUser方法,内容如下

public User showUser(String id)
    {

        return this.userDao.showUser(Integer.valueOf(id));

    }

    public boolean editUser(String id,String username)
    {
        return this.userDao.editUser(Integer.valueOf(id),username);
    }

4. 添加editUser.jsp文件,内容如下

<%--
  Created by IntelliJ IDEA.
  User: nosay
  Date: 17-12-5
  Time: 下午3:31
  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>Title</title>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <link href="https://cdn.bootcss.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet">
</head>
<body>

<div class="container">
    <div class="row clearfix">
        <div class="col-md-12 column">
            <form role="form" method="post" action="/editUser">
                <div class="form-group">
                    <label for="username">用户名</label><input class="form-control" name="username" value="${requestScope.user.username}" id="username" type="username" />
                    <input type="hidden" name="id" value="${requestScope.user.id}" />
                </div>
                <button type="submit" class="btn btn-default">Submit</button>
            </form>
        </div>
    </div>
</div>

</body>
</html>

这样实现了所有CURD功能,很简单,算是一个入门的项目吧.

相应的练习项目地址:
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