web尝试---信箱

标签：web note java String id --- import 信箱 public

功能

写信（增加）+读信（显示所有信件）

目录结构

数据库设计

刚开始设计了主键为id，但是后来不想用id这个属性了，但是代码写完了很麻烦不想改了。

感觉我这个id属性设置的简直多余！！！！

id重复了没法添加，但是用户怎么知道写的id是否重复呢，他也不应该看数据库挑一个没用过的id啊。

后端代码

dao层

里面有两个方法：增加+查询所有

package com.xx.note.dao;import com.xx.note.pojo.Note;
import com.xx.note.utils.JdbcBase;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

public class NoteDao {
    public void addNote(Note note) {
        try {
            Connection c = JdbcBase.getConnection();
            String sql = "INSERT INTO note (id, name, content, date) VALUES (?, ?, ?, ?)";
            PreparedStatement ps = c.prepareStatement(sql);
            ps.setInt(1, note.getId());
            ps.setString(2, note.getName());
            ps.setString(3, note.getContent());
            ps.setDate(4, note.getDate());

            ps.executeUpdate();

            ps.close();
            c.close();
        } catch (SQLException e) {
            e.printStackTrace();
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    public List<Note> getAllNotes() {
        List<Note> noteList = new ArrayList<>();
        try {
            Connection c = JdbcBase.getConnection();
            String sql = "SELECT * FROM note";
            PreparedStatement ps = c.prepareStatement(sql);
            ResultSet rs = ps.executeQuery();

            while (rs.next()) {
                Note note = new Note();
                note.setId(rs.getInt("id"));
                note.setName(rs.getString("name"));
                note.setContent(rs.getString("content"));
                note.setDate(rs.getDate("date"));

                noteList.add(note);
            }

            rs.close();
            ps.close();
            c.close();
        } catch (SQLException e) {
            e.printStackTrace();
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
        return noteList;
    }
}

pojo实体

4个属性，对应get，set等等方法，全参构造，空参构造...

package com.xx.note.pojo;

import java.sql.Date;

public class Note {
    private int id;
    private String name;
    private String content;
    private Date date;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    public Date getDate() {
        return date;
    }

    public void setDate(Date date) {
        this.date = date;
    }

    public Note(int id, String name, String content, Date date) {
        this.id = id;
        this.name = name;
        this.content = content;
        this.date = date;
    }

    public Note() {
    }

    @Override
    public String toString() {
        return "Note{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", content='" + content + '\'' +
                ", date=" + date +
                '}';
    }
}

service层

调用dao层的方法

package com.xx.note.service;

import com.xx.note.dao.NoteDao;
import com.xx.note.pojo.Note;

import java.util.List;

public class NoteService {
    private NoteDao noteDao = new NoteDao();

    public void addNote(Note note) {
        noteDao.addNote(note);
    }

    public List<Note> getAllNotes() {
        return noteDao.getAllNotes();
    }
}

servlet

有读信和写信两个功能，写了两个servlet。

NoteReadServlet

package com.xx.note.servlet;
import com.alibaba.fastjson.JSON;
import com.xx.note.pojo.Note;
import com.xx.note.service.NoteService;

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.util.List;

@WebServlet("/read")

public class NoteReadServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 获取笔记列表
        List<Note> notes = new NoteService().getAllNotes(); // 获取笔记的逻辑

        request.setAttribute("notes",notes);
        request.getRequestDispatcher("/read.jsp").forward(request,response);

        //json好使嘿嘿嘿
//        //将对象转换为json字符串
//        String json = JSON.toJSONString(notes);
//        //设置编码格式
//        response.setCharacterEncoding("utf-8");
//        response.getWriter().print(json);
    }
}

NoteWriteServlet

提交后，提示成功，以html格式打印到网页

package com.xx.note.servlet;
import com.xx.note.pojo.Note;
import com.xx.note.service.NoteService;

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;
import java.text.SimpleDateFormat;
import java.util.Date;

@WebServlet("/write")
public class NoteWriteServlet extends HttpServlet {

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        // 获取表单数据
        int id = Integer.parseInt(request.getParameter("id"));
        String name = request.getParameter("name");
        String content = request.getParameter("content");
        String dateStr = request.getParameter("date");

        System.out.println("测试一下嘿嘿嘿");

        // 将字符串日期转换为 Date 对象
        Date date = null;
        try {
            date = new SimpleDateFormat("yyyy-MM-dd").parse(dateStr);
        } catch (Exception e) {
            e.printStackTrace();
        }

        // 这里可以将 Note 对象存入数据库或进行其他处理
        Note note = new Note();
        note.setId(id);
        note.setName(name);
        note.setContent(content);
//        note.setDate((java.sql.Date) date);
        note.setDate(new java.sql.Date(date.getTime()));

        NoteService noteService = new NoteService();
        //调用Service层增加方法（add），增加记录
        noteService.addNote(note);

        // 响应提交结果
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        out.println("<html><body>");
        out.println("<h1>提交成功啦!!!</h1>");
        out.println("<p>ID: " + note.getId() + "</p>");
        out.println("<p>Name: " + note.getName() + "</p>");
        out.println("<p>Content: " + note.getContent() + "</p>");
        out.println("<p>Date: " + new SimpleDateFormat("yyyy-MM-dd").format(note.getDate()) + "</p>");
        out.println("</body></html>");
    }
    @Override
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);//Get请求和Post请求的处理是一样的，所以把request、response转交给Post方法就好
    }
}

utils工具类

放数据库驱动的几行代码

package com.xx.note.utils;

import com.xx.note.pojo.Note;
import com.xx.note.service.NoteService;

import java.sql.Connection;
import java.sql.DriverManager;
import java.util.List;

public class JdbcBase {
    public static String DBDRIVER = "com.mysql.jdbc.Driver";
    public static String DBURL = "jdbc:mysql://localhost:3306/note?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=Asia/Shanghai&autoReconnect=true&failOverReadOnly=false&allowPublicKeyRetrieval=true";
    public static String DBUSER = "root";
    public static String PASSWORD = "123456";
    public static Connection getConnection() throws Exception {
        Class.forName(DBDRIVER);
        return DriverManager.getConnection(DBURL, DBUSER, PASSWORD);
    }
    public static void main(String[] args) {
        try {
            Connection conn = JdbcBase.getConnection();
            System.out.println("数据库连接成功！！！");
            conn.close();
        } catch (Exception e) {
            e.printStackTrace();
            System.out.println("数据库连接失败！！！");
        }
//        测试方法1好用
//        System.out.println(new NoteService().getAllNotes());
//        测试方法2是否好用
//        new NoteService().addNote(new Note());

    }
}

前端代码

用的jsp

index.jsp

<%--
  Created by IntelliJ IDEA.
  User: 86158
  Date: 2024/7/10
  Time: 10:09
  To change this template use File | Settings | File Templates.
--%>
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %>
<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8"/>
    <title>来自星星的信箱
标签：web,note,java,String,id,---,import,信箱,public	

From： https://blog.csdn.net/yesyesyes_yes/article/details/141678235

功能