表白墙项目（JAVA实现）

1、在html里

class使用.

id使用#

2、记得引入响应依赖（举例lombok）

3、messageController

package com.example.demo.demos.web;
import org.springframework.util.StringUtils;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.ArrayList;
import java.util.List;
@RequestMapping("/message")
@RestController
public class massageController {
    //学过数据库的可以将这里改为数据库操作
    public List<MessageInfo> messageInfos=new ArrayList<>();
    //提交留言
    @RequestMapping("/publish")
    public boolean publishMessage(MessageInfo messageInfo){
        if(!StringUtils.hasLength(messageInfo.getMessage())
                ||!StringUtils.hasLength(messageInfo.getTo())
                ||!StringUtils.hasLength(messageInfo.getFrom())
        ){
            return false;
        }
        //暂时存放在内存中
        messageInfos.add(messageInfo);
        return true;
    }
    @RequestMapping("/getlist")
    public List<MessageInfo> getlist(){
        return messageInfos;
    }
}

4、MessageInfo

package com.example.demo.demos.web;

import lombok.Data;
import lombok.Getter;

//可以省去我们的get和set方法，其他类可以直接调用
@Data
public class MessageInfo {
    private String from;
    private String to;
    private  String message;
}

5、messagewall前端代码

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>留言板</title>
    <style>
        .container {
            width: 350px;
            height: 300px;
            margin: 0 auto;
            /* border: 1px black solid; */
            text-align: center;
        }

        .grey {
            color: grey;
        }

        .container .row {
            width: 350px;
            height: 40px;

            display: flex;
            justify-content: space-between;
            align-items: center;
        }

        .container .row input {
            width: 260px;
            height: 30px;
        }

        #submit {
            width: 350px;
            height: 40px;
            background-color: orange;
            color: white;
            border: none;
            margin: 10px;
            border-radius: 5px;
            font-size: 20px;
        }
    </style>
</head>

<body>
<div class="container">
    <h1>留言板</h1>
    <p class="grey">输入后点击提交, 会将信息显示下方空白处</p>
    <div class="row">
        <span>谁:</span> <input type="text" name="" id="from">
    </div>
    <div class="row">
        <span>对谁:</span> <input type="text" name="" id="to">
    </div>
    <div class="row">
        <span>说什么:</span> <input type="text" name="" id="say">
    </div>
    <input type="button" value="提交" id="submit" onclick="submit()">
    <!-- <div>A 对 B 说: hello</div> -->
</div>

<script src="https://cdn.bootcdn.net/ajax/libs/jquery/3.6.4/jquery.min.js"></script>
<script>
          //页面加载后信息留在页面上
          $.ajax({
             type:"get",
             url:"/message/getlist",
             success:function(messages){
                for(var message of messages){
                var html="<div>"+message.from+"对 "+message.to+" 说: "+message.message+"</div> "
                $(".container").append(html);
            }
             }
          });
        function submit(){
            //1. 获取留言的内容
            var from = $('#from').val();
            var to = $('#to').val();
            var say = $('#say').val();
            if (from== '' || to == '' || say == '') {
                return;
            }
            $.ajax({
                type:"post",
                url:"/message/publish",
                data:{
                    from:from,
                    to:to,
                    message:say
                },
                success:function(result){
                    if(result==true){
                        //添加成功
                         //2. 构造节点
                        var divE = "<div>"+from +"对" + to + "说:" + say+"</div>";
                        //3. 把节点添加到页面上
                         $(".container").append(divE);
                         //4. 清空输入框的值
                        $('#from').val("");
                        $('#to').val("");
                        $('#say').val("");
                    }else{
                        //弹一个框
                        alert("发表失败")
                    }
                }
            });
        }

    </script>
</body>

</html>

6、前端代码中涉及到的后端代码部分说明

（1）前端获取留言内容部分