浪漫编码：手把手教你实现校园表白墙功能

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这里写目录标题

表白墙
- 数据准备
- 引入MyBatis和MySQL驱动依赖
- 配置MySQL账号密码
- 编写后端代码
测试代码

表白墙

前面的案例中,我们写了表白墙,但是⼀旦服务器重启,数据仍然会丢失.
要想数据不丢失,需要把数据存储在数据库中.接下来咱们借助MyBatis来实现数据的操作
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数据准备

DROP TABLE IF EXISTS message_info;CREATE TABLE `message_info` (`id` INT ( 11 ) NOT NULL AUTO_INCREMENT,`from` VARCHAR ( 127 ) NOT NULL,`to` VARCHAR ( 127 ) NOT NULL,`message` VARCHAR ( 256 ) NOT NULL,`delete_flag` TINYINT ( 4 ) DEFAULT 0 COMMENT '0-正常, 1-删除',`create_time` DATETIME DEFAULT now(),`update_time` DATETIME DEFAULT now() ON UPDATE now(),PRIMARY KEY ( `id` )
) ENGINE = INNODB DEFAULT CHARSET = utf8mb4;

ONUPDATEnow():当数据发生更新操作时,自动把该列的值设置为now(),
now()可以替换成其他获取时间的标识符,⽐如:CURRENT_TIMESTAMP(),LOCALTIME()等MySQL<5.6.5

只有TIMESTAMP⽀持自动更新
⼀个表只能有⼀列设置自动更新
不允许同时存在两个列,其中⼀列设置了DEFAULTCURRENT_TIMESTAMP,]
TIMESTAMP和DATETIME都⽀持自动更新,且可以有多列

引入MyBatis和MySQL驱动依赖

修改pom文件

<dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter</artifactId><version>3.0.3</version>
</dependency><dependency><groupId>com.mysql</groupId><artifactId>mysql-connector-j</artifactId><scope>runtime</scope>
</dependency>

或者使用插件EditStarters来引入依赖

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配置MySQL账号密码

spring:datasource:url: jdbc:mysql://127.0.0.1:3306/mybatis_test?
characterEncoding=utf8&useSSL=falseusername: rootpassword: rootdriver-class-name: com.mysql.cj.jdbc.Driver
mybatis:configuration: # 配置打印 MyBatis⽇志map-underscore-to-camel-case: true #配置驼峰自动转换

编写后端代码

import lombok.Data;@Data
public class MessageInfo {private Integer id;private String from;private String to;private String message;private Integer deleteFlag;private Date createTime;private Date updateTime;
}

MessageInfoMapper

import com.example.demo.model.MessageInfo;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;
import java.util.List;@Mapper
public interface MessageInfoMapper {@Select("select `id`, `from`, `to`, `message` from message_info where delete_flag=0")List<MessageInfo> queryAll();@Insert("insert into message_info (`from`,`to`, `message`) values(#{from},#{to},#{message})")Integer addMessage(MessageInfo messageInfo);
}

MessageInfoService

import com.example.demo.mapper.MessageInfoMapper;
import com.example.demo.model.MessageInfo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.List;@Service
public class MessageInfoService {@Autowiredprivate MessageInfoMapper messageInfoMapper;public List<MessageInfo> queryAll() {return messageInfoMapper.queryAll();}public Integer addMessage(MessageInfo messageInfo) {return messageInfoMapper.addMessage(messageInfo);}
}

MessageController

import com.example.demo.model.MessageInfo;
import com.example.demo.service.MessageInfoService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.util.StringUtils;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.List;
@RequestMapping("/message")
@RestController
public class MessageController {@Autowiredprivate MessageInfoService messageInfoService;/*** 获取留言列表* @return*/@RequestMapping("/getList")public List<MessageInfo> getList() {return messageInfoService.queryAll();}/*** 发表留言* @param messageInfo* @return*/@RequestMapping("/publish")public boolean publish(MessageInfo messageInfo) {System.out.println(messageInfo);if (StringUtils.hasLength(messageInfo.getFrom())&& StringUtils.hasLength(messageInfo.getTo())&& StringUtils.hasLength(messageInfo.getMessage())) {messageInfoService.addMessage(messageInfo);return true;}return false;}
}