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
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
配置MySQL账号密码
spring: datasource: url: jdbc:mysql://127.0.0.1:3306/mybatis_test? characterEncoding=utf8&useSSL=false username: root password: root driver-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 { @Autowired private 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 { @Autowired private 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; } }
测试代码
部署程序,验证服务器是否能正确响应:http://127.0.0.1:8080/messagewall.html
输入留言信息,点击提交,发现页面列表显示新的数据,并且数据库中也添加了⼀条记录.
重启服务,页面显示不变.
