mybatis-plus

可以省略很多基本的增删改查
先导包

<dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.3.1.tmp</version>
        </dependency>
        <!--mysql驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
            <version>8.0.13</version>
        </dependency>

spring.datasource.username=root
spring.datasource.password=root
spring.datasource.url=jdbc:mysql://127.0.0.1:3307/siterec_datacenter?useUnicode=true&useSSL=false&characterEncoding=utf8&serverTimezone=Asia/Shanghai
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
# 配置日志
mybatis-plus.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl

然后写一个mapper

package com.dx.dx_iteminfo.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.dx.dx_iteminfo.entity.Student;
import org.springframework.stereotype.Repository;

@Repository
public interface StuMapper extends BaseMapper<Student> {
}

自然要有student实体类

package com.dx.dx_iteminfo.entity;

import com.baomidou.mybatisplus.annotation.*;
import lombok.*;
import lombok.experimental.Accessors;

import java.io.Serializable;
import java.util.Date;

@Data
@EqualsAndHashCode(callSuper = false)
@Accessors(chain = true)
@ToString
@AllArgsConstructor
@NoArgsConstructor
@TableName(value = "student")//指定表名默认和类名一致，可以自动配置
public class Student implements Serializable {
//    @TableId(type = IdType.AUTO)
    private Long id;
    private String name;
    private Integer age;
    private String email;
    @TableField(fill = FieldFill.INSERT)
    private Date createTime;
    @TableField(fill = FieldFill.INSERT_UPDATE)
    private Date updateTime;
    @Version // 乐观锁version注解
    private Integer version;
    private String extra;
// @TableField里面可以指定对应表中的字段，
//默认会将驼峰转成下划线，还有其他属性可以设置，比如该字段不希望存入表中，
//可以@TableField(exist = false)

}

启动类里面需要扫描一下

package com.dx.dx_iteminfo;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@MapperScan("com.dx.dx_iteminfo.mapper")
@SpringBootApplication
public class DxIteminfoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DxIteminfoApplication.class, args);
    }

}

自动生成创建修改时间需要设置一个拦截

package com.dx.dx_iteminfo.handler;

import com.baomidou.mybatisplus.core.handlers.MetaObjectHandler;
import lombok.extern.slf4j.Slf4j;
import org.apache.ibatis.reflection.MetaObject;
import org.springframework.stereotype.Component;
import sun.misc.Contended;

import java.util.Date;

@Slf4j
@Component
public class MyMetaObjectHandler implements MetaObjectHandler {

    // 插入时的填充策略
    @Override
    public void insertFill(MetaObject metaObject) {
        log.info("start insert fill");
        this.setFieldValByName("createTime", new Date(), metaObject);
        this.setFieldValByName("lastUpdateTime", new Date(), metaObject);
    }

    // 更新时的填充策略
    @Override
    public void updateFill(MetaObject metaObject) {
        log.info("start update fill.....");
        this.setFieldValByName("lastUpdateTime", new Date(), metaObject);

    }
}

还有一个乐观锁的

package com.dx.dx_iteminfo.config;

import com.baomidou.mybatisplus.core.parser.ISqlParser;
import com.baomidou.mybatisplus.extension.parsers.DynamicTableNameParser;
import com.baomidou.mybatisplus.extension.parsers.ITableNameHandler;
import com.baomidou.mybatisplus.extension.plugins.OptimisticLockerInterceptor;
import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;
import org.apache.ibatis.reflection.MetaObject;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.transaction.annotation.EnableTransactionManagement;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

@MapperScan("com.dx.dx_iteminfo.mapper")
@EnableTransactionManagement
@Configuration // 配置类
public class MyBatisPlusConfig {

    // 注册乐观锁插件
    @Bean
    public OptimisticLockerInterceptor optimisticLockerInterceptor(){
        return new OptimisticLockerInterceptor();
    }
}