mybatis-plus 简单使用

依赖

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.6.10</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.angen</groupId>
    <artifactId>mp_test</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>mp_test</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <!--mabatis-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.2.0</version>
        </dependency>
        <!--mysql-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <!--mp-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.3</version>
        </dependency>
        <!--引入druid数据源-->
        <!-- https://mvnrepository.com/artifact/com.alibaba/druid -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.2.6</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

配置

server:
  port: 8081
  #解决乱码
  http:
    encoding:
      charset: UTF-8
      force: true
      enabled: true
    messages:
      encoding: UTF-8
    banner:
      charset: UTF-8
spring:
  datasource:
    username: root
    password: root
    url: jdbc:mysql://localhost:3306/test_mybatis?useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai
    # 8以上的驱动url 需要加上时区serverTimezone=Asia/Shanghai
    driver-class-name: com.mysql.cj.jdbc.Driver
    type: com.alibaba.druid.pool.DruidDataSource
    #自动往数据库建表
    #    schema:
    #      - classpath:department.sql
    initialSize: 5
    minIdle: 5
    maxActive: 20
    maxWait: 60000
    timeBetweenEvictionRunsMillis: 60000
    minEvictableIdleTimeMillis: 300000
    validationQuery: SELECT 1 FROM DUAL
    testWhileIdle: true
    testOnBorrow: false
    testOnReturn: false
    poolPreparedStatements: true
    #   配置监控统计拦截的filters，去掉后监控界面sql无法统计，'wall'用于防火墙
    filters: stat,wall,log4j
    maxPoolPreparedStatementPerConnectionSize: 20
    useGlobalDataSourceStat: true
    connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=500
  mvc:
    pathmatch:
      matching-strategy: ant_path_matcher
#mybatis配置
#mapper-locations: classpath:mapper/UserMapper.xml指定加载这个文件
mybatis:
  mapper-locations: classpath:mapper/*Mapper.xml
  type-aliases-package: com.angen.entity
#mybatis-plus
mybatis-plus:
  configuration:
    #关闭实体类成员属性必须用驼峰命名
    map-underscore-to-camel-case: false
    #开启输出sql语句
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
  #设置mybatis_plus的全局配置
  global-config:
    db-config:
      #设置表前缀
      table-prefix: t_
      #配置统一主键生成策略 auto自动递增
      id-type: auto

扫描mapper接口

@SpringBootApplication
@MapperScan("com.angen.mapper")
public class MpTestApplication {

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

}

实体类上加上

@TableName("表名")

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在mapper层使用mybatis-plus

package com.angen.mapper;

import com.angen.entity.GameBigcate;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import org.springframework.stereotype.Repository;

/**
 * 继承BaseMapper<T>
 *     泛型是我们的实体类
 * */
@Repository
public interface CateMapper extends BaseMapper<GameBigcate> {
}

service层使用我们的mybatis-plus

package com.angen.service;

import com.angen.entity.GameBigcate;
import com.baomidou.mybatisplus.extension.service.IService;


/**
 * 继承IService
 *      泛型就是对应的实体类
 */
public interface CateService extends IService<GameBigcate> {
}

然后我们要创建对应的实现类

package com.angen.service.impl;

import com.angen.entity.GameBigcate;
import com.angen.mapper.CateMapper;
import com.angen.service.CateService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import org.springframework.stereotype.Service;


/**
 * 首先实现自己的CateService接口
 * 然后由于CateService接口继承了IService<GameBigcate>
 *     所以我们需要重写IService里面的一些方法
 *     但是mybatis-plus给我们提供了ServiceImpl<CateMapper, GameBigcate>
 *         泛型第一个参数是对应的mapper,第二个参数是实体类
 */
@Service
public class CateServiceImpl extends ServiceImpl<CateMapper, GameBigcate> implements CateService {
}

这样我们可以使用通用的mybatis-plus里面的功能，又可以在service实现类中自定义我们自己的功能。

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条件构造器

mybatis-plus中wrapper的用法（详细）_乞力马扎罗の黎明的博客-CSDN博客_wrapper.apply