MybatisPlus集成baomidou-dynamic，多数据源配置使用、MybatisPlus分页分组等操作示例

Mybatisplus特性

无侵入:只做增强，不做改变，引入不会影响现有工程，如丝般光滑，损失小:启动后基本自动注入 CURD，性能基本无损失，直接面向对象操作强大 CRUD 操作：内置通用 Mapper、通用 Service，单表的大部分只能通过少量配置来实现 CRUD 操作，更强大的条件结构，支持满足各种使用需求，支持各种使用需求 Lambda 形式调用：通过 Lambda 表达式，方便编写各种查询条件，无需担心字段错误，支持主键自动生成：支持多达 4 主要策略(唯一的分布式) ID 生成器 - Sequence），可自由配置，完美解决关键问题支持支持完美解决关键问题 ActiveRecord 模式：支持 ActiveRecord 形式调用，实体类只需继承 Model 类可以强大 CRUD 操作支持自定义全局通用操作：支持注入全局通用方法（ Write once, use anywhere ）内置代码生成器：使用代码或 Maven 可以快速生成插件 Mapper 、 Model 、 Service 、 Controller 基于层代码，支持模板引擎，有更多的自定义配置等待您使用内置的分页插件： MyBatis 物理分页，开发者不需要关心具体操作，配置好插件后，写分页等同于普通 List 支持各种数据库的分页插件查询：支持 MySQL、MariaDB、Oracle、DB2、H2、HSQL、SQLite、Postgre、SQLServer 内置性能分析插件等多种数据库：可输出 SQL 句子及其执行时间，建议在开发测试时启用此功能，内置全局拦截插件可以快速找到慢查询：提供全表 delete 、 update 操作智能分析阻断，也可以定制拦截规则，防止误操作

MySQL，Oracle，DB2，H2，HSQL，SQLite，PostgreSQL，SQLServer，Phoenix，Gauss ，ClickHouse，Sybase，OceanBase，Firebird，Cubrid，Goldilocks，csiidb，informix，TDengine，redshift

大梦数据库、虚谷数据库、全国人大金仓数据库、南大通用(华库)数据库、南大通用数据库、神通数据库、汉高数据库、优炫数据库、星瑞格数据库

1、业务需求需要操作多个DB场景。例如，在下订单时，您需要从用户库中查询用户信息，并将订单插入订单库；2、读写分离场景；有两种常见的实现方案：

• AOP + ThreadLocal ，如：Mybatis-plus的多数据源(dynamic-datasource)；
• 语义分析，如：客户端侧：ShardingSphere-Jdbc，服务端侧：ShardingSphere-Proxy，阿里云，腾讯云proxy。

 <dependencies>        <!--springboot依赖于mybatisplus集成Springboot起步-->        <dependency>            <groupId>com.baomidou</groupId>            <artifactId>mybatis-plus-boot-starter</artifactId>             <version>3.4.2</version>        </dependency>        <!--MySQL 驱动依赖-->        <dependency>            <groupId>mysql</groupId>            <artifactId>mysql-connector-java</artifactId>             <version>8.0.27</version>        </dependency>        <!--druid 数据连接池-->        <dependency>            <groupId>com.alibaba</groupId>            <artifactId>druid-spring-boot-starter</artifactId>              <version>1.1.20</version>        </dependency>        <dependency>            <groupId>com.baomidou</groupId>            <artifactId>dynamic-datasource-spring-boot-starter</artifactId>             <version>3.4.1</version>        </dependency>        <dependency>            <groupId>org.postgresql</groupId>            <artifactId>postgresql</artifactId>             <version>42.3.6</version>        </dependency>    </dependencies>

配置文件

mybatis-plus.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImplspring.datasource.dynamic.primary=mysqlspring.datasource.dynamic.strict=falsespring.datasource.dynamic.datasource.mysql.url=jdbc:mysql://192.168.0.111:3306/database?characterEncoding=UTF-8&useUnicode=true&useSSL=false&tinyInt1isBit=false&currentSchema=publicspring.datasource.dynamic.datasource.mysql.username=rootspring.datasource.dynamic.datasource.mysql.password=123456spring.datasource.dynamic.datasource.mysql.driverClassName=com.mysql.cj.jdbc.Driverspring.datasource.dynamic.datasource.mysql.type=com.alibaba.druid.pool.DruidDataSourcespring.datasource.dynamic.datasource.mysql.druid.maxActive=300spring.datasource.dynamic.datasource.mysql.druid.initialSize=20spring.datasource.dynamic.datasource.mysql.druid.maxWait=6000spring.datasource.dynamic.datasource.mysql.druid.minIdle=20spring.datasource.dynamic.datasource.mysql.druid.timeBetweenEvictionRunsMillis=60000spring.datasource.dynamic.datasource.mysql.druid.minEvictableIdleTimeMillis=30000spring.datasource.dynamic.datasource.mysql.druid.validationQuery=select 'x'spring.datasource.dynamic.datasource.mysql.druid.testWhileIdle=truespring.datasource.dynamic.datasource.mysql.druid.testOnBorrow=truespring.datasource.dynamic.datasource.mysql.druid.testOnReturn=falsespring.datasource.dynamic.datasource.postgresql.url= jdbc:postgresql://127.0.0.1:5432/database?characterEncoding=UTF-8&useUnicode=true&useSSL=false&tinyInt1isBit=false&currentSchema=publicspring.datasource.dynamic.datasource.postgresql.username=postgresspring.datasource.dynamic.datasource.postgresql.password=123456spring.datasource.dynamic.datasource.postgresql.driverClassName=org.postgresql.Driverspring.datasource.dynamic.datasource.postgresql.type=com.alibaba.druid.pool.DruidDataSourcespring.datasource.dynamic.datasource.postgresql.druid.maxActive=300spring.datasource.dynamic.datasource.postgresql.druid.initialSize=20spring.datasource.dynamic.datasource.postgresql.druid.maxWait=6000spring.datasource.dynamic.datasource.postgresql.druid.minIdle=20spring.datasource.dynamic.datasource.postgresql.druid.timeBetweenEvictionRunsMillis=60000spring.datasource.dynamic.datasource.postgresql.druid.minEvictableIdleTimeMillis=30000spring.datasource.dynamic.datasource.postgresql.druid.validationQuery=select 'x'spring.datasource.dynamic.datasource.postgresql.druid.testWhileIdle=truespring.datasource.dynamic.datasource.postgresql.druid.testOnBorrow=truespring.datasource.dynamic.datasource.postgresql.druid.testOnReturn=false

配置类

解决分页失效的问题

import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;@Configuration@MapperScan("com.ais.**.mapper.**")public class MybatisPlusConfig {    @Bean    public MybatisPlusInterceptor mybatisPlusInterceptor() {        MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();        interceptor.addInnerInterceptor(new PaginationInnerInterceptor());        return interceptor;    }}

实体类@TableName("tableName")@TableField@TableIdMapper参考代码

import com.UserEntity;import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;import com.baomidou.mybatisplus.core.metadata.IPage;import com.baomidou.mybatisplus.extension.plugins.pagination.Page;import lombok.extern.slf4j.Slf4j;import org.junit.Test;import org.junit.runner.RunWith;import org.springframework.boot.test.context.SpringBootTest;import org.springframework.test.context.junit4.SpringRunner;import javax.annotation.Resource;import java.util.ArrayList;import java.util.List;@Slf4j@RunWith(SpringRunner.class)@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)public class MybatisTest {    @Resource    private UserMapper mapper;    /**     * 分页操作 Mysql  MybatisPlus     */    @Test    public void page() {        IPage page = new Page(2, 2);        IPage iPage = mapper.selectPage(page, null);        System.out.println(iPage.getRecords());    }    /**     * PGSQL SQL分页自定义     */    @Test    public void pagePg() {        IPage page = new Page(1, 1);        IPage iPage = mapper.selectAll(page);        System.out.println(iPage.getRecords());    }    /**     * 分页加排序降序     */    @Test    public void sort() {        IPage page = new Page(1, 10);        QueryWrapper<Entity> queryWrapper = new QueryWrapper<>();        //降序        queryWrapper.orderByDesc("center_Id");        ///升序////        queryWrapper.orderByAsc("center_Id");        IPage iPage = mapper.selectPage(page, queryWrapper);        System.out.println(iPage.getRecords());    }    /**     * 分页加排序降序 lambda 表达式     */    @Test    public void lambdaSort() {        IPage page = new Page(1, 10);        LambdaQueryWrapper<Entity> queryWrapper = new LambdaQueryWrapper<>();        //降序        queryWrapper.orderByDesc(Entity::getCenterId);        ///升序////        queryWrapper.orderByAsc(Entity::getCenterId);        IPage iPage = mapper.selectPage(page, queryWrapper);        System.out.println(iPage.getRecords());    }    /**     * 过滤in条件 lambda 表达式     */    @Test    public void selectIn() {        IPage page = new Page(1, 10);        LambdaQueryWrapper<Entity> queryWrapper = new LambdaQueryWrapper<>();        List<Long> ids = new ArrayList<>();        ids.add(1l);        ids.add(2l);        ids.add(3l);        ids.add(4l);        queryWrapper.in(Entity::getCenterId, ids);//        queryWrapper.notIn(Entity::getCenterId, ids);        IPage iPage = mapper.selectPage(page, queryWrapper);        System.out.println(iPage.getRecords());    }    /**     * 过滤in条件 lambda 表达式     */    @Test    public void selectInSql() {        IPage page = new Page(1, 10);        LambdaQueryWrapper<Entity> queryWrapper = new LambdaQueryWrapper<>();        queryWrapper.inSql(Entity::getCenterId, "select center_Id from center where center_Id>5");//        queryWrapper.notIn(Entity::getCenterId, ids);        IPage iPage = mapper.selectPage(page, queryWrapper);        System.out.println(iPage.getRecords());    }    @Test    public void select() {        IPage page = new Page(1, 10);        LambdaQueryWrapper<Entity> queryWrapper = new LambdaQueryWrapper<>();        IPage iPage = mapper.selectPage(page, queryWrapper);        System.out.println(iPage.getRecords());    }    /**     * max 加分组     */    @Test    public void selectMax() {        IPage page = new Page(1, 10);        QueryWrapper<Entity> queryWrapper = new QueryWrapper<>();        queryWrapper.select("max(center_id) as center_id").groupBy("created_By");        IPage iPage = mapper.selectPage(page, queryWrapper);        System.out.println(iPage.getRecords());    }    /**     * count 加分组     */    @Test    public void selectCount() {        IPage page = new Page(1, 10);        QueryWrapper<Entity> queryWrapper = new QueryWrapper<>();        queryWrapper.select("count(center_id) as count").groupBy("created_By");        mapper.selectPage(page, queryWrapper);    }}