总结一下偶尔项目中用到的mp的高级用法。

valid的判断

数据源优化更新批量操作

spring:
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    druid:
      driver-class-name: com.mysql.cj.jdbc.Driver
      username: admin
      password: admin@110
      url: jdbc:mysql://joolun-mysql:3306/prod_joolun_upms?characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&useSSL=false&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=GMT%2B8&allowMultiQueries=true&allowPublicKeyRetrieval=true&rewriteBatchedStatements=true

最后一个参数rewriteBatchedStatements=true

开启实时日志

# 开启mp的日志（输出到控制台）
mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
    map-underscore-to-camel-case: true
    log-prefix: admin

多表联查

依赖POM

<dependency>    
  <groupId>com.github.yulichang</groupId>    
  <artifactId>mybatis-plus-join-boot-starter</artifactId>    
  <version>1.4.13</version>
</dependency>

创建JOIN MAPPER

public interface FairGroupJoinFairGroupStaffMapper extends MPJBaseMapper<FairGroupStaff> {


}

使用关联查询

@Autowired
private FairGroupJoinFairGroupStaffMapper joinFairGroupStaffMapper;

public R mpJoin(Page page, FairGroupStaff groupStaff) {
    if (!StringUtils.hasLength(groupStaff.getGroupId())) {
        return R.failed("交易团编号不能为空！");
    }
    MPJLambdaWrapper<FairGroupStaff> wrapper = new MPJLambdaWrapper<FairGroupStaff>()
            .select(FairGroupStaff::getId,
                    FairGroupStaff::getIdName,
                    FairGroupStaff::getGroupId,
                    FairGroupStaff::getAccount,
                    FairGroupStaff::getCreateTime,
                    FairGroupStaff::getUpdateTime,
                    FairGroupStaff::getPassword,
                    FairGroupStaff::getPhone,
                    FairGroupStaff::getState,
                    FairGroupStaff::getJob
            ).select(FairGroup::getGroupName)
            .leftJoin(FairGroup.class,
                    FairGroup::getId, FairGroupStaff::getGroupId).orderByDesc(FairGroupStaff::getCreateTime);

    wrapper.eq(FairGroupStaff::getGroupId, groupStaff.getGroupId());
    Page<FairGroupStaffVo> userDTOPage = joinFairGroupStaffMapper.selectJoinPage(page, FairGroupStaffVo.class, wrapper);
    return R.ok(userDTOPage);
}

动态JSON字段

实体类配置

     @TableName(autoResultMap = true)

字段注解

/**
     * 必须开启映射注解
     *
     * @TableName(autoResultMap = true)
     *
     * 选择对应的 JSON 处理器，并确保存在对应的 JSON 解析依赖包
     */
    @TableField(typeHandler = JacksonTypeHandler.class)
    // 或者使用 FastjsonTypeHandler
    // @TableField(typeHandler = FastjsonTypeHandler.class)
    private OtherInfo otherInfo;

例子

添加POM依赖

<dependencies>
  <!-- 其他依赖 -->
  <dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus-boot-starter</artifactId>
    <version>最新版本</version>
  </dependency>
  <dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>最新版本</version>
  </dependency>
</dependencies>

sql准备

CREATE TABLE `product` (
  `id` INT(11) PRIMARY KEY,
  `name` VARCHAR(255),
  `data` JSON
);

实体类

import lombok.Data;

@Data
public class Product {
    private Integer id;
    private String name;
    private JSONObject data; // 使用 JSONObject 来存储 JSON 数据
}

数据插入

INSERT INTO `product` (`id`, `name`, `data`)
VALUES (1, '手机', '{"brand":"Apple","price":799}');

查询操作

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import org.springframework.stereotype.Service;

@Service
public class ProductService {
    private final ProductMapper productMapper;

    public ProductService(ProductMapper productMapper) {
        this.productMapper = productMapper;
    }

    public Product getProductById(Integer id) {
        QueryWrapper<Product> queryWrapper = new QueryWrapper<>();
        queryWrapper.eq("id", id);
        return productMapper.selectOne(queryWrapper);
    }
}

更新操作

import org.springframework.stereotype.Service;

@Service
public class ProductService {
    private final ProductMapper productMapper;

    public ProductService(ProductMapper productMapper) {
        this.productMapper = productMapper;
    }

    public void updateProductPrice(Integer productId, BigDecimal newPrice) {
        Product product = getProductById(productId);
        JSONObject data = product.getData();
        data.put("price", newPrice);
        productMapper.updateById(product);
    }
}

测试类情况

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import java.math.BigDecimal;

@SpringBootTest
public class ProductServiceTest {
    @Autowired
    private ProductService productService;

    @Test
    public void testGetProduct() {
        Integer productId = 1;
        Product product = productService.getProductById(productId);
        System.out.println("查询商品信息结果：");
        System.out.println("Product: " + product);
        System.out.println("价格：" + product.getData().getBigDecimal("price"));

        // 进行更新操作
        BigDecimal newPrice = new BigDecimal(899);
        productService.updateProductPrice(productId, newPrice);

        // 再次查询商品信息
        Product updatedProduct = productService.getProductById(productId);
        System.out.println("\n更新后的商品信息：");
        System.out.println("Product: " + updatedProduct);
        System.out.println("价格：" + updatedProduct.getData().getBigDecimal("price"));
    }
}

其他

以上情况只适用于直接对象,如果需要转换的是List集合,那么目前的MP自带的handler不能满足,需要自定义,需要重写handler

package com.baomidou.mybatisplus.samples.typehandler;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.TypeReference;
import com.baomidou.mybatisplus.extension.handlers.FastjsonTypeHandler;
import com.baomidou.mybatisplus.samples.typehandler.entity.Wallet;

import java.util.List;

/**
 * 自定义复杂类型处理器<br/>
 * 重写 parse 因为顶层父类是无法获取到准确的待转换复杂返回类型数据
 */
public class WalletListTypeFastJsonHandler extends FastjsonTypeHandler {
    public WalletListTypeFastJsonHandler(Class<?> type) {
        super(type);
    }

    @Override
    protected Object parse(String json) {
        return JSON.parseObject(json, new TypeReference<List<Wallet>>() {
        });
    }
}