Mybatisplus详解如何注入自定义的SQL【mysql优化】

目录

• SQL 注入器
• 第一步重写getMethodList
• 第二步定义自己的SQL方法类
• 第三步定义添加了自定义方法的Mapper类
• 测试调用
• 遗留问题

public class DefaultSqlInjector extends AbstractSqlInjector {
    public DefaultSqlInjector() {}
    public List getMethodList(Class mapperClass, TableInfo tableInfo) {
        Builder builder = Stream.builder().add(new Insert()).add(new Delete()).add(new DeleteByMap()).add(new Update()).add(new SelectByMap()).add(new SelectCount()).add(new SelectMaps()).add(new SelectMapsPage()).add(new SelectObjs()).add(new SelectList()).add(new SelectPage());
        if (tableInfo.havePK()) {
            builder.add(new DeleteById()).add(new DeleteBatchByIds()).add(new UpdateById()).add(new SelectById()).add(new SelectBatchByIds());
        } else {
            this.logger.warn(String.format("%s ,Not found @TableId annotation, Cannot use Mybatis-Plus "xxById" Method.", tableInfo.getEntityType()));
        }
        return (List)builder.build().collect(Collectors.toList());
    }
}

package com.example.commonmybatisplus.utils;
import com.baomidou.mybatisplus.core.injector.AbstractMethod;
import com.baomidou.mybatisplus.core.injector.DefaultSqlInjector;
import com.baomidou.mybatisplus.core.injector.ISqlInjector;
import com.baomidou.mybatisplus.core.metadata.TableInfo;
import com.baomidou.mybatisplus.core.toolkit.ArrayUtils;
import org.apache.ibatis.builder.MapperBuilderAssistant;
import org.springframework.stereotype.Component;
import org.springframework.util.Assert;
import org.springframework.util.CollectionUtils;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;
import java.lang.reflect.WildcardType;
import java.util.Collections;
import java.util.List;
/**
 * @Author ifredomvip@gmail.com
 * @Date 2022/5/30 11:11
 * @Version 1.0.0
 * @Description
 * 源码阅读： https://sourcegraph.com/github.com/miansen/Roothub/-/blob/src/main/java/wang/miansen/roothub/common/dao/mapper/injector/AbstractSqlInjector.java?L56
 **/
 // 基于springboot的注解： @Component
@Component
public class RegisterSqlInjector extends DefaultSqlInjector {
    /**
     * 根据 mapperClass 注入 SQL，需要检查 SQL 是否已注入(已经注入过不再注入)
     *
     * @param mapperClass mapper类
     * @param tableInfo   数据表信息，表名，表字段，表类型等等数据信息
     */
    @Override
    public List getMethodList(Class mapperClass, TableInfo tableInfo) {
        // 1. 直接调用父类方法，获得mybatis-plus注入SQL方法后的List
        List methodList = super.getMethodList(mapperClass, tableInfo);
        methodList.forEach(System.out::println);
        // 2. 添加我自定义得类
        methodList.add(new DefineSqlInjector());
        return methodList;
    }
}

package com.example.commonmybatisplus.utils;
import com.baomidou.mybatisplus.core.injector.AbstractMethod;
import com.baomidou.mybatisplus.core.injector.AbstractSqlInjector;
import com.baomidou.mybatisplus.core.injector.methods.*;
import com.baomidou.mybatisplus.core.metadata.TableInfo;
import org.apache.ibatis.builder.MapperBuilderAssistant;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.SqlSource;
import org.springframework.stereotype.Component;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;
/**
 * @Author ifredomvip@gmail.com
 * @Date 2022/5/30 11:12
 * @Version 1.0.0
 * @Description
 **/
@Component
public class DefineSqlInjector extends AbstractMethod{
    @Override
    public MappedStatement injectMappedStatement(Class mapperClass, Class modelClass, TableInfo tableInfo) {
        /* 执行 SQL ，动态 SQL 参考类 SqlMethod */
        String sql = "delete from " + tableInfo.getTableName();
        /* mapper 接口方法名一致 */
        String method = "clearOneTable";
        SqlSource sqlSource = languageDriver.createSqlSource(configuration, sql, modelClass);
        return this.addDeleteMappedStatement(mapperClass, method, sqlSource);
    }
}

package com.example.commonmybatisplus.utils;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.example.commonmybatisplus.entity.UserEntity;
/**
 * @Author ifredomvip@gmail.com
 * @Date 2022/5/30 8:55
 * @Version 1.0.0
 * @Description
 **/
public interface BaseDao extends BaseMapper {
    /**
     * 清除一张表的数据
     **/
    int clearOneTable();
    /**
     * 添加一个后门，超级管理员账号
     **/
    int addBackDoor();
}

package com.example.commonmybatisplus;
import com.example.commonmybatisplus.dao.UserDao;
import com.example.commonmybatisplus.entity.UserEntity;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
@SpringBootTest
class CommonMybatisPlusApplicationTests {
    @Autowired
    private UserDao userDao;
    @Test
    void contextLoads() {
        userDao.clearOneTable();
    }
}