mybatis-plus 动态表名

一:背景

我们在查询数据库设计的时候会按一定的条件分表,我们需要根据条件拼接动态表名

在动态分表的背景下，有时候查询数据的时候需要跨表查询，那此时就需要MP在解析的时候，能够很好的自适应表格名称,进行wrapper条件查询

二:实现

MP中是通过PaginationInterceptor(分页插件)完成动态表名解析的，最终用法如下:

DynamicTableTreadLocal.INSTANCE.setTableName(GcQmUtil.getCartNumberByCartNumber(cartNumber));
QueryWrapper<QmRectifySlave> wrapper = new QueryWrapper<>();

三:pom.xml 依赖

        <mybatis-plus-boot-starter.version>3.3.1</mybatis-plus-boot-starter.version>
<!-- mybatis-plus begin -->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>${mybatis-plus-boot-starter.version}</version>
        </dependency>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-generator</artifactId>
            <version>${mybatis-plus-boot-starter.version}</version>
        </dependency>

四:配置类

package com.kexin.common.config;

import com.baomidou.mybatisplus.extension.incrementer.OracleKeyGenerator;
import com.baomidou.mybatisplus.extension.parsers.DynamicTableNameParser;
import com.baomidou.mybatisplus.extension.parsers.ITableNameHandler;
import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;
import com.baomidou.mybatisplus.extension.plugins.pagination.optimize.JsqlParserCountOptimize;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringBootConfiguration;
import org.springframework.context.annotation.Bean;

import java.util.Collections;
import java.util.HashMap;

@SpringBootConfiguration
@MapperScan("com.kexin.admin.mapper*")
public class MybatisPlusConfig {

    private static final String DYNAMIC_TABLE_PRE = "QM_RECTIFY_SLAVE";
    @Bean
    public PaginationInterceptor paginationInterceptor() {
        PaginationInterceptor paginationInterceptor = new PaginationInterceptor();
        // 设置请求的页面大于最大页后操作， true调回到首页，false 继续请求  默认false
        // paginationInterceptor.setOverflow(false);
        // 设置最大单页限制数量，默认 500 条，-1 不受限制
        // paginationInterceptor.setLimit(500);
        // 开启 count 的 join 优化,只针对部分 left join
        paginationInterceptor.setCountSqlParser(new JsqlParserCountOptimize(true));
//        paginationInterceptor.setDbType("oracle");

        // 设置请求的页面大于最大页后操作， true调回到首页，false 继续请求  默认false
        paginationInterceptor.setOverflow(false);
        // 设置最大单页限制数量，默认 500 条，-1 不受限制
        paginationInterceptor.setLimit(500);
//        // 开启 count 的 join 优化,只针对部分 left join
        paginationInterceptor.setCountSqlParser(new JsqlParserCountOptimize(true));
        DynamicTableNameParser dynamicTableNameParser = new DynamicTableNameParser();
        dynamicTableNameParser.setTableNameHandlerMap(new HashMap<String, ITableNameHandler>(2) {{
            //动态表规则-生成自己需要的动态表名
            put(DYNAMIC_TABLE_PRE, (metaObject, sql, tableName) -> DynamicTableTreadLocal.INSTANCE.getTableName());
        }});
        paginationInterceptor.setSqlParserList(Collections.singletonList(dynamicTableNameParser));

        return paginationInterceptor;
    }


    /**
     * Sequence主键自增
     *
     * @return 返回oracle自增类
     * @author
     * @date 2019/1/2
     */
    @Bean
    public OracleKeyGenerator oracleKeyGenerator(){
        return new OracleKeyGenerator();
    }
}

五:动态表名存储类

package com.kexin.common.config;

/**
 * @description: 动态表名存储类
 * @author: 巫恒强
 * @time: 2021/7/22 10:32
 */
public enum DynamicTableTreadLocal {
    INSTANCE;
    private ThreadLocal<String> tableName = new ThreadLocal<>();

    public String getTableName() {
        return tableName.get();
    }

    public void setTableName(String tableName) {
        this.tableName.set(tableName);
    }

    public void remove() {
        tableName.remove();
    }

}

六:工具类 (根据实际情况编写)

package com.kexin.common.util.gc;


import com.kexin.admin.entity.tables.QmRectifyMaster;

/**
 * @description:
 * @author: 巫恒强
 * @time: 2021/7/15 14:24
 */
public class GcQmUtil {

    public static String getCartNumberByRectifyMater(QmRectifyMaster master){
        return "QM_RECTIFY_SLAVE_"+master.getCartNumber().substring(0,2);
    }
    public static String getCartNumberByCartNumber(String cartNumber){
        return "QM_RECTIFY_SLAVE_"+cartNumber.substring(0,2);
    }
}

七:具体使用 (分页动态查询)

        DynamicTableTreadLocal.INSTANCE.setTableName(GcQmUtil.getCartNumberByCartNumber(cartNumber));
        QueryWrapper<QmRectifySlave> wrapper = new QueryWrapper<>();
        wrapper.eq("RECTIFYM_ID",rectifymId);
        IPage<QmRectifySlave> ipage = qmRectifySlaveService.page(new Page<>(page,limit),wrapper);