mybatis-plus 動態表名

一:背景

我們在查詢數據庫設計的時候會按一定的條件分表,我們需要根據條件拼接動態表名

在動態分表的背景下，有時候查詢數據的時候需要跨表查詢，那此時就需要MP在解析的時候，能夠很好的自適應表格名稱,進行wrapper條件查詢

二:實現

MP中是通過PaginationInterceptor(分頁插件)完成動態表名解析的，最終用法如下:

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

三:pom.xml 依賴

        <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:配置類

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();
        // 設置請求的頁面大於最大頁后操作， true調回到首頁，false 繼續請求  默認false
        // paginationInterceptor.setOverflow(false);
        // 設置最大單頁限制數量，默認 500 條，-1 不受限制
        // paginationInterceptor.setLimit(500);
        // 開啟 count 的 join 優化,只針對部分 left join
        paginationInterceptor.setCountSqlParser(new JsqlParserCountOptimize(true));
//        paginationInterceptor.setDbType("oracle");

        // 設置請求的頁面大於最大頁后操作， true調回到首頁，false 繼續請求  默認false
        paginationInterceptor.setOverflow(false);
        // 設置最大單頁限制數量，默認 500 條，-1 不受限制
        paginationInterceptor.setLimit(500);
//        // 開啟 count 的 join 優化,只針對部分 left join
        paginationInterceptor.setCountSqlParser(new JsqlParserCountOptimize(true));
        DynamicTableNameParser dynamicTableNameParser = new DynamicTableNameParser();
        dynamicTableNameParser.setTableNameHandlerMap(new HashMap<String, ITableNameHandler>(2) {{
            //動態表規則-生成自己需要的動態表名
            put(DYNAMIC_TABLE_PRE, (metaObject, sql, tableName) -> DynamicTableTreadLocal.INSTANCE.getTableName());
        }});
        paginationInterceptor.setSqlParserList(Collections.singletonList(dynamicTableNameParser));

        return paginationInterceptor;
    }


    /**
     * Sequence主鍵自增
     *
     * @return 返回oracle自增類
     * @author
     * @date 2019/1/2
     */
    @Bean
    public OracleKeyGenerator oracleKeyGenerator(){
        return new OracleKeyGenerator();
    }
}

五:動態表名存儲類

package com.kexin.common.config;

/**
 * @description: 動態表名存儲類
 * @author: 巫恆強
 * @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:工具類 (根據實際情況編寫)

package com.kexin.common.util.gc;


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

/**
 * @description:
 * @author: 巫恆強
 * @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:具體使用 (分頁動態查詢)

 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);