tk.mybatis 通用批量更新接口设计（方法二：通过When Case批量更新）

通过When Case批量更新

1、pom

        <!-- tk.mybatis -->
        <dependency>
            <groupId>tk.mybatis</groupId>
            <artifactId>mapper-spring-boot-starter</artifactId>
            <version>2.1.5</version>
        </dependency>

 2、注解接口 -> MyUpdateListWhenCaseMapper.java

package com.sundear.base.mybatis.tk.base;

import com.sundear.base.mybatis.tk.provider.MyUpdateListWhenCaseProvider;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.UpdateProvider;
import tk.mybatis.mapper.annotation.RegisterMapper;

import java.util.List;

/**
 * @Author: 秀丽
 * @Date: 2021/5/25 17:43
 * @description 自定义，根据id批量修改 when case 效率其实很慢
 */
@RegisterMapper
public interface MyUpdateListWhenCaseMapper<T> {

    /**
     * 自定义，根据id批量修改 when case 效率其实很慢
     * @param var1
     * @param var2
     * @return
     */
    @UpdateProvider(
            type = MyUpdateListWhenCaseProvider.class,
            method = "dynamicSQL"
    )
    int myUpdateListWhenCaseByPrimaryKey(@Param("records") List<T> var1, @Param("example") Object var2);
}

3、MyUpdateListWhenCaseProvider.java

package com.sundear.base.mybatis.tk.provider;

import com.sundear.model.exception.ServiceException;
import org.apache.ibatis.mapping.MappedStatement;
import tk.mybatis.mapper.entity.EntityColumn;
import tk.mybatis.mapper.mapperhelper.EntityHelper;
import tk.mybatis.mapper.mapperhelper.MapperHelper;
import tk.mybatis.mapper.mapperhelper.MapperTemplate;
import tk.mybatis.mapper.mapperhelper.SqlHelper;

import java.util.Set;

/**
 * @Author: 秀丽
 * @Date: 2021/5/25 17:43
 * @description 自定义，根据id批量修改
 */
public class MyUpdateListWhenCaseProvider extends MapperTemplate {

    public MyUpdateListWhenCaseProvider(Class<?> mapperClass, MapperHelper mapperHelper) {
        super(mapperClass, mapperHelper);
    }

    public String myUpdateListWhenCaseByPrimaryKey(MappedStatement ms) {
        Class<?> entityClass = this.getEntityClass(ms);
        //tableName
        String tableName = SqlHelper.getDynamicTableName(entityClass, this.tableName(entityClass), "example");

        StringBuilder sql = new StringBuilder();
        sql.append("<bind name=\"listNotEmptyCheck\" value=\"@tk.mybatis.mapper.util.OGNL@notEmptyCollectionCheck(records, '" + ms.getId() + " 方法参数为空')\"/>");
        sql.append("UPDATE ");
        sql.append(tableName);
        sql.append(" <set>");
        //实体类所有字段
        Set<EntityColumn> columnList = EntityHelper.getColumns(entityClass);
        //实体类对应id字段
        EntityColumn idColumn = columnList
                .stream()
                .filter(tempColumn -> tempColumn.isId()).findFirst()
                .orElseThrow(() -> new ServiceException("实体类id不存在"));

        columnList.stream().forEach(tempColumn -> {
            if (!tempColumn.isId()) {
                appendSetInfo(sql, tempColumn, idColumn, tableName);
            }
        });
        sql.append("</set>");
        sql.append(SqlHelper.updateByExampleWhereClause());
        return sql.toString();
    }

    /**
     * @param sql
     * @param column   update字段
     * @param idColumn id字段
     */
    private void appendSetInfo(StringBuilder sql, EntityColumn column, EntityColumn idColumn, String tableName) {
        sql.append("<trim prefix=\"`" + column.getColumn() + "` = case " + idColumn.getColumn() + "\" suffix=\"end , \">");
        sql.append("<foreach collection=\"records\" item=\"record\">");
        sql.append("<if test=\"record." + column.getEntityField().getName() + " !=null\">");
        sql.append(" WHEN #{record." + idColumn.getEntityField().getName() + "} THEN #{record." + column.getEntityField().getName() + "} ");
        sql.append("</if>");
        sql.append("<if test=\"record." + column.getEntityField().getName() + " ==null\">");
        sql.append(" WHEN #{record." + idColumn.getEntityField().getName() + "} THEN " + tableName + "." + column.getColumn() + " ");
        sql.append("</if>");
        sql.append("</foreach>");
        sql.append("</trim>");
    }

}

3、用我们的基础mapper继承我们上述接口 -》上篇文章已经创建过这个类

package com.sundear.base.mybatis;

import com.sundear.base.mybatis.tk.base.MyUpdateListForeachMapper;
import com.sundear.base.mybatis.tk.base.MyUpdateListWhenCaseMapper;

/**
 * @Author: 秀丽
 * @Date: 2021/5/8 17:41
 * @description 继承自定义的方法
 */
public interface MyBaseMapper<T> extends
        MyUpdateListForeachMapper<T>,
        MyUpdateListWhenCaseMapper<T> {
    
}

4、然后我们就可以用实体类的mapper直接调用  myUpdateListWhenCaseByPrimaryKey(List<T> var1)  方法去批量更新了list了

@Slf4j
@SpringBootTest
@RunWith(SpringRunner.class)
public class RunTest {

    @Resource
    private TbRoleMapper tbRoleMapper;
    @Resource
    private TbTestMapper tbTestMapper;


    @Test
    public void test2() {
        List<TbTest> list = new ArrayList<>();
        for (int i = 0; i < 4; i++) {
            list.add(TbTest.builder().value(""+i).id(IdWorker.getIdWorker().nextIdStr()).build());
        }
        //方式一 foreach
        tbTestMapper.myUpdateListForeachByPrimaryKey(list);

        //方式二 when case
        Example example = new Example(TbTest.class);
        example.createCriteria()
                .andIn(TbTest.Fields.id,list.stream().map(TbTest::getId).collect(Collectors.toList()));
        tbTestMapper.myUpdateListWhenCaseByPrimaryKey(list,example);
    }

}