Mybatis Plus 辅助工具类，解决in方法入参问题

Posted 2022-12-21 洛阳泰山

项目场景：

    我们再使用mybatis plus工具做java项目的时候，经常会用到mybatis plus 的LambdaQueryWrapper 或者LambdaUpdateWrapper 的in方法做查询，但是在mysql 或者pgsql的数据库中，sql 语句中in方法的参数超过1000个或者传入的集合为空的时候就会报sql错误。所以我们得在使用in的代码中做一些处理，以防止程序报错。

 @Transactional(rollbackFor = Exception.class)
    public Boolean removeRelation(List<Long> ids) 
        removeByIds(ids);
        areaService.lambdaUpdate().in(AbnormalArea::getDetectionId, ids).remove();
        return true;
    

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 问题描述

   在使用mybatis-plus,查询，修改、或者删除时，涉及到用in方法的时候，会有可能传入的in的参数超过1000个，而导致sql执行报错。

select * from user where id in (1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,162,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191,192,193,194,195,196,197,198,199,200,201,202,203,204,205,206,207,208,209,210,211,212,213,214,215,216,217,218,219,220,221,222,223,224,225,226,227,228,229,230,231,232,233,234,235,236,237,238,239,240,241,242,243,244,245,246,247,248,249,250,251,252,253,254,255,256,257,258,259,260,261,262,263,264,265,266,267,268,269,270,271,272,273,274,275,276,277,278,279,280,281,282,283,284,285,286,287,288,289,290,291,292,293,294,295,296,297,298,299,300,301,302,303,304,305,306,307,308,309,310,311,312,313,314,315,316,317,318,319,320,321,322,323,324,325,326,327,328,329,330,331,332,333,334,335,336,337,338,339,340,341,342,343,344,345,346,347,348,349,350,351,352,353,354,355,356,357,358,359,360,361,362,363,364,365,366,367,368,369,370,371,372,373,374,375,376,377,378,379,380,381,382,383,384,385,386,387,388,389,390,391,392,393,394,395,396,397,398,399,400,401,402,403,404,405,406,407,408,409,410,411,412,413,414,415,416,417,418,419,420,421,422,423,424,425,426,427,428,429,430,431,432,433,434,435,436,437,438,439,440,441,442,443,444,445,446,447,448,449,450,451,452,453,454,455,456,457,458,459,460,461,462,463,464,465,466,467,468,469,470,471,472,473,474,475,476,477,478,479,480,481,482,483,484,485,486,487,488,489,490,491,492,493,494,495,496,497,498,499,500,501,502,503,504,505,506,507,508,509,510,511,512,513,514,515,516,517,518,519,520,521,522,523,524,525,526,527,528,529,530,531,532,533,534,535,536,537,538,539,540,541,542,543,544,545,546,547,548,549,550,551,552,553,554,555,556,557,558,559,560,561,562,563,564,565,566,567,568,569,570,571,572,573,574,575,576,577,578,579,580,581,582,583,584,585,586,587,588,589,590,591,592,593,594,595,596,597,598,599,600,601,602,603,604,605,606,607,608,609,610,611,612,613,614,615,616,617,618,619,620,621,622,623,624,625,626,627,628,629,630,631,632,633,634,635,636,637,638,639,640,641,642,643,644,645,646,647,648,649,650,651,652,653,654,655,656,657,658,659,660,661,662,663,664,665,666,667,668,669,670,671,672,673,674,675,676,677,678,679,680,681,682,683,684,685,686,687,688,689,690,691,692,693,694,695,696,697,698,699,700,701,702,703,704,705,706,707,708,709,710,711,712,713,714,715,716,717,718,719,720,721,722,723,724,725,726,727,728,729,730,731,732,733,734,735,736,737,738,739,740,741,742,743,744,745,746,747,748,749,750,751,752,753,754,755,756,757,758,759,760,761,762,763,764,765,766,767,768,769,770,771,772,773,774,775,776,777,778,779,780,781,782,783,784,785,786,787,788,789,790,791,792,793,794,795,796,797,798,799,800,801,802,803,804,805,806,807,808,809,810,811,812,813,814,815,816,817,818,819,820,821,822,823,824,825,826,827,828,829,830,831,832,833,834,835,836,837,838,839,840,841,842,843,844,845,846,847,848,849,850,851,852,853,854,855,856,857,858,859,860,861,862,863,864,865,866,867,868,869,870,871,872,873,874,875,876,877,878,879,880,881,882,883,884,885,886,887,888,889,890,891,892,893,894,895,896,897,898,899,900,901,902,903,904,905,906,907,908,909,910,911,912,913,914,915,916,917,918,919,920,921,922,923,924,925,926,927,928,929,930,931,932,933,934,935,936,937,938,939,940,941,942,943,944,945,946,947,948,949,950,951,952,953,954,955,956,957,958,959,960,961,962,963,964,965,966,967,968,969,970,971,972,973,974,975,976,977,978,979,980,981,982,983,984,985,986,987,988,989,990,991,992,993,994,995,996,997,998,999,1000,1001);

---

原因分析：

   sql表达式in这个列表中，最大值是1000，当in的个数小于等于1000时，sql语句能够正常执行，超过1000.或者传入空时，则会返回错误

---

解决方案：

  需要对传入in的参数，进行处理，当参数超过1000时候，用 or in 去拼接剩余的参数。当传入为空时，传入null。我这个过程封装成了工具类，方便使用，代码如下：

import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.baomidou.mybatisplus.core.conditions.update.LambdaUpdateWrapper;
import com.baomidou.mybatisplus.core.toolkit.CollectionUtils;
import com.baomidou.mybatisplus.core.toolkit.support.SFunction;

import java.util.ArrayList;
import java.util.Collection;
import java.util.LinkedList;
import java.util.List;

/**
 * @author tarzan
 **/

public class MybatisParameterUtil 

   final static int paramNums=999;


    public static <T, F> void cutInParameter(LambdaQueryWrapper<T> wrapper, SFunction<T, ?> column, Collection<F> coll)  
        List<List<F>> list = splitList(coll, paramNums);
        if (CollectionUtils.isNotEmpty(list)) 
            if(list.size() ==1)
                wrapper.in(column, list.get(0));
            else
                wrapper.and(i -> 
                    i.in(column, list.get(0));
                    list.remove(0);
                    for (List<F> objects : list) 
                        i.or().in(column, objects);
                    
                );
            
        else
            wrapper.eq(column, null);
        
    

    public static <T, F> void cutNotInParameter(LambdaQueryWrapper<T> wrapper, SFunction<T, ?> column, Collection<F> coll)  
        List<List<F>> list = splitList(coll, paramNums);
        if (CollectionUtils.isNotEmpty(list)) 
            if(list.size() ==1)
                wrapper.notIn(column, list.get(0));
            else
                wrapper.and(i -> 
                    i.in(column, list.get(0));
                    list.remove(0);
                    for (List<F> objects : list) 
                        i.or().notIn(column, objects);
                    
                );
            
        else
            wrapper.ne(column, null);
        
    

    public static <T, F> void cutInParameter(LambdaUpdateWrapper<T> wrapper, SFunction<T, ?> column, Collection<F> coll)  
        List<List<F>> list = splitList(coll, paramNums);
        if (CollectionUtils.isNotEmpty(list)) 
            if(list.size() ==1)
                wrapper.in(column, list.get(0));
            else
                wrapper.and(i -> 
                    i.in(column, list.get(0));
                    list.remove(0);
                    for (List<F> objects : list) 
                        i.or().in(column, objects);
                    
                );
            
        else
            wrapper.eq(column, null);
        
    

    public static <T, F> void cutNotInParameter(LambdaUpdateWrapper<T> wrapper, SFunction<T, ?> column, Collection<F> coll)  
        List<List<F>> list = splitList(coll, paramNums);
        if (CollectionUtils.isNotEmpty(list)) 
            if(list.size() ==1)
                wrapper.notIn(column, list.get(0));
            else
                wrapper.and(i -> 
                    i.in(column, list.get(0));
                    list.remove(0);
                    for (List<F> objects : list) 
                        i.or().notIn(column, objects);
                    
                );
            
        else
            wrapper.ne(column, null);
        
    


    public static <F> List<List<F>> splitList(Collection<F> coll, int rows) 
        List<F> list=new LinkedList<>(coll);
        List<List<F>> newList = new ArrayList<>();
        int num = list.size();
        int i = 0;
        while (num > rows) 
            int end=i+rows;
            newList.add(list.subList(i, end));
            i = end;
            num = num - rows;
        
        if (num > 0) 
            int end=i+num;
            newList.add(list.subList(i, end));
        
        return newList;
    

工具使用：

LambdaQueryWrapper<User> userWrapper= Wrappers.lambdaQuery();
if(CollectionUtils.isNotEmpty(extensions))
                //去重
                Set<Long>  userIds=extensions.stream().map(UserExtension::getUserId).collect(Collectors.toSet());
                //调用工具类重新拼装in条件
                MybatisParameterUtil.cutInParameter(userWrapper,User::getId, new ArrayList<>(userIds));
            
userSevice.list(getWrapper(userQuery));

如果你有更好的建议、想法或者思路，可以在评论区，留言交流！！！