JAVA代码实现MongoDB动态条件之分页查询

一、使用QueryByExampleExecutor

1. 继承MongoRepository

public interface StudentRepository extends MongoRepository<Student, String> { }

2. 代码实现

使用ExampleMatcher匹配器-----只支持字符串的模糊查询，其他类型是完全匹配 Example封装实体类和匹配器 使用QueryByExampleExecutor接口中的findAll方法

public Page<Student> getListWithExample(StudentReqVO studentReqVO) { Sort sort = Sort.by(Sort.Direction.DESC, 'createTime'); Pageable pageable = PageRequest.of(studentReqVO.getPageNum(), studentReqVO.getPageSize(), sort); Student student = new Student(); BeanUtils.copyProperties(studentReqVO, student); //创建匹配器，即如何使用查询条件 ExampleMatcher matcher = ExampleMatcher.matching() //构建对象 .withStringMatcher(ExampleMatcher.StringMatcher.CONTAINING) //改变默认字符串匹配方式：模糊查询 .withIgnoreCase(true) //改变默认大小写忽略方式：忽略大小写 .withMatcher('name', ExampleMatcher.GenericPropertyMatchers.contains()) //采用“包含匹配”的方式查询 .withIgnorePaths('pageNum', 'pageSize'); //忽略属性，不参与查询 //创建实例 Example<Student> example = Example.of(student, matcher); Page<Student> students = studentRepository.findAll(example, pageable); return students;}

缺点：

不支持过滤条件分组。即不支持过滤条件用 or(或) 来连接，所有的过滤条件，都是简单一层的用 and(并且) 连接 不支持两个值的范围查询，如时间范围的查询

二、MongoTemplate结合Query

实现一：使用Criteria封装查询条件

public Page<Student> getListWithCriteria(StudentReqVO studentReqVO) { Sort sort = Sort.by(Sort.Direction.DESC, 'createTime'); Pageable pageable = PageRequest.of(studentReqVO.getPageNum(), studentReqVO.getPageSize(), sort); Query query = new Query(); //动态拼接查询条件 if (!StringUtils.isEmpty(studentReqVO.getName())){ Pattern pattern = Pattern.compile('^.*' + studentReqVO.getName() + '.*$', Pattern.CASE_INSENSITIVE); query.addCriteria(Criteria.where('name').regex(pattern)); } if (studentReqVO.getSex() != null){ query.addCriteria(Criteria.where('sex').is(studentReqVO.getSex())); } if (studentReqVO.getCreateTime() != null){ query.addCriteria(Criteria.where('createTime').lte(studentReqVO.getCreateTime())); } //计算总数 long total = mongoTemplate.count(query, Student.class); //查询结果集 List<Student> studentList = mongoTemplate.find(query.with(pageable), Student.class); Page<Student> studentPage = new PageImpl(studentList, pageable, total); return studentPage;}

实现二：使用Example和Criteria封装查询条件

public Page<Student> getListWithExampleAndCriteria(StudentReqVO studentReqVO) { Sort sort = Sort.by(Sort.Direction.DESC, 'createTime'); Pageable pageable = PageRequest.of(studentReqVO.getPageNum(), studentReqVO.getPageSize(), sort); Student student = new Student(); BeanUtils.copyProperties(studentReqVO, student); //创建匹配器，即如何使用查询条件 ExampleMatcher matcher = ExampleMatcher.matching() //构建对象 .withStringMatcher(ExampleMatcher.StringMatcher.CONTAINING) //改变默认字符串匹配方式：模糊查询 .withIgnoreCase(true) //改变默认大小写忽略方式：忽略大小写 .withMatcher('name', ExampleMatcher.GenericPropertyMatchers.contains()) //标题采用“包含匹配”的方式查询 .withIgnorePaths('pageNum', 'pageSize'); //忽略属性，不参与查询 //创建实例 Example<Student> example = Example.of(student, matcher); Query query = new Query(Criteria.byExample(example)); if (studentReqVO.getCreateTime() != null){ query.addCriteria(Criteria.where('createTime').lte(studentReqVO.getCreateTime())); } //计算总数 long total = mongoTemplate.count(query, Student.class); //查询结果集 List<Student> studentList = mongoTemplate.find(query.with(pageable), Student.class); Page<Student> studentPage = new PageImpl(studentList, pageable, total); return studentPage;}

缺点：

不支持返回固定字段

三、MongoTemplate结合BasicQuery

BasicQuery是Query的子类 支持返回固定字段

public Page<Student> getListWithBasicQuery(StudentReqVO studentReqVO) { Sort sort = Sort.by(Sort.Direction.DESC, 'createTime'); Pageable pageable = PageRequest.of(studentReqVO.getPageNum(), studentReqVO.getPageSize(), sort); QueryBuilder queryBuilder = new QueryBuilder(); //动态拼接查询条件 if (!StringUtils.isEmpty(studentReqVO.getName())) { Pattern pattern = Pattern.compile('^.*' + studentReqVO.getName() + '.*$', Pattern.CASE_INSENSITIVE); queryBuilder.and('name').regex(pattern); } if (studentReqVO.getSex() != null) { queryBuilder.and('sex').is(studentReqVO.getSex()); } if (studentReqVO.getCreateTime() != null) { queryBuilder.and('createTime').lessThanEquals(studentReqVO.getCreateTime()); } Query query = new BasicQuery(queryBuilder.get().toString()); //计算总数 long total = mongoTemplate.count(query, Student.class); //查询结果集条件 BasicDBObject fieldsObject = new BasicDBObject(); //id默认有值，可不指定 fieldsObject.append('id', 1) //1查询，返回数据中有值；0不查询，无值.append('name', 1); query = new BasicQuery(queryBuilder.get().toString(), fieldsObject.toJson()); //查询结果集 List<Student> studentList = mongoTemplate.find(query.with(pageable), Student.class); Page<Student> studentPage = new PageImpl(studentList, pageable, total); return studentPage;}

四、MongoTemplate结合Aggregation

使用Aggregation聚合查询 支持返回固定字段 支持分组计算总数、求和、平均值、最大值、最小值等等

public Page<Student> getListWithAggregation(StudentReqVO studentReqVO) { Sort sort = Sort.by(Sort.Direction.DESC, 'createTime'); Pageable pageable = PageRequest.of(studentReqVO.getPageNum(), studentReqVO.getPageSize(), sort); Integer pageNum = studentReqVO.getPageNum(); Integer pageSize = studentReqVO.getPageSize(); List<AggregationOperation> operations = new ArrayList<>(); if (!StringUtils.isEmpty(studentReqVO.getName())) { Pattern pattern = Pattern.compile('^.*' + studentReqVO.getName() + '.*$', Pattern.CASE_INSENSITIVE); Criteria criteria = Criteria.where('name').regex(pattern); operations.add(Aggregation.match(criteria)); } if (null != studentReqVO.getSex()) { operations.add(Aggregation.match(Criteria.where('sex').is(studentReqVO.getSex()))); } long totalCount = 0; //获取满足添加的总页数 if (null != operations && operations.size() > 0) { Aggregation aggregationCount = Aggregation.newAggregation(operations); //operations为空，会报错 AggregationResults<Student> resultsCount = mongoTemplate.aggregate(aggregationCount, 'student', Student.class); totalCount = resultsCount.getMappedResults().size(); } else { List<Student> list = mongoTemplate.findAll(Student.class); totalCount = list.size(); } operations.add(Aggregation.skip((long) pageNum * pageSize)); operations.add(Aggregation.limit(pageSize)); operations.add(Aggregation.sort(Sort.Direction.DESC, 'createTime')); Aggregation aggregation = Aggregation.newAggregation(operations); AggregationResults<Student> results = mongoTemplate.aggregate(aggregation, 'student', Student.class); //查询结果集 Page<Student> studentPage = new PageImpl(results.getMappedResults(), pageable, totalCount); return studentPage;}

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