一、使用QueryByExampleExecutor

1. 繼承MongoRepository

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

2. 代碼實現

使用ExampleMatcher匹配器-----只支持字符串的模糊查詢，其他類型是完全匹配 Example封裝實體類和匹配器 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); //創建匹配器，即如何使用查詢條件 ExampleMatcher matcher = ExampleMatcher.matching() //構建對象 .withStringMatcher(ExampleMatcher.StringMatcher.CONTAINING) //改變默認字符串匹配方式：模糊查詢 .withIgnoreCase(true) //改變默認大小寫忽略方式：忽略大小寫 .withMatcher('name', ExampleMatcher.GenericPropertyMatchers.contains()) //采用“包含匹配”的方式查詢 .withIgnorePaths('pageNum', 'pageSize'); //忽略屬性，不參與查詢 //創建實例 Example<Student> example = Example.of(student, matcher); Page<Student> students = studentRepository.findAll(example, pageable); return students;}

缺點：

不支持過濾條件分組。即不支持過濾條件用 or(或) 來連接，所有的過濾條件，都是簡單一層的用 and(并且) 連接 不支持兩個值的范圍查詢，如時間范圍的查詢

二、MongoTemplate結合Query

實現一：使用Criteria封裝查詢條件

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(); //動態拼接查詢條件 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())); } //計算總數 long total = mongoTemplate.count(query, Student.class); //查詢結果集 List<Student> studentList = mongoTemplate.find(query.with(pageable), Student.class); Page<Student> studentPage = new PageImpl(studentList, pageable, total); return studentPage;}

實現二：使用Example和Criteria封裝查詢條件

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); //創建匹配器，即如何使用查詢條件 ExampleMatcher matcher = ExampleMatcher.matching() //構建對象 .withStringMatcher(ExampleMatcher.StringMatcher.CONTAINING) //改變默認字符串匹配方式：模糊查詢 .withIgnoreCase(true) //改變默認大小寫忽略方式：忽略大小寫 .withMatcher('name', ExampleMatcher.GenericPropertyMatchers.contains()) //標題采用“包含匹配”的方式查詢 .withIgnorePaths('pageNum', 'pageSize'); //忽略屬性，不參與查詢 //創建實例 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())); } //計算總數 long total = mongoTemplate.count(query, Student.class); //查詢結果集 List<Student> studentList = mongoTemplate.find(query.with(pageable), Student.class); Page<Student> studentPage = new PageImpl(studentList, pageable, total); return studentPage;}

缺點：

不支持返回固定字段

三、MongoTemplate結合BasicQuery

BasicQuery是Query的子類 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(); //動態拼接查詢條件 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()); //計算總數 long total = mongoTemplate.count(query, Student.class); //查詢結果集條件 BasicDBObject fieldsObject = new BasicDBObject(); //id默認有值，可不指定 fieldsObject.append('id', 1) //1查詢，返回數據中有值；0不查詢，無值.append('name', 1); query = new BasicQuery(queryBuilder.get().toString(), fieldsObject.toJson()); //查詢結果集 List<Student> studentList = mongoTemplate.find(query.with(pageable), Student.class); Page<Student> studentPage = new PageImpl(studentList, pageable, total); return studentPage;}

四、MongoTemplate結合Aggregation

使用Aggregation聚合查詢 支持返回固定字段 支持分組計算總數、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; //獲取滿足添加的總頁數 if (null != operations && operations.size() > 0) { Aggregation aggregationCount = Aggregation.newAggregation(operations); //operations為空，會報錯 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); //查詢結果集 Page<Student> studentPage = new PageImpl(results.getMappedResults(), pageable, totalCount); return studentPage;}

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