JAVA代码实现MongoDB动态条件之分页查询

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 {

}

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 getListWithExample(Sthttp://udentReqVO 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 example = Example.of(student, matcher);

Page 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 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 studentList = mongoTemplate.find(query.with(pageable), Student.class);

Page studentPage = new PageImpl(studentList, pageable, total);

return studentPage;

}

实现二：使用Example和Criteria封装查询条件

public Page 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 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 studentList = mongoTemplate.find(query.with(pageable), Student.class);

Page 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 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 studentList = mongoTemplate.find(query.with(pageable), Student.class);

Page 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 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 http://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 resultsCount = mongoTemplate.aggregate(aggregationCount, "student", Student.class);

totalCount = resultsCount.getMappedResults().size();

} else {

List 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 results = mongoTemplate.aggregate(aggregation, "student", Student.class);

//查询结果集

Page studentPage = new PageImpl(results.getMappedResults(), pageable, totalCount);

return studentPage;

}

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