MongodbTemplate的查询操作

Class类

@Document(collection = "class")public class Class {    private String classId;    private String teacher;    private List<Student> Students;    public String getClassId() {        return classId;    }    public void setClassId(String classId) {        this.classId = classId;    }    public String getTeacher(){        return teacher;    }    public void setTeacher(String teacher){        this.teacher = teacher;    }    public List<Student> getStudents() {        return Students;    }    public void setStudents(List<Student> Students) {        this.Students = Students;    }    @Override    public String toString() {        return "Class [classId=" + classId + ", Students=" + Students + "]";    }}

查询满足条件的数据

Query query = Query.query(Criteria.where("classId").is("1"));List<Class> classs = mongoTemplate.find(query,Class.class,"class");System.out.println(classs);

查询满足条件的第一条数据

Query query = Query.query(Criteria.where("classId").is("1"));List<Class> classs = mongoTemplate.findOne(query,Class.class,"class");System.out.println(classs);

筛选要查询的字段（id字段不查出来）

DBObject dbObject = new BasicDBObject();dbObject.put("classId", "1");DBObject fieldObject = new BasicDBObject();fieldObject.put("_id", false);Query query = new BasicQuery(dbObject, fieldObject);List<HashMap> classs = mongoTemplate.find(query,HashMap.class,"class");System.out.println(classs);

当然也可以不使用HashMap,而使用自己封装的dto，那么只会查询出dto中的字段。
查询结果排序

DBObject dbObject = new BasicDBObject();dbObject.put("classId", "1");DBObject fieldObject = new BasicDBObject();fieldObject.put("_id", false);Query query = new BasicQuery(dbObject);query.with(new Sort(Direction.ASC,"classId"));List<HashMap> classs = mongoTemplate.find(query,HashMap.class,"class");System.out.println(classs);

多字段排序

DBObject dbObject = new BasicDBObject();dbObject.put("classId", "1");DBObject fieldObject = new BasicDBObject();fieldObject.put("_id", false);Query query = new BasicQuery(dbObject);List<Sort.Order> orders = new ArrayList<>();orders.add(new Sort.Order(Direction.DESC, "classId"));orders.add(new Sort.Order(Direction.DESC, "teacher"));query.with(new Sort(orders));List<HashMap> classs = mongoTemplate.find(query,HashMap.class,"class");System.out.println(classs);

查询结果分页

int pageNum = 1;int pageSize = 10;DBObject dbObject = new BasicDBObject();dbObject.put("classId", "1");DBObject fieldObject = new BasicDBObject();fieldObject.put("_id", false);Query query = new BasicQuery(dbObject,fieldObject);List<Sort.Order> orders = new ArrayList<>();orders.add(new Sort.Order(Direction.ASC, "classId"));orders.add(new Sort.Order(Direction.DESC, "teacher"));query.with(new Sort(orders));query.skip(pageSize*(pageNum-1)).limit(pageSize);List<HashMap> classs = mongoTemplate.find(query,HashMap.class,"class");System.out.println(classs);

还有一种通过Morphia框架的做法：

int pageNum = 1;int pageSize = 10;DBObject dbObject = new BasicDBObject();dbObject.put("teacher", "Mr.wang");DBObject fieldObject = new BasicDBObject();fieldObject.put("_id", false);fieldObject.put("_class", false);DBObject sortDBObject=new BasicDBObject();     sortDBObject.put("classId",1);  DBCursor result = mongoTemplate.getCollection("class")    .find(dbObject, fieldObject)    .sort(sortDBObject)    .skip(pageSize*(pageNum-1)).limit(pageSize);System.out.println(result.count());System.out.println(result.toArray());

多条件查询
我们只需要对query对象做出处理即可

Criteria criteria = new Criteria(); criteria.orOperator(Criteria.where("classId").is("2"),Criteria.where("teacher").is("Mr.wang"));criteria.andOperator(Criteria.where("classId").is("2"));query.addCriteria(criteria);