java中Mongo

1.  query.fields().include("idfa").include("imei").include("id").include("os");  返回数据中包含这几个字段

2.

①
List<Criteria> criterias = new ArrayList<>();

criterias.add(Criteria.where("time").gt("2017-09-20 10:02:26"));

criterias.add(Criteria.where("time").lt("2017-09-27 10:02:26"));

criterias.add(Criteria.where("imei").is("9686854123"));

query.addCriteria(new Criteria().andOperator(criterias.toArray(new Criteria[0])));

②
toArray解释

public <T> T[] toArray(T[] a) {   

        if (a.length < size)   

            a = (T[])java.lang.reflect.Array.   

                newInstance(a.getClass().getComponentType(), size);   

            System.arraycopy(elementData, 0, a, 0, size);  

　　　  if (a.length > size)   

                a[size] = null;  

            return a;   

    }  

　　由①得出如下查询语句

{ "channel" : "jinritoutiao" , 
　　"$and" : [ { "imei" : "96868541236"} , 
　　　　　　　　 { "time" : { "$lt" : "2017-09-27 10:02:26"}} , 
　　　　　　　　 { "time" : { "$gt" : "2017-09-20 10:02:26"}}
　　　　　　　]
}

3. 

query.addCriteria(Criteria.where(“Key”).is(”Value“));

从下面源码可以看出上面中的key不能是重复的值


public Query addCriteria(CriteriaDefinition criteriaDefinition) {
        CriteriaDefinition existing = (CriteriaDefinition)this.criteria.get(criteriaDefinition.getKey());
        String key = criteriaDefinition.getKey();
        if (existing == null) {
            this.criteria.put(key, criteriaDefinition);
            return this;
        } else {
            throw new InvalidMongoDbApiUsageException("Due to limitations of the com.mongodb.BasicDBObject, you can't add a second '" + key + "' criteria. " + "Query already contains '" + existing.getCriteriaObject() + "'.");
        }
    }