java - 从 mongodb java api 检索数据

Question

我在 mongodb 数据库中有一个字段 tweets，其中包含存储的 tweet 的几个特征。用户字段之一，包含有关发布推文的用户的信息。我想检索给定的用户 ID，以及存储在数据库中的用户的一些其他信息。数据库结构:

_id
tweet_info
user
      id
      description
      default_profile

我想要用用户 ID 来检索字段描述和 default_profile。我应该在这里执行什么查询？到目前为止我的代码:

MongoClient mongoClient = new MongoClient("..", 27017);
    DB db = mongoClient.getDB("...");
    DBCollection coll = db.getCollection("...");


    BasicDBObject query = new BasicDBObject("??,  ??);
    DBCursor  cursor = coll.find(query);
    System.out.println(cursor);
    try {
        while (cursor.hasNext()) {
             final DBObject result = cursor.next();
             Map<String, Object> value = (Map<String, Object>) result.get("user");
            System.out.println(value.get("default_profile"));
            System.out.println(value.get("description"));
            System.out.println(cursor.next());
        }
    } finally {
        cursor.close();
    }

如何在给定 user.id 的情况下检索此字段？我正在尝试的是以下内容:

 BasicDBObject query = new BasicDBObject("user.id",  975789703); // id example
    DBCursor  cursor = coll.find(query);
    System.out.println(cursor);
    try {
        while (cursor.hasNext()) {
             final DBObject result = cursor.next();
             Map<String, Object> value = (Map<String, Object>) result.get("user");
            System.out.println(value.get("default_profile"));
            System.out.println(value.get("default_profile_image"));
            System.out.println(cursor.next());
        }
    } finally {
        cursor.close();
    }

当我尝试执行如下查询时:

BasicDBObject query = new BasicDBObject("user.name", "");

它返回所有用户。几分钟后我收到消息:

Cursor id=0, ns=iti_se.cms, query={ "user.id" : 507813128}, numIterated=0, limit=20, 
readPreference=primary
Exception in thread "main" com.mongodb.MongoException: interrupted at shutdown
 at com.mongodb.MongoException.parse(MongoException.java:82)
 at com.mongodb.DBApiLayer$MyCollection.__find(DBApiLayer.java:314)
 at com.mongodb.DBApiLayer$MyCollection.__find(DBApiLayer.java:295)
 at com.mongodb.DBCursor._check(DBCursor.java:368)
 at com.mongodb.DBCursor._hasNext(DBCursor.java:459)
at com.mongodb.DBCursor.hasNext(DBCursor.java:484)
at twitter4j.examples.tweets.UpdateStatus.default_image(UpdateStatus.java:94)
at twitter4j.examples.tweets.UpdateStatus.main(UpdateStatus.java:112)

Java 结果:1

Answer 1

试试这个:

BasicDBObject query = new BasicDBObject("user.id",  userId);