Question

public static ArrayList<DBObject> retrieve(String dbName, String collectionName, String key, String value)
{
    ArrayList<DBObject> ar = new ArrayList();
    MongoClient mongoClient = new MongoClient(new 
    MongoClientURI("mongodb://localhost:27017"));
    @SuppressWarnings("deprecation")
    DB database = mongoClient.getDB(dbName);
    DBCollection collection = database.getCollection(collectionName);
    BasicDBObject Query = new BasicDBObject();
    Query.put(key, value);
    DBCursor cursor = collection.find(Query);
    while(cursor.hasNext()) {
        LOGGER.info(cursor.next().toString());
        ar.add(cursor.next());
    }
    LOGGER.info(ar.toString());
    return(ar);

}

这是我的类函数，它从数据库中检索数据。我需要将此数据返回给另一个类。这是正确的方法吗？如果没有，我该怎么做？

数据示例：

[
    {
    "id": "234567",
    "reportType": "Thyroid",
    "age": 21,
    "gender": "Female",
    "onThyroxine": false,
    "onAntiThyroideMed": false,
    "sick": false,
    "pregnant": false,
    "recentThryoidSurgery": false,
    "lithium": false,
    "goitre": false,
    "tumor": false,
    "hypopituitary": false,
    "i131Treatment": false,
    "fti": 11,
    "tbg": 123,
    "tt4": 23,
    "t3": 120,
    "t4U": 12,
    "tsh": 120
    }
]

Answer 1

由于您需要返回查询结果中找到的所有文档，因此可以使用DBCursor的toArray()方法。

参考 - http://api.mongodb.com/java/current/com/mongodb/DBCursor.html

基本上这个 -

public static ArrayList<DBObject> retrieve(String dbName, String collectionName, String key, String value) {
    MongoClient mongoClient = new MongoClient(new 
    MongoClientURI("mongodb://localhost:27017"));
    @SuppressWarnings("deprecation")
    DB database = mongoClient.getDB(dbName);
    DBCollection collection = database.getCollection(collectionName);
    BasicDBObject Query = new BasicDBObject();
    Query.put(key, value);
    return collection.find(Query).toArray();    
}

Answer 2

您可以在需要引用此数据的另一个类中创建此类的对象。

您可以在需要此数据的类中调用此类对象的.retrieve()方法。

Answer 3

编辑代码：

public static List<DBObject> retrieve(String dbName, String collectionName, String key, String value)
{
    ArrayList<DBObject> ar = new ArrayList();
    MongoClient mongoClient = new MongoClient(new 
    MongoClientURI("mongodb://localhost:27017"));
    @SuppressWarnings("deprecation")
    DB database = mongoClient.getDB(dbName);
    DBCollection collection = database.getCollection(collectionName);
    BasicDBObject Query = new BasicDBObject();
    Query.put(key, value);
    //DBCursor cursor = collection.find(Query);
    List<DBObject> obj = collection.find(Query).limit(100).toArray();
    LOGGER.info(obj.toString());
    return(obj);   
}

参考瑞诗凯诗的回答，这是更新后的代码。这非常有效。

如何返回收到的mongodb数据？

3 个答案: