三種方法中均需要注意，建立client時，會連線認證資料庫，而不是儲存資料的資料庫。

方法一:new MongoClient(new MongoClientURI(url))
注意這種方法中，url中不要跟儲存資料的資料庫名字。

String url = "mongodb://username:password@host:port";
MongoClient mongoClient = new MongoClient(new MongoClientURI(url));

方法二：new MongoClient(serverAddress, Arrays.asList(credential))
此方法已經deprecated。

MongoCredential credential = MongoCredential.createCredential(username, 認證資料庫名稱，通常為"admin", password.toCharArray());
ServerAddress serverAddress = new ServerAddress(host, port);
MongoClient mongoClient = new MongoClient(serverAddress, Arrays.asList(credential));

方法三：new MongoClient(serverAddress, credential, options)

MongoCredential credential = MongoCredential.createCredential(username, 認證資料庫名稱，通常為"admin", password.toCharArray());
MongoClientOptions options = new MongoClientOptions.Builder().build();
ServerAddress serverAddress = new ServerAddress(host, port);
MongoClient mongoClient = new MongoClient(serverAddress, credential, options);
 

取資料以驗證是否連線成功

import static com.mongodb.client.model.Filters.eq;
MongoDatabase db = mongoClient.getDatabase(db_name);
MongoCollection<Document> collection = db.getCollection("表名");
Document doc = collection.find(eq("列名", 值)).first();
if (doc != null)
    System.out.println(doc.toJson());
mongoClient.close();