尝试连接到 android 上的 mongodb 数据库时出错

Question

The error that I am getting is

com.mongodb.MongoTimeoutException: Timed out after 30000 ms while waiting to connect. Client view of cluster state is {type=UNKNOWN, servers=[{address=localhost:27017, type=UNKNOWN, state=CONNECTING, exception={com.mongodb.MongoSocketOpenException: Exception opening socket}, caused by {java.net.ConnectException: failed to connect to localhost/127.0.0.1 (port 27017) from /127.0.0.1 (port 43950) after 10000ms: isConnected failed: ECONNREFUSED (Connection refused)}, caused by {android.system.ErrnoException: isConnected failed: ECONNREFUSED (Connection refused)}}]

I'm assuming the issue here is that the AVD is using the same IP as my computer, but if I try to change it in the settings of the AVD it fails to connect to androidWifi. (I tried changing it to 10.0.2.2, because that's the solution I found on annother stackoverflow post, it didn't work.)

If it matters, my code looks like this:

    MongoClient client = MongoClients.create("mongodb://localhost:27017");
    MongoDatabase db = client.getDatabase("userData");
    MongoCollection<Document> users = db.getCollection("users");

    Document user = new Document("name", "user").append("password", "pass");

    users.insertOne(user);

Answer 1

Adding this answer for posterity - the reason why this error occurs is because in the line:

 MongoClient client = MongoClients.create("mongodb://localhost:27017");

the DB address is being set to the ANDROID'S localhost and NOT the PC's that's hosting the AVD. To fix this, find your ipv4 address using the command ipconfig in CMD, then, when running the mongo shell type the following command: mongod --bind_ip "yourIPHere"

please do note, however that this will open your database up to external connections, if someone happens to have your internal IP address.