Can't connect to oracle database outside container with jdbc - oracle

Question

I created a container for an Oracle Express database following these instructions, with the following command:
docker run -d -e ORACLE_PWD="root" --name testdb -p 5500:5500 -p 8080:8080 -p 1521:1521 container-registry.oracle.com/database/express:21.3.0-xe
What does work
I managed to access the database from within the container with this command:
docker exec -it testdb sqlplus system/root#//localhost:1521/XE
I also managed to access to access the Oracle Enterprise Manager on localhost:5500/em using these credentials:
Username: system
Password: root
Container Name: <blank>
What doesn't work
I fail to connect using IntelliJ, and therefore the underlying JDBC library. I use the following options:
For Password, I used root again, the JDBC URL is as follows:
jdbc:oracle:thin:#localhost:1521:XE
When I click on Test connection, IntelliJ tries to connect for about a minute, before showing the following error

Answer 1

I did a test on my MacOS
# fire up the database. Hint, use gvenzl images instead. Much faster!
docker run -d -e ORACLE_PWD="root" --name testdb -p 5500:5500 -p 8081:8080 -p 1521:1521 container-registry.oracle.com/database/express:21.3.0-xe
# I have sqlplus installed locally on my MacOS
echo 'select dummy from dual;' | sqlplus -S system/"root"#localhost/XE
D
-
X
echo 'select dummy from dual;' | sqlplus -S system/"root"#localhost:XE
ERROR:
ORA-12545: Connect failed because target host or object does not exist
SP2-0306: Invalid option.
# so, how is JDBC behaving taking the connect string as argument
java -cp .:./ojdbc8-19.6.0.0.jar OracleJDBC "jdbc:oracle:thin:#localhost:1521:XE"
X
java -cp .:./ojdbc8-19.6.0.0.jar OracleJDBC "jdbc:oracle:thin:#localhost:XE"
java.sql.SQLRecoverableException: IO Error: Invalid number format for port number
java -cp .:./ojdbc8-19.6.0.0.jar OracleJDBC "jdbc:oracle:thin:#localhost/XE"
X
Note. Port is not needed, defaults to 1521
cat OracleJDBC.java
import java.sql.DriverManager;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.ResultSet;
public class OracleJDBC {
public static void main(String[] argv) {
try {
Class.forName("oracle.jdbc.driver.OracleDriver");
} catch (ClassNotFoundException e) {
System.out.println("Where is your Oracle JDBC Driver?");
e.printStackTrace();
return;
}
Connection connection = null;
String query = "select dummy from dual";
try {
connection = DriverManager.getConnection(argv[0], "system","root");
Statement stmt = connection.createStatement();
ResultSet rows = stmt.executeQuery(query);
while (rows.next()) {
System.out.println(rows.getString("dummy"));
}
} catch (SQLException e) {
e.printStackTrace();
}
}
}
I cannot explain why you get the error. Can it be the JDBC version you are using? I have just proven, your connection should work. That said, you are not supposed to connect using the SID construct (:SID) anymore. You will hit the root-container and not where you are supposed to store your data - in a pluggable database. The express-edition comes with the default pluggable database "XEPDB1".
echo 'select name from v$pdbs;' | sqlplus -S system/"root"#localhost/XE
NAME
------------------------------
PDB$SEED
XEPDB1
This should be your connect string:
echo 'select dummy from dual;' | sqlplus -S system/"root"#localhost/XEPDB1
D
-
X
From here you create your app schema and user so you no longer will use the power-user 'system'.
Best of luck!

Answer 2

I worked perfectly well when I used the same configuration, but with this image instead of the official one.
Thanks to Bjarte Brandt for pointing me to this image.