You might get errors while configuring a JDBC connection. If you are using MySQL, and the connection URL is incorrect, or the MySQL database is not running, the following error message is generated:
Communications link failure
If you are using Oracle database, some possible connection configuration errors are listed below:
IO exception: The Network Adapter could not establish the connection
IO exception: Connection refused
The The Network Adapter could not establish the connection exception is caused by one or more of the following configuration errors:
1. The database host name, port number, or database instance name is wrong.
2. The database
TNSListener
has not been started. TheTNSListener
may be started with thelsnrctl
utility.
C:\>lsnrctl start
The Connection refused exception is caused by one or more of the following configuration errors:
1. The database SID specified is incorrect.
2. The database instance has not been started. To start the database instance...