JDBC Configuration Errors

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. The TNSListener may be started with the lsnrctl 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 connect to SQL*Plus as SYSDBA. 
    C:\>sqlplus SYS/<pwd> AS SYSDBA

At the SQL prompt, start the database instance with the startup command.

SQL>startup
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