java.sql.SQLRecoverableException: IO 错误: The Network Adapter could not establish the connection

This exception is thrown when the Java program encounters an IO error while trying to establish a database connection. The error message specifically indicates that the network adapter (which is responsible for connecting to the database server) was unable to establish a connection.

Possible causes for this error include:

1. The database server is not running or is unavailable.
2. The network connection between the Java program and the database server is down or unstable.
3. The database server is configured to reject incoming connections from the Java program.
4. The database server is overloaded and unable to accept new connections.

To resolve this error, you should first verify that the database server is running and available. You can also try restarting the database server and/or the Java program to see if that resolves the issue. If the problem persists, you may need to check the network connection between the Java program and the database server, and ensure that the database server is properly configured to accept incoming connections from the Java program.