网络是通的，但是jdbc提示The Network Adapter could not establish the connection

The "The Network Adapter could not establish the connection" error in the context of JDBC usually occurs when there is a problem connecting to the database server. This error message indicates that the network is functioning properly, but there is an issue with the configuration or availability of the database server.

There can be several reasons for this error, including:
1. Incorrect IP address: Ensure that you have entered the correct IP address of the database server in your JDBC connection configuration.
2. Firewall restrictions: Check if there are any firewall restrictions that are blocking the connection to the database server. Make sure that the required ports are open and accessible.
3. Database server not running: Verify that the database server is up and running properly. If not, start the server and try establishing the connection again.
4. Incorrect database credentials: Double-check the username and password used to connect to the database. Make sure they are correct and have the necessary permissions.
5. Network connectivity issues: Check for any network connectivity issues between your application and the database server. Ensure that there are no network interruptions or connectivity problems.

To resolve this issue:
1. Verify the IP address or hostname of the database server and ensure it is correct.
2. Check the firewall settings to ensure that the required ports are open for database connections.
3. Make sure that the database server is running and accessible.
4. Double-check the database credentials used for the connection.
5. Troubleshoot any network connectivity issues that may be causing the problem.