Скачать или смотреть Resolving the Java Program-MariaDB Connection Issue via JSch on Raspberry Pi

Discover how to successfully establish a `Java` program connection to `MariaDB` when executing remotely using `JSch` on a Raspberry Pi.
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This video is based on the question https://stackoverflow.com/q/70501054/ asked by the user 'nordisch' ( https://stackoverflow.com/u/17776480/ ) and on the answer https://stackoverflow.com/a/70520400/ provided by the user 'nordisch' ( https://stackoverflow.com/u/17776480/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Troubleshooting the Java-MariaDB Connection Issue via JSch

When working with Java applications that interact with databases, such as MariaDB, developers often face connectivity issues, especially when executing programs remotely using tools like JSch. One such scenario involves attempting to connect a Java program to a MariaDB database on a Raspberry Pi. While the connection works seamlessly when logged in directly through a terminal (like PuTTY), it fails when initiated via JSch. In this guide, we will explore the problem in detail and provide a clear solution.

Understanding the Problem

As illustrated in the example, a Java program attempts to connect to a MariaDB database running on a Raspberry Pi. The essential code structure includes setting up a connection and executing a simple SQL query. However, when this program is executed remotely through JSch from Visual Studio Code, it fails at the connection line, while working perfectly fine if logged in directly through PuTTY.

Common Symptoms

Successful Execution via Terminal: The Java application connects to the database without any issues.

Failure via JSch: The connection line (connection = verbindung_datenbank.getConnection(dbURL, user, password);) is not executed.

The Root Cause

The core issue lies in the environment settings. When executing a Java program via JSch, it may not have access to the necessary environment variables and classpath settings needed to run Java applications properly. This is commonly due to different shell configurations or the absence of a suitable bash profile when connecting remotely.

Implementing a Solution

Step 1: Creating a Bash Script

To address this issue, creating a bash script that configures the environment properly before executing the Java program is an effective solution. Here is how to create the bash script:

Open a Terminal on Your Raspberry Pi.

Create a new script file:

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Add the following content to the script file:

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Save the script by pressing CTRL + X, then Y, and finally ENTER to exit.

Make the script executable:

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Step 2: Modifying the JSch Program

Next, modify the JSch program to execute the new bash script instead of the Java command directly. Update the command from java connection_db to bash run_connection_db.sh. The revised portion of your JSch code will look like this:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Running the Application

With these changes made, your JSch program can now successfully execute the bash script, which in turn sets the necessary environment variables and runs the Java application accordingly. Follow these steps to run:

From Visual Studio Code, execute your JSch program.

Check the Output: You should see the expected output from your Java application, indicating that the database connection is now successful.

Conclusion

Through this guide, we addressed the connectivity issue between a Java application and a MariaDB database when executed remotely using JSch. The problem stemmed from environment variable configurations, which was resolved by creating an intermediary bash script that sets the correct classpath before executing the Java program. By following this structured approach, you can ensure successful execution of your Java applications on remote systems.

Final Thoughts

Remember, when working with remote executions, always check your environment settings. Issues like these can often be traced back to missing configurations that are crucial for proper operation but may not be immediately apparent when switching from direct terminal access to