Robot Management API: Add, Delete, and Update Robots

This code defines a Java Servlet named 'Robot' that handles HTTP POST requests to the '/welcome' endpoint. It uses the 'action' parameter to determine the requested operation: 'addRobot', 'deleteRobot', or 'changeRobot'.

• addRobot: Inserts a new robot record into the 'robot' table with provided details. The request should include parameters: 'robotname', 'robotweight', and 'robotsize'.
• deleteRobot: Deletes a robot record from the 'robot' table using the provided 'robotID'.
• changeRobot: Updates an existing robot record in the 'robot' table with the provided information. The request should include parameters: 'robotID1', 'robotname1', 'robotweight1', and 'robotsize1'.

The code uses PreparedStatements to execute SQL queries, ensuring parameterization and preventing SQL injection vulnerabilities. It utilizes a DBConnected class (not shown in the provided code) to establish and manage the database connection.

The 'action' parameter is obtained using the 'req.getParameter('action')' method, which retrieves the value of the 'action' parameter from the HTTP request. Based on the 'action' value, the code performs the corresponding database operation and redirects the user to 'welcome.jsp' after successful completion. The code also includes exception handling to log any potential errors during database operations.