Use case :
I need to import orders from Excel file. I need to browse a Excel file.
As the attached image shows that user needs to browse the excel sheet.I was also faced the same situation. So, Assuming that request for the same has been recorded. Follow below instructions:
import org.apache.jmeter.threads.JMeterVariables;
import java.io.File;
import java.io.IOException;
File data = new File("/path/to/your/file.xlsx")
In that code assign "data" object to the JMeter variable like this
vars.put("A1", data.getAbsolutePath());
Taken reference from How to Extract Data From Files With JMeter This might helps you.