how to write header and records in csv file as response using java

I am trying to download a csv file with the customized header and records in it. But i am not able to set header and fill the data in the csv file, but it does append the source code of the same view page. I want the csv file as following ouput.

empId EmpName Designation

101 John Programmer

102 Tom Manager

I am using the following code, it does not contain the code to write in the file. How can i achieve the expected output?

  try {
        response.reset();            
        response.setContentType(mimeType);
        String headerKey = "Content-Disposition";
        String fileName =  "downloadEmployee.csv";
        String headerValue = String.format("attachment; filename=\"%s\"", fileName);
        response.setHeader(headerKey, headerValue);
                    
    } catch (Exception e) {
        e.printStackTrace();
    }