Question

I need to know if there are any issues with the below code as far as threading goes. I was always under the impression that so long as class level variables are not used threading is not an issue.

public class UploadReferralImage extends HttpServlet
{
    String CLASS_NAME = "UploadReferralImage";

public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
{
   // Not handling Get, service must be invoked via Post.
}

public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
{
    String METHOD_NAME = "doPost";
    LogHelper.debug(PACKAGE_NAME, CLASS_NAME, METHOD_NAME, "Made it to the servlet");
    String reply = upload(request);
    response.setHeader("Content-Type", "text/xml");
    response.getWriter().write(reply);
    response.getWriter().flush();
    response.getWriter().close();
}

public String upload(HttpServletRequest request)
{

    String METHOD_NAME = "upload";
    LogHelper.debug(PACKAGE_NAME, CLASS_NAME, METHOD_NAME, "Inside upload");
    String replyMsg = "Unable to call ImageUpload";

    try
    {
        ObjectInputStream inputFromApplet = new ObjectInputStream(request.getInputStream());
        FileBean fBean = (FileBean) inputFromApplet.readObject();

        inputFromApplet.close();
        LogHelper.debug(PACKAGE_NAME, CLASS_NAME, METHOD_NAME, fBean.getFileName());

        replyMsg = doImageUpload(fBean);

        } 
        catch (IOException e)
    {   
        e.printStackTrace();
            replyMsg = "Exception :" + e.toString();

    } 
        catch (ClassNotFoundException e)
    {
        e.printStackTrace();
            replyMsg = "Exception :" + e.toString();
    }

    return replyMsg;
}

private String doImageUpload(FileBean fBean)
{
       //Save the file and return the response
       SaveCaseClientAgent saveCaseClientAgent = new SaveCaseClientAgent();
       saveCaseClientAgent.save(fBean);
}

Answer 1

You are correct.

As long as you stay away from using class-level variables your Servlet will be thread safe.

To be safe, might as well make your class-level String final:

final String CLASS_NAME = "UploadReferralImage";