Calling java object/class from java servlet

Question

I have created a dynamic web project in eclipse.

It contains a Servlet ResidentApi.java and two java classes:GeoLocationDemo.java and Geolocation.java. I am calling GeoLocationDemo.java from my servlet and getting result in a ResultSet.But i am not getting any value in ResultSet.

When i ran same GeoLocationDemo.java separatly i am getting right results.I don't know servlet is able to call my java class or not but if it is then why i am not getting results.

I am having hard time debugging it.What i am doing is running .war file of this project every time on tomcat server and checking results there.Please suggest a good method to test it on eclipse.

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    // TODO Auto-generated method stub


    response.setContentType("text/html"); 
    PrintWriter out = response.getWriter();

    ResultSet rs = null;
    try{    
        GeoLocationDemo geo = new GeoLocationDemo();   //Here i created a new object
         rs = geo.getResults();                       //here i called a method of GeoLocation
    }catch(Exception e){
        // System.out.println(e);
     out.write("<head><b You suck</b></head>");
    }

    out.write("<head><b>Congratulation! connected</b></head>");    //i am getting this output
     try{     
         while(rs.next()){
         String s = rs.getString("Details");
         out.write("<head><b> "+s+ " </b></head>");           //not able to get this output
     }

        }catch(Exception e){
                // System.out.println(e);
                 out.write("<head><b>You Built </b></head>");
             }

         out.close();


}

i am uploading .war file on tomcat server and their i am getting only above specified output.i don't know how to run servlet in eclipse. — Ajay Singh, Dec 28 '14 at 19:12
Your tagging is incorrect, maybe browser doesn't show that. To be sure about this problem, right click in your browser and select `View Page Source`. Can you see your data there? — Ali Sepehri.Kh, Dec 28 '14 at 19:16
no data there also.Is it allowed to call classes in Servlets? — Ajay Singh, Dec 28 '14 at 19:20
Yes, sure. Does catch section execute? Do you see `You Built`? — Ali Sepehri.Kh, Dec 28 '14 at 19:23
Ok, you are getting an exception, There is a problem about using ResultSet. — Ali Sepehri.Kh, Dec 28 '14 at 19:28
ok,i want to ask one thing, i have cleared first try catch block without getting any exception.Does this mean that i am getting right results in ResultSet? — Ajay Singh, Dec 28 '14 at 19:32
If you can see your data, that means you're getting right results. What do you mean? Do you have any column that named `"Details"`? Are you sure? — Ali Sepehri.Kh, Dec 28 '14 at 19:36
i have 12 columns and one is Details for sure.Can any how my program skip first try catch block even if their is some mistake in geo.getResults() ? — Ajay Singh, Dec 28 '14 at 19:42
You're doing it now, You swallow the exception and continue the program (is not recommended). Comment the body of while and run it again. Can you see `You Built` in output yet? — Ali Sepehri.Kh, Dec 28 '14 at 19:47
Ok done, i was not handling exceptions correctly.Thanks a lot! — Ajay Singh, Dec 28 '14 at 20:10

score 0 · Accepted Answer · answered Dec 28 '14 at 19:40

Don't put everything in a <head> tag! Open a body somewhere. Don't silently swallow any Exception you might be getting. Do remember to close() the ResultSet. Also, you should probably be returning all of your data in a List with a POJO.

out.write("<body>");
out.write("<b>Congratulation! connected</b><br/>");
try {
    while (rs.next()) {
        String s = rs.getString("Details");
        out.write("<b> "+s+ "</b><br/>");
    }
} catch (Exception e){
    // System.out.println(e);
    out.write("<b>" + e.getMessage() + "</b>");
    e.printStackTrace(out);
} finally {
    try { 
        out.close(); 
    } catch (Exception ignored) {
    }
    try {
        rs.close();
    } catch (Exception ignored) {
    }
}

score 0 · Answer 2 · edited May 23 '17 at 11:49

0

configure remote debugging between your IDE and Tomcat server e.g. take a look on Remote debugging Tomcat with Eclipse
localize the problem - is the problem in GeoLocationDemo or in ResultSet or in output processing

p.s. do not close resources you never open - out.close(); - it is managed by servlet container

edited May 23 '17 at 11:49

Community

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answered Dec 28 '14 at 19:41

ursa

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Thanks,Remote Debugging will surely help. – Ajay Singh Dec 28 '14 at 19:48

Calling java object/class from java servlet

2 Answers2