Resin 폴더에 있는 샘플 파일을 컴파일 하는데요 ;;
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import java.io.*;
import java.util.*;

import javax.servlet.http.*;
import javax.servlet.*;

public class HelloServlet extends HttpServlet {
  public void doGet (
HttpServletRequest req,
HttpServletResponse res
    ) throws ServletException, IOException
  {
    res.setContentType(\"text/html\");
    PrintWriter pw = res.getWriter();

    pw.println(\"\");
    pw.println();
    pw.println(\"\");
    pw.println(\"\");
    pw.println();
    pw.println(\"\");
    pw.println();
    pw.println(\"\");
    pw.println(\"\");
    pw.println();
    pw.println(\"\");
    pw.println();
    pw.println(\"

Hello, world!

\");
    pw.println();

    ServletContext app = getServletContext();
    
    pw.println(\"The source of this servlet is in: 

\");
    pw.println(app.getRealPath(\"WEB-INF/classes/HelloServlet.java\"));
    pw.println(\"

 and the compiled class is in:
\");
    pw.println(app.getRealPath(\"WEB-INF/classes/HelloServlet.class\"));
    pw.println(\"\");
    pw.close();
  }

  public HelloServlet() {}
}
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HelloServlet.java:29: package javax.servlet.http does not exist
import javax.servlet.http.*;
HelloServlet.java:30: package javax.servlet does not exist
import javax.servlet.*;
...
총 8개의 오류가 나네요...
javax.servelet 패키지가 class path로 잡히지 않은 것 같은데요 ;;
resin/lib 폴더에 있는 resin.jar 파일을 class path로 잡았는데... 그것 외에 다른것을 또 잡아야 하나요 ?

오늘 2번째 질문이네요...
암튼 부탁드립니다. ^^

해당 라이브러리를 찾지 못해서 나타나는 현상입니다. 

$RESIN_HOME/lib에 서블릿 엔진을 위한 라이브러리들이 있습니다. 

직접 컴파일 해서 사용하신다면 거기에 있는 라이브러리들을 클래스패스 환경에 잡으시면 됩니다.

javax.servlet.http.*, javax.servlet.* 패키지는 jsdk23.jar에 있습니다.