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From Matt Larson <lars...@ncep.noaa.gov>
Subject [Fwd: Tomcat's non-polymorphic request handler.]
Date Wed, 26 Sep 2001 19:25:19 GMT
I sent this to the tomcat user group, but got no response.

Comments?

I'm having some difficulty with the polymorphic behavior of Tomcat's
request handler.
Consider the following:

package RMS;
import java.lang.Integer;

public class TestPolyMorph {
    int i;
    String s;
    public void setNumberVar(String i) {
        this.i = Integer.parseInt(i);
    }
    public void setNumberVar(int i) {
        this.i = i;
    }
    public int getNumber() {
        return(i);
    }
    public void setStringVar(String s) {
        this.s = s;
    }
    public String getStringVar(String s) {
        return(s);
    }
    public TestPolyMorph() {
    }
}

... and the .JSP file:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
        "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<!--  <meta http-equiv="Pragma" content="no-cache">
  <meta http-equiv="Expires" content="Mon, 01 Jan 1990 00:00:01 GMT">
-->
  <meta http-equiv="Content-Type"
content="text/html;CHARSET=iso-8859-1">
  <meta http-equiv="Content-Style-Type" content="text/css">
</head>
<%@ page language="java" import="RMS.*" %>
<jsp:useBean    id="ui" class="RMS.TestPolyMorph" scope="session"/>
<jsp:setProperty name="ui" property="*"/>
<body>
Testing... Testing... Testing.
</body>
</html>


Now... the passing a non-integer value for the property: numberVar will
yield a stack trace:
http://SERVER:PORT/CONTEXT/jsp/TestPolyMorph.jsp?numberVar=foobar

org.apache.jasper.JasperException: foobar
 at
org.apache.jasper.runtime.JspRuntimeLibrary.introspecthelper(JspRuntimeLibrary.java:204)

 at
org.apache.jasper.runtime.JspRuntimeLibrary.introspect(JspRuntimeLibrary.java:152)

 at

jsp._0002fjsp_0002fTestPolyMorph_0002ejspTestPolyMorph_jsp_2._jspService(_0002fjsp_0002fTestPolyMorph_0002ejspTestPolyMorph_jsp_2.java:91)

 at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:119)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
 at
org.apache.jasper.servlet.JspServlet$JspServletWrapper.service(JspServlet.java:177)

 at
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:318)

 at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:391)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
 at
org.apache.tomcat.core.ServletWrapper.doService(ServletWrapper.java:404)

 at org.apache.tomcat.core.Handler.service(Handler.java:286)
 at
org.apache.tomcat.core.ServletWrapper.service(ServletWrapper.java:372)
 at
org.apache.tomcat.core.ContextManager.internalService(ContextManager.java:797)

 at
org.apache.tomcat.core.ContextManager.service(ContextManager.java:743)
 at
org.apache.tomcat.service.http.HttpConnectionHandler.processConnection(HttpConnectionHandler.java:210)

 at
org.apache.tomcat.service.TcpWorkerThread.runIt(PoolTcpEndpoint.java:416)

 at
org.apache.tomcat.util.ThreadPool$ControlRunnable.run(ThreadPool.java:498)

 at java.lang.Thread.run(Thread.java:484)

Root cause:
org.apache.jasper.JasperException: 3.2
 at
org.apache.jasper.runtime.JspRuntimeLibrary.convert(JspRuntimeLibrary.java:138)

 at
org.apache.jasper.runtime.JspRuntimeLibrary.introspecthelper(JspRuntimeLibrary.java:198)

 at
org.apache.jasper.runtime.JspRuntimeLibrary.introspect(JspRuntimeLibrary.java:152)

 at

jsp._0002fjsp_0002fTestPolyMorph_0002ejspTestPolyMorph_jsp_2._jspService(_0002fjsp_0002fTestPolyMorph_0002ejspTestPolyMorph_jsp_2.java:91)

 at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:119)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
 at
org.apache.jasper.servlet.JspServlet$JspServletWrapper.service(JspServlet.java:177)

 at
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:318)

 at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:391)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
 at
org.apache.tomcat.core.ServletWrapper.doService(ServletWrapper.java:404)

 at org.apache.tomcat.core.Handler.service(Handler.java:286)
 at
org.apache.tomcat.core.ServletWrapper.service(ServletWrapper.java:372)
 at
org.apache.tomcat.core.ContextManager.internalService(ContextManager.java:797)

 at
org.apache.tomcat.core.ContextManager.service(ContextManager.java:743)
 at
org.apache.tomcat.service.http.HttpConnectionHandler.processConnection(HttpConnectionHandler.java:210)

 at
org.apache.tomcat.service.TcpWorkerThread.runIt(PoolTcpEndpoint.java:416)

 at
org.apache.tomcat.util.ThreadPool$ControlRunnable.run(ThreadPool.java:498)

 at java.lang.Thread.run(Thread.java:484)


Even though there is indeed a method signature:
setNumberVar(String i);
....
Tomcat prefers to use (through introspection):
setNumberVar(int i);

The beans I use to handle property settings must continue to use
polymorphism.

Any ideas?

Thanks,

matt


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