Example Java Class Converted from a JSP Page

JSP Tutorials - Herong's Tutorial Examples

∟Example Java Class Converted from a JSP Page

This section provides a tutorial example Java class converted by Tomcat from the JSP page, Hello_Scripting.jsp. Scripting elements included in the JSP page are converted correctly.

What is the location of those Servlet class files converted from my JSP pages by the Tomcat server? The answer is depending on the Tomcat version and configuration settings.

If you are using Tomcat with default settings, JSP pages deployed to the default application folder, .\webapps\ROOT, will be converted to Servlet class files in the default work folder, .\work\Catalina\localhost\_\org\apache\jsp. If you are using other versions of Tomcat, the Servlet class file location could be different.

Here is where I found the converted Servlet class file of my Hello-Scripting.jsp used in the previous tutorial:

JSP page location:
\local\tomcat\webapps\ROOT\Hello-Scripting.jsp

Converted Java source code location:
\local\tomcat\work\Catalina\localhost\_\org\apache\jsp
   \Hello_005fScripting_jsp.java

Compiled Java bytecode location:
\local\tomcat\work\Catalina\localhost\_\org\apache\jsp
   \Hello_005fScripting_jsp.class

Notice that:

For the default application, Tomcat uses "_" as the folder name for Java classes, which is different than folder name for JSP pages, "ROOT".
When converting the JSP page to a Java class, Tomcat automatically put the class in the org.apache.jsp class package.
When naming the converted Java class, Tomcat uses the JSP page file name with "_jsp" added to the end.
When special characters are used in the JSP page file name, Tomcat replaces them with their UTF-16 values prefixed with "_". For example, "_" will be replaced with "_005f".

Now let's see how the converted Java class looks like. Open Hello_005fScripting_jsp.java:

/*
 * Generated by the Jasper component of Apache Tomcat
 * Version: Apache Tomcat/9.0.12
 * ...
 */
package org.apache.jsp;

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

public final class Hello_005fScripting_jsp
    extends org.apache.jasper.runtime.HttpJspBase
    implements org.apache.jasper.runtime.JspSourceDependent {

   private String greeting() {
      return "Scripting Elements:";
   }

  private static final javax.servlet.jsp.JspFactory _jspxFactory =
          javax.servlet.jsp.JspFactory.getDefaultFactory();

  private static java.util.Map<java.lang.String,java.lang.Long>
          _jspx_dependants;

  private javax.el.ExpressionFactory _el_expressionfactory;
  private org.apache.tomcat.InstanceManager _jsp_instancemanager;

  public java.util.Map<java.lang.String,java.lang.Long>
          getDependants() {
    return _jspx_dependants;
  }

  public void _jspInit() {
    _el_expressionfactory =
          _jspxFactory.getJspApplicationContext(
          getServletConfig().getServletContext()
          ).getExpressionFactory();
    _jsp_instancemanager =
org.apache.jasper.runtime.InstanceManagerFactory.getInstanceManager(
          getServletConfig());
  }

  public void _jspDestroy() {
  }

  public void _jspService(
        final javax.servlet.http.HttpServletRequest request,
        final javax.servlet.http.HttpServletResponse response)
        throws java.io.IOException, javax.servlet.ServletException {

    final javax.servlet.jsp.PageContext pageContext;
    javax.servlet.http.HttpSession session = null;
    final javax.servlet.ServletContext application;
    final javax.servlet.ServletConfig config;
    javax.servlet.jsp.JspWriter out = null;
    final java.lang.Object page = this;
    javax.servlet.jsp.JspWriter _jspx_out = null;
    javax.servlet.jsp.PageContext _jspx_page_context = null;


    try {
      response.setContentType("text/html");
      pageContext = _jspxFactory.getPageContext(
          this, request, response, null, true, 8192, true);
      _jspx_page_context = pageContext;
      application = pageContext.getServletContext();
      config = pageContext.getServletConfig();
      session = pageContext.getSession();
      out = pageContext.getOut();
      _jspx_out = out;

      out.write("<html><body>\r\n");
      out.write("<!-- Hello_Scripting.jsp\r\n");
      out.write(
"   Copyright (c) 2002 HerongYang.com. All Rights Reserved.\r\n");
      out.write("-->\r\n");
      out.write("<pre>\r\n");
      out.print( greeting() );
      out.write('\r');
      out.write('\n');
 out.println("Hello world!");
      out.write('\r');
      out.write('\n');
      out.print( "-- From JSP" );
      out.write("\r\n");
      out.write("</pre>\r\n");
      out.write("</body></html>\r\n");
    } catch (java.lang.Throwable t) {
      if (!(t instanceof javax.servlet.jsp.SkipPageException)){
        out = _jspx_out;
        if (out != null && out.getBufferSize() != 0)
          try { out.clearBuffer(); } catch (java.io.IOException e) {}
        if (_jspx_page_context != null)
          _jspx_page_context.handlePageException(t);
        else throw new ServletException(t);
      }
    } finally {
      _jspxFactory.releasePageContext(_jspx_page_context);
    }
  }
}