Oracle JavaServer Pages Developer's Guide and Reference
Release 8.1.7
Part Number A83726-01

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Functionality of the OracleJSP Translator

JSP translators generate standard Java code for a JSP page implementation class. This class is essentially a servlet class wrapped with features for JSP functionality.

This section discusses general functionality of the OracleJSP translator, focusing on its behavior in on-demand translation environments, such as Apache/JServ or the Oracle Internet Application Server. The following topics are covered:

You must pre-translate JSP pages targeted for the Oracle Servlet Engine, either as a result of running the session shell publishjsp command (for deployment with server-side translation) or by running the ojspc pre-translation tool directly (for deployment with client-side translation). In either case, there are some differences in functionality compared with the discussion in this section, such as in placement of output files. See "Translating and Publishing JSP Pages in Oracle8i (Session Shell publishjsp)" and "The ojspc Pre-Translation Tool" for information.

Generated Code Features

This section discusses general features of the page implementation class code that is produced by the OracleJSP translator in translating JSP source (.jsp and .sqljsp files).

Features of Page Implementation Class Code

When the OracleJSP translator generates servlet code in the page implementation class, it automatically handles some of the standard programming overhead. For both the on-demand translation model and the pre-translation model, generated code automatically includes the following features:

For introductory information about key JSP and servlet classes and interfaces, see Appendix B, "Servlet and JSP Technical Background".

Inner Class for Static Text

The service method, _jspService(), of the page implementation class includes print commands--out.print() calls on the implicit out object--to print any static text in the JSP page. The OracleJSP translator, however, places the static text itself in an inner class within the page implementation class. The service method out.print() statements reference attributes of the inner class to print the text.

This inner class implementation results in an additional .class file when the page is translated and compiled. In a client-side pre-translation scenario (usually for deployment to Oracle8i), be aware this means there is an extra .class file to deploy.

The name of the inner class will always be based on the base name of the .jsp file or .sqljsp file. For mypage.jsp, for example, the inner class (and its .class file) will always include "mypage" in its name.

Note:

The OracleJSP translator can optionally place the static text in a Java resource file, which is advantageous for pages with large amounts of static text. (See "Workarounds for Large Static Content in JSP Pages".) You can request this feature through the OracleJSP external_resource configuration parameter (for on-demand translation) or the ojspc -extres option (for pre-translation). Enabling hotloading (for deployment to Oracle8i) also results in the static text going into a resource file.

Even when static text is placed in a resource file, the inner class is still produced, and its .class file must be deployed. (This is only noteworthy if you are in a client-side pre-translation scenario.)  

Generated Package and Class Names (On-Demand Translation)

Although the Sun Microsystems JavaServer Pages Specification, Version 1.1 defines a uniform process for parsing and translating JSP text, it does not describe how the generated classes should be named--that is up to each JSP implementation.

This section describes how OracleJSP creates package and class names when it generates code during translation.

Important:

In OracleJSP release 8.1.7 (1.1.0.0.0), the URL path directory and .jsp file name (which are used in generating package and class names) are restricted to valid Java package and class identifiers. For example, a path directory or .jsp name cannot begin with a number. It is also invalid to use Java reserved words, such as for or class, as a path directory or .jsp name (such as class.jsp). Such implementation details may change in future releases.  

Package Naming

In an on-demand translation scenario, the URL path that is specified when the user requests a JSP page--specifically, the path relative to the doc root or application root--determines the package name for the generated page implementation class. Each directory in the URL path represents a level of the package hierarchy.

It is important to note, however, that generated package names are always lowercase, regardless of the case in the URL.

Consider the following URL as an example: 

http://host[:port]/HR/expenses/login.jsp

In OracleJSP release 8.1.7 (1.1.0.0.0), this results in the following package specification in the generated code (implementation details are subject to change in future releases): 

package hr.expenses;

No package name is generated if the JSP page is at the doc root or application root directory, where the URL is as follows: 

http://host[:port]/login.jsp

Class Naming

The base name of the .jsp file (or .sqljsp file) determines the class name in the generated code.

Consider the following URL example: 

http://host[:port]/HR/expenses/UserLogin.jsp

In OracleJSP release 8.1.7 (1.1.0.0.0), this yields the following class name in the generated code (implementation details are subject to change in future releases): 

public class UserLogin extends ...

Be aware that the case (lowercase/uppercase) that end-users type in the URL must match the case of the actual .jsp or .sqljsp file name. For example, they can specify UserLogin.jsp if that is the actual file name, or userlogin.jsp if that is the actual file name, but not userlogin.jsp if UserLogin.jsp is the actual file name.

In OracleJSP release 8.1.7 (1.1.0.0.0), the translator determines the case of the class name according to the case of the file name. For example:

If you care about the case of the class name, then you must name the .jsp file or .sqljsp file accordingly. However, because the page implementation class is invisible to the end-user, this is usually not a concern.

Generated Files and Locations (On-Demand Translation)

This section describes files that are generated by the OracleJSP translator and where they are placed. For pre-translation scenarios, ojspc places files differently and has its own set of relevant options--see "Summary of ojspc Output Files, Locations, and Related Options".

The following subsections mention several OracleJSP configuration parameters. For more information about them, see "OracleJSP Configuration Parameters (Non-OSE)" and "OracleJSP Configuration Parameter Settings".

Files Generated by OracleJSP

This section considers both regular JSP pages (.jsp files) and SQLJ JSP pages (.sqljsp files) in listing files that are generated by the OracleJSP translator. For the file name examples, presume a file Foo.jsp or Foo.sqljsp is being translated.

Source files:

Binary files:

OracleJSP Translator Output File Locations

OracleJSP uses the Web server document repository to generate or load translated JSP pages.

By default, the root directory is the Web server doc root directory (for Apache/JServ) or the servlet context root directory of the application the page belongs to.

You can specify an alternative root directory through the OracleJSP page_repository_root configuration parameter.

In OracleJSP release 8.1.7 (1.1.0.0.0), generated files are placed as follows (implementation details may change in future releases):

Sample Page Implementation Class Source

This section uses an example to illustrate the information in the preceding sections.

Consider the following scenario:

Sample Page Source: hello.jsp

Following is the JSP code in hello.jsp: 

<HTML>
<HEAD><TITLE>The Hello User JSP</TITLE></HEAD>
<BODY>
<% String user=request.getParameter("user"); %>
<H3>Welcome <%= (user==null) ? "" : user %>!</H3>
<P><B> Today is <%= new java.util.Date() %>. Have a nice day! :-)</B></P>
<B>Enter name:</B>
<FORM METHOD=get>
<INPUT TYPE="text" NAME="user" SIZE=15>
<INPUT TYPE="submit" VALUE="Submit name">
</FORM>
</BODY>
</HTML>

Sample: Generated Package and Class

Because hello.jsp is in the test subdirectory of the root directory (htdocs), OracleJSP release 8.1.7 (1.1.0.0.0) generates the following package name in the page implementation code: 

package test;

The Java class name is identical to the base name of the .jsp file (case included), so the following class definition is generated in the page implementation code: 

public class hello extends oracle.jsp.runtime.HttpJsp
{
   ...
}

(Because the page implementation class is invisible to the end-user, the fact that its name does not adhere to Java capitalization conventions is generally not a concern.)

Sample: Generated Files

Because hello.jsp is located as follows: 

htdocs/test/hello.jsp

OracleJSP release 8.1.7 (1.1.0.0.0) generates output files as follows (the page implementation class .java file and .class file, and the inner class .class file, respectively): 

htdocs/_pages/test/hello.java
htdocs/_pages/test/hello.class
htdocs/_pages/test/hello$__jsp_StaticText.class

Note:

These file names are based specifically on the OracleJSP 1.1.0.0.0 implementation; the exact details may change in future releases. All file names will always include the base "hello", however.  

Sample Page Implementation Code: hello.java

Following is the generated page implementation class Java code (hello.java), as generated by OracleJSP release 8.1.7 (1.1.0.0.0): 

package test;

import oracle.jsp.runtime.*;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.jsp.*;
import java.io.*;
import java.util.*;
import java.lang.reflect.*;
import java.beans.*;


public class hello extends oracle.jsp.runtime.HttpJsp {

  public final String _globalsClassName = null;

  // ** Begin Declarations


  // ** End Declarations

  public void _jspService(HttpServletRequest request, HttpServletResponse 
response) throws IOException, ServletException {

    /* set up the intrinsic variables using the pageContext goober:
    ** session = HttpSession
    ** application = ServletContext
    ** out = JspWriter
    ** page = this
    ** config = ServletConfig
    ** all session/app beans declared in globals.jsa
    */
    JspFactory factory = JspFactory.getDefaultFactory();
    PageContext pageContext = factory.getPageContext( this, request, response, 
null, true, JspWriter.DEFAULT_BUFFER, true);
    // Note: this is not emitted if the session directive == false
    HttpSession session = pageContext.getSession();
    if (pageContext.getAttribute(OracleJspRuntime.JSP_REQUEST_REDIRECTED, 
PageContext.REQUEST_SCOPE) != null) {
      pageContext.setAttribute(OracleJspRuntime.JSP_PAGE_DONTNOTIFY, "true", 
PageContext.PAGE_SCOPE);
      factory.releasePageContext(pageContext);
      return;
}
    ServletContext application = pageContext.getServletContext();
    JspWriter out = pageContext.getOut();
    hello page = this;
    ServletConfig config = pageContext.getServletConfig();

    try {
      // global beans
      // end global beans


      out.print(__jsp_StaticText.text[0]);
      String user=request.getParameter("user"); 
      out.print(__jsp_StaticText.text[1]);
      out.print(  (user==null) ? "" : user );
      out.print(__jsp_StaticText.text[2]);
      out.print(  new java.util.Date() );
      out.print(__jsp_StaticText.text[3]);

      out.flush();

    }
    catch( Exception e) {
      try {
        if (out != null) out.clear();
      }
      catch( Exception clearException) {
      }
      pageContext.handlePageException( e);
    }
    finally {
      if (out != null) out.close();
      factory.releasePageContext(pageContext);
    }

  }
  private static class __jsp_StaticText {
    private static final char text[][]=new char[4][];
    static {
      text[0] = 
      "<HTML>\r\n<HEAD><TITLE>The Welcome User 
JSP</TITLE></HEAD>\r\n<BODY>\r\n".toCharArray();
      text[1] = 
      "\r\n<H3>Welcome ".toCharArray();
      text[2] = 
      "!</H3>\r\n<P><B> Today is ".toCharArray();
      text[3] = 
      ". Have a nice day! :-)</B></P>\r\n<B>Enter name:</B>\r\n<FORM 
METHOD=get>\r\n<INPUT TYPE=\"text\" NAME=\"user\" SIZE=15>\r\n<INPUT 
TYPE=\"submit\" VALUE=\"Submit 
name\">\r\n</FORM>\r\n</BODY>\r\n</HTML>".toCharArray();
    }
  }
}

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