Reviews : Converting XML to JavaBeans with XMLBeans :

The First Try

For our first example we'll use an XML Schema file I'd used earlier in an article about Castor. Here a simplified deployment descriptor for a web application was used as an example. Let's look at a picture of this schema:

Figure 1. The structure of the web.xml schema (webapp.xsd)
 

To open a new window with a listing of the schema file click here.

Here's an example of a deployment descriptor file using this schema, namely the one used by Struts' "blank application":

Listing 1. web.xml for the Struts-blank application

<?xml version="1.0" encoding="ISO-8859-1"?>

<!DOCTYPE web-app
  PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.2//EN"
  "http://java.sun.com/j2ee/dtds/web-app_2_2.dtd">

<web-app>

  <!-- Standard Action Servlet Configuration (with debugging) -->
  <servlet>
    <servlet-name>action</servlet-name>
    <servlet-class>org.apache.struts.action.ActionServlet</servlet-class>
    <init-param>
      <param-name>config</param-name>
      <param-value>/WEB-INF/struts-config.xml</param-value>
    </init-param>
    <init-param>
      <param-name>debug</param-name>
      <param-value>2</param-value>
    </init-param>
    <init-param>
      <param-name>detail</param-name>
      <param-value>2</param-value>
    </init-param>
    <load-on-startup>2</load-on-startup>
  </servlet>

  <!-- Standard Action Servlet Mapping -->
  <servlet-mapping>
    <servlet-name>action</servlet-name>
    <url-pattern>*.do</url-pattern>
  </servlet-mapping>

  <!-- The Usual Welcome File List -->
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>

  <!-- Struts Tag Library Descriptors -->
  <taglib>
    <taglib-uri>/tags/struts-bean</taglib-uri>
    <taglib-location>/WEB-INF/struts-bean.tld</taglib-location>
  </taglib>

  . . . (several other taglibs follow) . . .
</web-app>

Our first program will read and parse this file using XMLBeans. The first step is to generate the specific XMLBeans classes from the schema.

Go to the directory where your webapp.xsd file is located and enter:

    scomp -out webapp.jar webapp.xsd

The -out parameter is used to name the output jar file. This is the result you should see:

[There's a known bug in scomp. If you receive a "CreateProcess exception", then the scomp utility is trying to find the Java compiler (the javac.exe file) in the Java runtime directory, instead of looking in the JDK bin directory. The fix is to set the location of the JDK bin-directory in the start of the PATH environment variable. You may find more information in the newsgroup(see the resources section).

Look into the generated webapp.jar file to see what was generated. You'll notice that the original schema file is there and several files that contains the element names from the xsd: WebApp, ServletMapping, Taglib etc. There are many files, and all in all it's a somewhat confusing picture.

If you want to see the Java code that was generated there is a "-src" option that saves the source to a specified directory.

How to Add Java Applets to Your Site

New on the Java Boutique:

New Review:

Time Management Made Easy with the Quartz Enterprise Job Scheduler
Why not just use the Java timer API? This open source scheduling API boasts simplicity, ease-of-integration, a well-rounded feature set, and it's free!

New Applet:

Reverse Complement
Reverse Complement is a simple applet that converts DNA or RNA sequences into three useful formats.

Elsewhere on internet.com:

WebDeveloper Java
Lots of Java information on webdeveloper.com

WDVL Java
Thorough Java resource at the Web Developer's Virtual Library.

ScriptSearch Java
Hundreds of free Java code files to download.

jGuru: Your View of the Java Universe
Customizable portal with online training, FAQs, regular news updates, and tutorials.