HelloWorld Servlet
Sample
This document contains the following topics
:
Overview
of HelloWorld Servlet Sample
This Sample describes how
to create a basic servlet application.The Servlet application creates
a simple HTML page and displays "Hello Oracle World" string in it.
Steps in the Sample
| Step 1. |
After invoking the application, it will display a simple HTML pagedisplaying
the "Hello Oracle World" String. |
Required Software
- Oracle9iAS
Containers for J2EE (OC4J) downloadable from OTN
.
- JDK Version 1.2 or higher.
- Oracle9i
JDeveloper downloadable from OTN
.
Install the above required software and
continue with the following instructions on the system where OC4J
is installed.
Pre-Requisite
Setup
| OC4J(Oracle9iAS
Container for J2EE) Setup |
Refer the OC4J documentation
for basic installation, testing the default configurations, starting
and stopping OC4J server. Also refer the section for Servlets in
particular. This should basically give general instructions to deploy
and run the web applications. |
| CLASSPATH |
Add oc4j.jar, its present under
<J2EE_HOME>. Add servlet.jar
which is present at <J2EE_HOME>\lib |
| JAVA_HOME |
Set the JAVA_HOME system variable
where JDK is installed (Example: d:\jdk1.2.1 ) |
Note: If <OC4J_HOME> is where
your OC4J Home is installed, <J2EE_HOME> is <OC4J_HOME>\j2ee\home
. For example: If oc4j is installed at d:\oc4j then d:\oc4j\j2ee\home
will be refered as <J2EE_HOME>
Description
of Files in the Sample
The sample is provided as a jar file
HelloWorld.jar which contains the following files required for the
sample :
| File Name |
Description |
| HelloWorld.java |
The source file which displays the
message "Hello Oracle World!" |
| web.xml |
This file is used to define the
Web application deployment parameters and is included in the WAR(Web
Archive) file. Only required for WAR deployment. |
| Readme.html |
This file. |
Installing
and Preparing the Sample
Note: Linux Users should use /
instead of \ in the path variables.
Simple
Deployment:
| Step 1. |
Extract the HelloWorld.jar
file using
jar xvf HelloWorld.jar
After extracting the .jar file, it
creates 'HelloWorld' directory and all required files in it. |
| Step 2. |
Under the HelloWorld directory created
in Step 1, compile the *.java file to create the class file by using
the command below:
javac *.java
This will create HelloWorld.class |
| Step 3. |
Move
HelloWorld.class file to <J2EE_HOME>\default-web-app\Web-inf\classes
directory. |
| Step 4. |
Now start OC4J by giving the command
from the
<J2EE_HOME>
directory.
java -jar oc4j.jar |
Now the sample is ready to be
run .
WAR
Deployment to OC4J using Standard J2EE way:
| Step 1. |
Extract
the HelloWorld.jar file using following command:
jar xvf HelloWorld.jar
After extracting the .jar file, it
creates 'HelloWorld' directory and all required files of the sample
in it. |
| Step 2. |
Under the HelloWorld directory created
in Step 1, compile the *.java files to create the class files by
using the command below:
javac *.java
This will create HelloWorld.class |
| Step 3. |
Create
the following directories say, in d:\.
d:\HelloWorld
d:\HelloWorld\src
d:\HelloWorld\WEB-INF
d:\HelloWorld\WEB-INF\classes |
| Step 4. |
Move Readme.html
file to d:\HelloWorld\ directory. |
| Step 5. |
Move web.xml
file to d:\HelloWorld\WEB-INF. |
| Step 6. |
Move the
HelloWorld.java to d:\HelloWorld\src |
| Step 7. |
Move the HelloWorld.class to d:\HelloWorld\WEB-INF\classes |
| Step 8. |
Create the war file, HelloWorld.war
cd d:\HelloWorld
jar -cvfM HelloWorld.war . |
| Step 9. |
Copy the file HelloWorld.war
to <J2EE_HOME>\applications. |
| Step 10. |
Open the
file application.xml present in <J2EE_HOME>\config
directory and after
<web-module id="defaultWebApp"
path="../default-web-app" /> line add:
<web-module id="HelloWorld"
path="../applications/HelloWorld.war" /> |
| Step 11. |
Open the
http-web-site.xml file
present in <J2EE_HOME>\config directory and
after <default-web-app application="default"
name="defaultWebApp" /> line add:
<web-app application="default"
name="HelloWorld" root="/technology/HelloWorld" /> |
| Step 12. |
Now start
OC4J by giving the command from the
<J2EE_HOME> directory.
java -jar oc4j.jar |
Now the sample is ready to be run
.
Deploying
the servlet to OC4J using Oracle9i
JDeveloper (automated creation and deployment of .war file)
Following are the steps that are to be followed to deploy and run the
servlet from Oracle9i
JDeveloper
| Step 1. |
Extract the HelloWorld.jar
file.
jar xvf HelloWorld.jar
After extracting the .jar file,
it creates 'HelloWorld' directory and all required files of the
sample in it. |
| Step 2. |
Click File -> New -> Projects
-> Workspace. Name the workspace as HelloWorld.jws and create
it in the directory <Base>\HelloWorld directory, where
<Base> is the directory where you have extracted the sample.
'Create Empty Project'
checkbox is checked by default, this
start project creation wizard. |
| Step 3. |
Let the Project directory
be <Base>\Helloworld directory and the name of the project
be HelloWorld.jpr. Right click on HelloWorld.jpr and select
Project Settings -> Development -> Libraries and include the
following libraries in the "Available" list. (JDeveloper Runtime,
Servlet Runtime). Also right click on HelloWorld.jpr and select
Project Settings - > Common - >
Input paths ->Java Source Path and make sure that it points to
the directory where you have extracted this sample. |
| Step 4. |
Create an Application
Server Connection by clicking on the Connections Node. Right click
on Application Servers and select "New Connection". Provide
the appropriate connection parameters of the Application Server
to which you want to deploy the servlets. |
| Step 5. |
Select HelloWorld.jpr
and Click on "+" button. Now add the source file HelloWorld.java
to HelloWorld.jpr. It is in <Base>\HelloWorld directory. |
| Step 6. |
Make the project by
right clicking on the Helloworld.jpr and selecting the make
option from it. |
| Step 7. |
Select File ->
New -> Deployment Profiles -> J2EE Web Module (WAR File),
save the Deployment Profile, this brings a File Dialog, where you
can mention the name of the deployment profile and the directory
to which you want to save the profile. Accept the default values
for the directory and mention the file name as HelloWorld.deploy
Click Save. Save the WAR file and EAR file in <Base>\HelloWorld
directory with the name HelloWorld.war and HelloWorld.ear.
Click OK (Here <Base> directory is the directory where you
have extracted the sample) |
| Step 8. |
The file web.xml
gets automatically created while creating the deployment profile.
This file needs to be edited to include servlet class. You can simply
delete the content of the file and copy the following
<?xml version = '1.0' encoding
= 'UTF-8'?>
<!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>
<display-name>HelloWorldDisplayName </display-name>
<servlet>
<servlet-name>HelloWorldServletName</servlet-name>
<servlet-class>HelloWorld</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>HelloWorldServletName</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
</web-app> |
| Step 9. |
Restart the OC4J server. |
| Step 10. |
Right click on HelloWorld deployment
profile, and choose "Deploy to". Choose the server to which you
want to deploy your servlet .Check for the successful deployment
of the servlet by looking at the deployment console. |
This completes the HelloWorld servlet
deployment, now the sample is ready to
run .
Running the Sample on OC4J :
After deploying the sample, access the
it by using URL like:
http://<IP-address>:<Port>/<path-to-servlet>/<sample
directory>/<main-servlet-file> where
| <IP-address> |
is the IP-address
of the machine on which OC4J is setup |
| <Port> |
is the port on
which OC4J server is running.
(refer to file <J2EE_HOME>\config\default-web-site.xml).
Default is: 8888 |
| <path-to-servlet> |
is the default
directory where all servlets classes are placed.
i.e <J2EE_HOME>\default-web-app\BasicServlets.
Refer to the Step1 in the above Installing and preparing the sample
for simple deployment. This will not be there for WAR
deployment. |
| <sample directory> |
is the directory where the
source files for the samples are placed. |
| <main-servlet-file> |
is the main servlet
file of the sample that is called from the browser. |
For example, the URLs to the sample can
be like:
Simple Deployment:
http://152.69.168.208:8888/servlet/HelloWorld
WAR Deployment (when deployed
using Standard J2EE way)
http://152.69.168.208:8888/HelloWorld/HelloWorld
JDeveloper Deployment (when deployed
using Oracle9i
JDeveloper)
http://152.69.168.208:8888/HelloWorld-HelloWorld-context-root/HelloWorld
This application is just a single call
to HelloWorld servlet; it will display a simple HTML page displaying
the message "Hello Oracle World!".
Please enter your comments about this sample
in the OTN Sample
Code Discussion Forum. |
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