Entry
Java: Servlet: Create: Simple: How to create a Java servlet that displays 'Hello world'? [Tomcat v6]
Apr 22nd, 2007 10:18
Knud van Eeden,
----------------------------------------------------------------------
--- Knud van Eeden --- 21 April 2007 - 16:11 -------------------------
Java: Servlet: Create: Simple: How to create a Java servlet that
displays 'Hello world'? [Tomcat v6]
---
Steps: Overview:
1. Install Tomcat
(in general a web server that can handle servlets)
2. -Download and install Java JDK
(or similar Java Enterprise Edition JxEE)
3. -Create your servlet source code using your favorite texteditor
(inside the servlet put source code to generate (=print) a HTML
page)
--- cut here: begin --------------------------------------------------
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class HelloWorld extends HttpServlet {
public void doGet( HttpServletRequest request, HttpServletResponse
response )
throws IOException, ServletException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<html>");
out.println("<body>");
out.println("<head>");
out.println("<title>Hello World!</title>");
out.println("</head>");
out.println("<body>");
out.println("<h1>Hello World!</h1>");
out.println("</body>");
out.println("</html>");
}
}
--- cut here: end ----------------------------------------------------
4. Save this as
HelloWorld.java
(e.g. in the c:\temp\ directory)
5. Compile and debug it
1. -Run javac.exe located in your Java JDK bin directory with this
parameters
cd C:\Program Files\Java\jdk1.6.0_01\bin\
javac.exe -classpath "<path to your JDK>;<path to Tomcat
servlet-api.jar>" <your filename>
E.g. (all on one line)
javac.exe -classpath "C:\Program
Files\Java\jdk1.6.0_01;C:\tomcat\apache-tomcat-6.0.10\lib\servlet-
api.jar" c:\temp\HelloWorld.java
or more general
javac.exe -classpath "%JAVA_HOME%;%CATALINA_HOME%\lib\servlet-
api.jar" c:\temp\HelloWorld.java
2. -This will create a file
HelloWorld.class
in the same directory, when you have compiled
successfully
3. -Copy this file
HelloWorld.class
to your Tomcat class directory
(by default in a 'classes' subfolder of the WEB-INF folder of
the Tomcat ROOT directory)
===
E.g. (all on one line)
md "C:\tomcat\apache-tomcat-6.0.10\webapps\ROOT\WEB-
INF\classes\"
copy c:\temp\HelloWorld.class "C:\tomcat\apache-tomcat-6.0.10
\webapps\ROOT\WEB-INF\classes\"
4. -Backup and edit the file
web.xml
in the directory
"C:\tomcat\apache-tomcat-6.0.10\webapps\ROOT\WEB-INF\web.xml"
--- cut here: begin --------------------------------------------------
<?xml version="1.0" encoding="ISO-8859-1"?>
<!--
Licensed to the Apache Software Foundation (ASF) under one or more
contributor license agreements. See the NOTICE file distributed with
this work for additional information regarding copyright ownership.
The ASF licenses this file to You under the Apache License, Version
2.0
(the "License"); you may not use this file except in compliance with
the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
implied.
See the License for the specific language governing permissions and
limitations under the License.
-->
<web-app xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_5.xsd"
version="2.5">
<display-name>Welcome to Tomcat</display-name>
<description>
Welcome to Tomcat
</description>
</web-app>
--- cut here: end ----------------------------------------------------
5. -Add the following tag to it, giving the name of your servlet
--- cut here: begin --------------------------------------------------
<servlet>
<servlet-name>HelloWorld</servlet-name>
<servlet-class>HelloWorld</servlet-class>
</servlet>
--- cut here: end ----------------------------------------------------
6. -Add also the following tag to it, giving the URL to your
servlet
(this is in general /servlet/<your servlet name>)
--- cut here: begin --------------------------------------------------
<servlet-mapping>
<servlet-name>HelloWorld</servlet-name>
<url-pattern>/servlet/HelloWorld</url-pattern>
</servlet-mapping>
--- cut here: end ----------------------------------------------------
7. -So all together your new web.xml becomes
--- cut here: begin --------------------------------------------------
<?xml version="1.0" encoding="ISO-8859-1"?>
<!--
Licensed to the Apache Software Foundation (ASF) under one or more
contributor license agreements. See the NOTICE file distributed with
this work for additional information regarding copyright ownership.
The ASF licenses this file to You under the Apache License, Version
2.0
(the "License"); you may not use this file except in compliance with
the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
implied.
See the License for the specific language governing permissions and
limitations under the License.
-->
<web-app xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_5.xsd"
version="2.5">
<display-name>Welcome to Tomcat</display-name>
<description>
Welcome to Tomcat
</description>
<servlet>
<servlet-name>HelloWorld</servlet-name>
<servlet-class>HelloWorld</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>HelloWorld</servlet-name>
<url-pattern>/servlet/HelloWorld</url-pattern>
</servlet-mapping>
</web-app>
--- cut here: end ----------------------------------------------------
6. -*Important*
If you save this web.xml file make sure there are no empty lines
at the top, or your Tomcat will give a lot of (XML parse)
errors
7. Run this servlet file in your browser
1. -First make sure your servlet server program (=Tomcat) is
running (e.g. by running its startup.bat batch file in the
Tomcat 'bin' directory)
-Thus typing in your browser the URL
http://localhost:8080
should show the Tomcat home page
2. -To test your HelloWorld.class servlet file locally on your
computer, open your browser, and type the URL:
http://localhost:8080/servlet/HelloWorld
===
Note:
1. -You should use forward slashes in the URL
Thus this is OK
http://localhost:8080/servlet/HelloWorld
but using backward slashes is not OK
(that will give error 'Page can not be displayed')
http://localhost:8080\servlet\HelloWorld
2. -In the URL, put only the name of the servlet file (e.g.
'HelloWorld') but without the .class extension
Thus this is OK
http://localhost:8080/servlet/HelloWorld
but this is not OK (will give error
HTTP Stastus 404 'The requested resource is not available')
http://localhost:8080/servlet/HelloWorld.class
3. -You should see in your browser
Hello World!
===
Tested successfully on
Microsoft Windows XP Professional (service pack 2),
running
Tomcat v6
Java JDK v1.6
===
Internet: see also:
---
Language: Computer: Java: Servlet: Link: Overview: Can you give an
overview of links?
http://www.faqts.com/knowledge_base/view.phtml/aid/40576/fid/778
----------------------------------------------------------------------
