9.4 Creating a Servlet in Place
The code we're developing needs to be in the Tomcat directories to run, and storing the compiled code we generate there is no problem with Eclipse. To see how this works, create a new project,
Ch09_03
. Enter the
name
of the project in the New Java Project dialog and click Next to bring up the second pane of this dialog. To set the default output folder for compiled code, click the Browse button
next
to the Default output folder box to
open
the Folder Selection dialog. Click the Create new folder button, and click the Advanced button in the New Folder dialog. Now select the Link to folder in the filesystem checkbox, and click the Browse button. Browse to the
jakarta-tomcat-4.1.29\webapps\Ch09\WEB-INF\classes
directorythe root directory for compiled servlet codeand click OK, bringing up the New Folder dialog again. In that folder, give this new folder the name output, as you see in Figure 9-5, and click OK.
Figure 9-5. Creating a new output folder
Setting up the output folder this way means that the code we compile will automatically be placed in the
classes
folder (or, in our case, in the
classes\org\eclipsebook\ch09
folder, following the package name we're using). Now create a new class,
Ch09_03
, and enter the code for the servlet in Example 9-4 in it.
Example 9-4. A new servlet
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class ch09_03 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("<HEAD>");
out.println("<TITLE>");
out.println("A Servlet Example");
out.println("</TITLE>");
out.println("</HEAD>");
out.println("<BODY>");
out.println("<H1>");
out.println("Working With Servlets");
out.println("</H1>");
out.println("Developing servlets in place");
out.println("</BODY>");
out.println("</HTML>");
}
}
Finally, add
servlet.jar
to the build
path
as before. When you build this project,
Ch09_03.class
will automatically be stored in the Tomcat
webapps\WEB-INF\classes\org\eclipsebook\ch09
directory, which is exactly where it should go.
We'll also need to edit
web.xml
to install this new servlet. This can be done in Eclipse using a
linked folder
. In this case, we're going to link to the
Ch09/WEB-INF
folder in the Tomcat installation, which holds
web.xml
. To create a linked folder, right-click the
Ch09_03
project and select New
Folder. Click the Advanced button in the New Folder dialog, and select the Link to folder in the filesystem checkbox, then click the Browse button and browse to
jakarta-tomcat-4.1.29\webapps\Ch09\WEB-INF
. Then click OK to bring up the New Folder dialog again, enter the name
WEB-INF
for this new folder in the Folder Name box, and click OK. This creates a new linked folder named
WEB-INF
, and you can access the contents of this folder, including
web.xml
, by opening it in the Package Explorer, as you see in Figure 9-6.
Figure 9-6. Using a linked folder
The
web.xml
to use in this project appears in Example 9-5 (note that
servlet
elements must be grouped together, followed by the grouped
servlet-mapping
elementsthose elements should not be mixed, or Tomcat won't be able to parse the file, which means it won't start).
Example 9-5. The new version of web.xml
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app>
<display-name>Example Applications</display-name>
<servlet>
<servlet-name>Ch09_02</servlet-name>
<servlet-class>org.eclipsebook.ch09.Ch09_02</servlet-class>
</servlet>
<servlet>
<servlet-name>Ch09_03</servlet-name>
<servlet-class>org.eclipsebook.ch09.Ch09_03</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Ch09_02</servlet-name>
<url-pattern>/org.eclipsebook.ch09.Ch09_02</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>Ch09_03</servlet-name>
<url-pattern>/org.eclipsebook.ch09.Ch09_03</url-pattern>
</servlet-mapping>
</web-app>
Enter this new version of
web.xml
now, and restart Tomcat. Eclipse has taken care of all the file handling for us, so there's nothing to copy to the Tomcat directoriesjust navigate to the new servlet's URL,
http://localhost:8080/Ch09/org.eclipsebook.ch09.Ch09_03
, as you see in Figure 9-7.
Figure 9-7. Developing a servlet in place
Getting betternow we've developed a servlet's code entirely in Eclipse. Eclipse has even done the file handling for us.
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