Transcript No Slide Title

Chapter 2
How to install and
use Tomcat
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 1
Objectives
Applied
 Install and configure Tomcat so it runs on your own PC.
 Start Tomcat from a DOS prompt window, and shut it down
from this window.
 Turn on servlet reloading so you don’t have to stop and restart
Tomcat every time you want to change and test a servlet.
 Use your browser to enter a URL that accesses an HTML
document, JSP, or servlet.
 If a port conflict occurs, change the port that’s used by Tomcat.
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 2
Objectives (continued)
Knowledge
 Describe two common errors that occur after you enter a URL into
a browser.
 In general terms, describe the directory structure of a Web
application that’s defined by the J2EE specfication.
 In general terms, describe the deployment descriptor of a web
application.
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 3
The Apache web site address
www.apache.org
How to install Tomcat from the CD that comes
with the book
1. Put the CD that comes with this book into your CD drive, and
navigate to the Tomcat 4.0 directory.
2. Use a zip program such as WinZip to extract the files from the zip
file named jakarta-tomcat-4.0.1. If you don’t have WinZip, you can
get it free from www.winzip.com.
3. If necessary, move the jakarta-tomcat directory to the C drive.
4. Rename the jakarta-tomcat directory to tomcat.
5. Copy the servlet.jar file from the C:\tomcat\common\lib directory to
the C:\j2sdk1.4.0\jre\lib\ext directory.
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 4
How to install Tomcat on your own PC
 The directory that holds the files for Tomcat is known as the
Tomcat home directory. By default, this directory is jakartatomcat-4.0.X.
 To save yourself typing, we recommend that you rename this
directory to tomcat.
 The servlet.jar file contains the Java classes that you need for
developing servlets. By copying this JAR file from the tomcat
subdirectory to the SDK subdirectory, you make the classes
available to the SDK.
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 5
The file structure of Tomcat
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 6
The subdirectories of Tomcat
Directory
bin
classes
common
conf
lib
logs
server
webapps
work
Java Servlest and JSPCH02
Description
The binary executables and scripts
Unpacked classes that are available to all web applications
Classes available to internal and web applications
Configuration files
JAR files that contain classes that are available to all web
applications
Log files
Internal classes
Web applications
Temporary files and directories for Tomcat
© 2003, Mike Murach & Associates, Inc.
Slide 7
The files of Tomcat
File
readme.txt
running.txt
Java Servlest and JSPCH02
Description
General information about Tomcat
Instructions for installing, starting, and stopping
Tomcat
© 2003, Mike Murach & Associates, Inc.
Slide 8
Notes on Tomcat
 Since Tomcat is an open-source project, developers who work on
Tomcat can download the source distribution for Tomcat, modify
the source code, and build Tomcat from the source code.
 Developers who develop web applications only need to download
and install the binary for Tomcat distribution.
 To make the classes within a JAR file available to Tomcat so you
can run an application that uses them, you can put the JAR file in
Tomcat’s common\lib directory.
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 9
The catalina batch file opened for editing
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 10
How to set the JAVA_HOME environment variable
1. Use a text editor like Notepad or TextPad to open the catalina.bat
file located in the c:\tomcat\bin directory.
2. Scroll down to the section named “Save Environment Variables
That May Change.”
3. After the last Set command, enter
set JAVA_HOME=c:\j2sdk1.4.0
where c:\j2sdk1.4.0 is the directory that contains the SDK that’s
installed on your system.
4. Save your changes to the catalina.bat file.
5. If necessary, stop and restart Tomcat.
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 11
The Properties dialog box for the startup batch file
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 12
How to change the memory settings for the
startup batch file
1. Start the Windows Explorer and navigate to the bin directory of
Tomcat.
2. Right-click on the startup batch file and select the Properties option.
3. From the Properties dialog box, select the Memory tab.
4. Change the Initial Environment option from Auto to 4096.
5. Click on the OK button.
How to change the memory settings for the
shutdown batch file
 Follow the steps shown above, substituting shutdown for startup.
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 13
The server.xml file
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 14
How to turn on servlet reloading
1. Use the Windows Explorer to navigate to Tomcat’s conf directory
and open the server.xml file in a text editor.
2. Scroll down to the comment shown above and insert the following
statement below it:
<DefaultContext reloadable="true"/>
3. Save the changes to the server.xml file
4. If necessary, stop and restart Tomcat.
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 15
What is servlet reloading
 If servlet reloading isn’t on, which is the default setting, you have
to stop and restart Tomcat each time that you change one of the
classes that’s in memory.
 If you turn servlet reloading on, Tomcat checks the modification
dates of the classes in memory and automatically reloads the ones
that have changed so you don’t have to stop and restart Tomcat
each time a class changes.
 Although this is useful in development, it can cause performance
problems in a production environment.
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 16
What is the server.xml file
 The server.xml file is an XML file that controls how the
Tomcat engine is configured.
 Tomcat reads this file every time it starts to configure itself.
 You can use a text editor to edit this file.
 Then, you can stop and restart Tomcat to put the changes into
effect.
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 17
DOS commands for starting Tomcat
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 18
The console that Tomcat displays when it’s
running
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 19
How to use the DOS Prompt window to start and
stop Tomcat
1. Open a DOS Prompt window and use the cd command to change
the current directory to Tomcat’s bin directory.
2. To start Tomcat, type “startup” and press the Enter key. To stop
Tomcat, type “shutdown” and press the Enter key.
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 20
What to do if Tomcat doesn’t start because it’s
“out of environment space”
 First, make sure that you did the procedures in figure 2-4 correctly.
 If you did and you’re using Windows 95, you can then set these
variables this way:
(1) click on the Title bar of the DOS Prompt window
(2) select Properties from the shortcut menu
(3) click on the Memory tab
(4) change the Initial environment setting to 4096.
 After you close and reopen the DOS Prompt window, this should
fix the problem.
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 21
A web browser that displays a web page
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 22
The components of an HTTP URL
How to view a web page via an HTTP URL
1. Start Tomcat.
2. Start your web browser.
3. In the Address text box (for the Internet Explorer) or Location text
box (for Netscape), type a URL and press Enter.
How to specify the host and port in the URL
 When Tomcat is running on your local machine, you can use the
“localhost” keyword to specify the host machine.
 The default port for Tomcat is 8080. If another application is
already using this port, you can change the default port.
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 23
A web browser that displays a directory listing
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 24
The Internet Explorer’s error page
Why this error may occur
 If the browser displays a message like this, the HTTP request isn’t
connecting with a web server.
 To solve this problem, make sure that the Tomcat engine is
running, and make sure that you’ve entered a valid URL.
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 25
Tomcat’s default 404 error page
Why this error may occur
 If the browser displays a Tomcat error page like this, Tomcat is
receiving the HTTP request, but it can’t find the requested
resource.
 To solve this problem, make sure that you’ve entered the path and
filename of the URL correctly.
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 26
The server.xml file
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 27
How to change the port that’s used by Tomcat
1. Use the Windows Explorer to navigate to Tomcat’s conf directory
and open the server.xml file in a text editor.
2. Replace all instances of the current port, which is 8080 by default,
to a four-digit number that’s greater than 1024 or to 80. To do this,
you may want to use the Find and Replace feature of your text
editor.
3. Save the changes to the server.xml file.
4. Stop and restart Tomcat.
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 28
How to work with ports in Tomcat
 If you have a port conflict with another application, you can
change the default port from 8080 to a four-digit number that’s
greater than 1024.
 If you don’t enter a port when you specify a URL, your browser
will use port 80. As a result, if you change Tomcat’s default port
from 8080 to 80, you don’t need to enter a port when entering a
URL in the browser. Then, assuming that there isn’t a port
conflict, you can view a web page by entering a URL like this:
http://localhost/examples/servlets
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 29
The index page for the webapps\murach directory
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 30
How to install the web applications that are on the
book’s CD
1. From the root directory of the CD, double-click on the file named
Install.exe and respond to the dialog boxes that follow. This will
install the source code and test files in the c:\murach\webapps
directory.
2. Copy the c:\murach\webapps\murach directory and all its
subdirectories to c:\tomcat\webapps.
3. Copy the c:\murach\webapps\musicStore directory and all its
subdirectories to c:\tomcat\webapps.
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 31
How to view and run the web applications that are
on the book’s CD
 To view the index page for all applications stored under the
murach directory, start Tomcat and access
http://localhost:8080/murach from your browser.
 To view the index page for the musicStore directory, start Tomcat
and access http://localhost:8080/musicStore from your browser.
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 32
The directory structure for a web application
named musicStore
c:\tomcat
webapps
musicStore (the document root directory for the application)
admin (JSP and HTML files for the admin section)
cart (JSP and HTML files for the cart section)
download (JSP and HTML files for the download section)
WEB-INF (contains the web.xml file for the application)
classes
music
admin (servlets for the admin section)
business (Java classes for business objects)
cart (servlets for the cart section)
data (Java classes for database access)
download (servlets for the download section)
etc (data files and other miscellaneous files)
lib (JAR files that contain Java classes)
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 33
A summary of the directories and files for a web
application
Directory
document root
\WEB-INF
Java Servlest and JSPCH02
Description
The document root directory is the root
directory for a web application. This directory
typically contains the index file for the
application. In addition, this directory or its
subdirectories contain the HTML and JSP files
for the application.
This directory contains a file named web.xml. It
can be used to configure the servlets and other
components that make up the application.
© 2003, Mike Murach & Associates, Inc.
Slide 34
A summary of the directories and files for a web
application (continued)
Directory
\WEB-INF\classes
\WEB-INF\lib
Java Servlest and JSPCH02
Description
This directory and its subdirectories contain the
servlets and other Java classes for your
application that aren’t compressed into JAR
files. If you’re using Java packages, each
package must be stored in a subdirectory that
has the same name as the package.
This directory contains any JAR files that
contain Java classes that are needed by this web
application, but not by other web applications.
© 2003, Mike Murach & Associates, Inc.
Slide 35
How to use the directories and files in a web
application
 A Java web application is a hierarchy of directories and files in a
standard layout defined by the J2EE specification.
 To organize your Java class files, you can store them in packages.
A package of classes must be stored within a subdirectory of the
WEB-INF\classes directory.
 If you need to make classes within a JAR file available to more
than one web application, you can put the JAR file in Tomcat’s
webapps\common\lib directory.
 If you need to make classes within a JAR file available to a single
web application, you can put them in the WEB-INF\lib directory
for that application.
 You can use the WEB-INF\etc directory to store any files that you
don’t want users to be able to access.
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 36
A web.xml file
<?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>
<servlet>
<servlet-name>EmailResponse</servlet-name>
<servlet-class>email.EmailServlet</servlet-class>
<init-param>
<param-name>filename</param-name>
<param-value>UserEmail.txt</param-value>
</init-param>
</servlet>
</web-app>
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 37
What is the web.xml file
 Every web application requires a web.xml file in the WEB-INF
directory. This file is known as the deployment descriptor for the
web application.
What the web.xml file can do
 Provide an alias for a servlet class so you can call a servlet using a
different name.
 Enable servlet mapping so you can call a servlet using any URL
or URL pattern.
 Define initialization parameters for a servlet or the entire
application.
 Define error pages for an entire application.
 Provide security constraints to restrict access to certain web pages
and servlets.
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 38
The directory structure for the book applications
c:\tomcat
webapps
murach (the document root directory for the book applications)
email4 (JSP and HTML files for chapter 4)
email5 (JSP and HTML files for chapter 5)
email6 (JSP and HTML files for chapter 6)
cart7 (JSP and HTML files for the cart application in chapter 7)
download7 (JSP and HTML files for the download application in chapter 7)
styles (style sheets for HTML and JSP pages)
index.htm (index page for the book applications)
WEB-INF (contains the web.xml file for the applications in chapters 3-15)
classes
business (Java classes for business objects)
data (Java classes for IO and database access)
email5 (servlets for chapter 5)
email6 (servlets for chapter 6)
cart7 (servlets for the cart application in chapter 7)
download7 (servlets for the download application in chapter 7)
util (Java helper classes)
etc (data files and other miscellaneous files)
lib (JAR file for the MySQL database driver)
Java Servlest and JSPCH02
© 2003, Mike Murach & Associates, Inc.
Slide 39