JSP Deployment

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Getting Started With Tomcat

1. If you do not alreaady have Java on your machine, download and install Java Development Kit. Note: You should verify which JDK version is supported by the version of Tomcat you are using.
   • Download Java EE from http://java.sun.com/
   • Install JDK and JRE according to the instructions included with the release.
   • Set the environment variable JAVA_HOME to the directory where you installed the JDK release:
     • for Window
     • for Mac
   • You may need to restart your computer.
   
   
2. Download Tomcat "Core" zip file from: http://tomcat.apache.org/.
   
   
3. Unzip the apache-tomcat zip file
   • (for Window) Assuming you unzipped it on drive C, the path is C:\apache-tomcat
   • (for Mac) Assuming you unzipped it in Applications folder, the path is Applications/apache-tomcat
   
   
4. Startup Tomcat
   • (for Window)
     • Double click C:\apache-tomcat\bin\startup.bat, or
     • Use a terminal, go to C:\apache-tomcat\bin\   then execute startup.bat
   • (for Mac)
     • Use a terminal, go to Applications/apache-tomcat/bin/   then execute ./startup.sh
   After startup, the default web applications included with Tomcat will be available by browsing http://localhost:8080/
   
   
5. Shutdown tomcat
   • (for Window)
     • Double click C:\apache-tomcat\bin\shutdown.bat, or
     • Use a terminal, go to C:\apache-tomcat\bin\   then execute shutdown.bat
   • (for Mac)
     • Use a terminal, go to Applications/apache-tomcat/bin/   then execute ./shutdown.sh

Setup Tomcat in Eclipse environment

Note: This is optional. You may use any IDEs of your choice with tomcat installation from the previous step.

Requirements: Tomcat, Eclipse, JDK, and JRE

1. Open Eclipse
2. Go to the Servers tab.
   
   
   If the Servers tab does not appear on the screen, open the view using menu bar Window > Show View > Servers
   
   
   
3. Under the Servers tab, right click and select New > Server
4. Select the version of your Tomcat. You may use the default server name or change it. Then click Finish
   
   
   
5. Once the server is setup, to start the server, right click on the server name, then select Start
   
   
   Note: When you right click on the servlet .java file and select Run As > Run on Server, Eclipse will prompt a window to start the server. You can also choose to have the server starts automatically as you run the servlet.
   
   
6. To stop the server, right click on the server name, then select Stop
   
   
   

Working with JSP

Creating a JSP (.jsp file)
• You may use any IDEs that support Java web develoment such as Eclipse WTP, IntelliJ, and NetBeans.
• Because a JSP is built on top of a Java servlet, it is necessary to include sevlet-api.jar in classpath. Some IDEs automatically include a path to servlet-api.jar while some require that you set class path to servlet-api.jar
  
  
• For Eclipse user
  • Create a dynamic web project (depending on the version of your Eclipse) by selecting Create a new Java EE Web Project or using the menu bar File > New > Dynamic Web Project
    
    
    
  • Enter your project name (let's keep default configuration), then click Next and Next to configure Web Module. Note: You may choose to click Finish and generate web.xml to configure Web Module later.
    
    
    On the Web Module window, select Generate web.xml deployment descriptor. Note: If you choose to manually create web.xml later, you may leave the checkbox blank.
    
    
    
  • Under your newly created project, right click on the WebContent folder, select New > JSP file to create a new .jsp file.
    
    
    Enter the name of your JSP in File name. If you choose to have a package for your JSPs, right click on the WebContent, select New > Folder, enter the folder (or package) name in the Folder name.
    
    
    Then, right click on the newly created folder, select New > JSP file to create a new .jsp file.
    
    Open the newly create JSP, if there are errors (for example, as shown in the following figure), you need to add servlet-api.jar to your project.
    
    
    
  • To add servlet-api.jar to your project
    • Open Project Properties by
      • Right click on the project name and then Properties, or
      • Use a menu bar Project > Properties
    • Select Java Build Path
    • Select Libraries tab
    • Press Add External JARs... button
      
      
      
    • Navigate to the location where you save servlet-api.jar. Note: By default, servlet-api.jar is part of Apache Tomcat and is usually in
      • (for Window) C:\apache-tomcat\lib
      • (for Mac) Applications/apache-tomcat/lib
    • Select servlet-api.jar
    • Press Open button.
      • servlet-api.jar should appear under JARs and class folders on the build path panel
        
        
        
Writing code / implementing your JSP
JSP syntax: <% X ... %> where X is one of the following:
• Directive: Global information for page, language, import statement, etc.
• Scripting elements (Java code): Declarations, Scriptlets, Expressions
• Actions: To modify runtime behavior

If you choose to deploy your JSP in a package, you do not need to add a package command in your code (unlike a Java program where you explicitly add package package-name; at the beginning of the file). Tomcat will add that for you when it converts the JSP to a Java servlet.

Note: When a JSP is accessed through a web browser, Tomcat decides whether to transforms a JSP into its Java servlet version (.java file) and then compiles the Java servlet (i.e., resulting in a .class file). We do not need to compile a JSP file.


Deploying a JSP
To deploy your JSP, follow these steps:
• (for Window) Go to C:\apache-tomcat\webapps
• (for Mac) Go to Applications/apache-tomcat/webapps
  
  
• Create a project (i.e., context) directory for your JSPs the same way you did for servlets, /tomcat/webapps/project-name/. You may create a directory the way you normally do, using the features available on your machine. Alternatively, if you use a terminal,
  • create your project directory:
           mkdir /tomcat/webapps/project-name/
  • then copy your JSP file (e.g., file-name.jsp) into that directory:
           cp file-name.jsp /tomcat/webapps/project-name/
  • (optional) You can create a symbolic link from your home directory to your context
           cd
       ln -s /tomcat/webapps/project-name/ name-of-link
  
  
• Assume you give your context name as cs4640:
  
  

  Directory	Contains
  \cs4640	This is the root directory of the web application. All JSP and HTML files are stored here.
  \cs4640\WEB-INF\classes	This directory is where servlet and utility classes are located.
  \cs4640\WEB-INF	This directory contains all resources related to the application that are not in the document root of the application. This is where your web application deployment descriptor (web.xml) is located. Note that the WEB-INF directory is not part of the public document. No files contained in this directory can be served directly to a client.
  \cs4640\WEB-INF\lib	This directory contains Java Archive (JAR) files that the web application depends upon. For example, this is where you would place a JAR file that contains a JDBC driver.

For Eclipse user:
• Simply put the JSP files in WebContent. When you run the JSP file, Eclipse automatically deploys and runs it.
  
  
Accessing / running a servlet
• To access via a web browser
  • Enter a URL similar to http://localhost:8080/project-name/file-name.jsp
• To access through Eclipse
  • Right click on the JSP name (.jsp file), select Run As > Run on Server. Eclipse will access the servlet using a virtual browser.

Remember that the first time you access the URL, the servlet engine will translate your JSP file into a Java servlet class, compile the class, then run it as a servlet. You will see a noticeable delay. The servlet engine also translates and compiles if you change the JSP file (if the timestamp of the .jsp is newer than the timestamp of the .class file).


Locating a Java servlet of the JSP
• Assume your JSP is X.jsp, typically the servlet Java file (X_jsp.java) and servlet class file (X_jsp.class) are in /tomcat/work/Catalina/localhost/project-name/org/apache/jsp/
• However, depending on your configuration (e.g., if you run new versions of Tomcat from Eclipse, assuming you rely on the default configuration), X_jsp.java and X_jsp.class may not be in the default Catalina directory. You may use a terminal to find the file:
          find . | grep "X_jsp.java"


Working with Java Beans or Other Java classes
• JSPs often need to interface with Java Beans or other Java classes, and you need to put the classes in the right directory. The key to the linking is that the JSP is converted to a Java servlet, which is then compiled by the servlet engine. Therefore the bean's package directory has to be in a directory that is in the Java CLASSPATH of the servlet engine, or else it will not be found when the JSP is compiled. Conveniently, you can put Java classes in the same directory with your servlets:
          /tomcat/webapps/project-name/WEB-INF/classes/
  
  
• The bean class has to be in a package, so you need to create one. (If you have already done this for your servlets, just skip this step.) Each Java package has its own subdirectory, so create a subdirectory with your package-name under the classes/ directory. Assume your package name is examples, your bean class is named mybean.java, and it is in your home directory. Modify mybean.java to add the statement package examples; in the first line. Then create the package:
          cd /tomcat/webapps/project-name/WEB-INF/classes
        mkdir examples
        cp ~/mybean.class examples
  
  
• Please note that you can access any Java class from a JSP
• With that set up, you need to do the following to use a Java bean from a JSP. Again, assume your bean is called "mybean", and the JSP is called "myUseBean.jsp":
  1. Import the bean into myUseBean.jsp:
           <%@ page import="examples.mybean" %>
  2. Declare an object of type mybean named Val, set the scope (based on the nature of your web application):
           <jsp:useBean id="Val" class="examples.mybean" scope="page" />
  3. Copy your JSP file into the JSP directory above.