Request Dispatcher

RequestDispatcher defines an object that receives requests from the client and sends them to any resource (such as a servlet, HTML file, or JSP file) on the server. The servlet container creates the RequestDispatcher object, which is used as a wrapper around a server resource located at a particular path or given by a particular name.

This interface is intended to wrap servlets, but a servlet container can create RequestDispatcher objects to wrap any type of resource.

Method Summary
 forward Forwards a request from a servlet to another resource (servlet, JSP file, or HTML file) on the server.
 include Includes the content of a resource (servlet, JSP page, HTML file) in the response.

Create New Dynamic Web Project

Step 1.1 Create New Project

Go to File->New->Others… Select Dynamic Web Project under Web category then click Next. Type ServletDemo or whatever name you want in the Project name field.

Step 1.2 Configure Target Runtime

  • Click New Runtime… button under Target Runtime.
  • Select Apache Tomcat v7.0. Click Next.
  • Click Browse button to specify Tomcat Server installation directory. The select the folder then click Ok.
  • Click Installed JREs… button to add/remove or edit JRE definition. Remove existing one; then click Add button to configure new one. Select Standard VM; then click Next. Click Directory button to select the root folder of JDK installation. Select the folder then click Ok. Click Finish.
  • Check the JDK then click Ok.
  • Change JRE to the JDK then click Finish.
  • Click Finish the finish the project creation.

In this example, to save time; I use annotation servlet so we don’t need to register in web.xml. I’ll explain in other topic of this tutorial.

Forward

Step 2 Create Servlet 1 Class

  • Right click to the project or src folder, select New -> Class from the menu.
  • In Java package, enter info.java.tips.servlet.
  • In Class Name, type Servlet1 or any name you want.
  • Click Finish.
  • Add extends HttpServlet to the class.
  • Implement doGet() method.

This servlet forwards to the other servlet. After forwarding, the user request content will remain and be retrievable from the other servlet.

Step 3 Create Servlet 2 Class

Step 4 Clean & Build

Clean & build the project to clean old classes file (if any) & force the IDE to recompile java code.

  • Go to Project on menu bar; select Clean…
  • Select Clean all projects (default)
  • Click Ok to proceed clean & build.

Step 5 Configure Tomcat

Select Servers window; in case it’s not there, go to Windows -> Show View-> Others… Select Server -> Servers; then click Ok.

If this is the first time you are creating a server, in the Servers area you will see a link as No servers are available click this link to create a new server. Click the link.

Define a New Server window will be opened, In Select the server type. Select Apache -> Tomcat v7.0 Server. Then click Finish.

Step 6 Deploy The Application

  • Right click to the Tomcat Server select Add and Remove.
  • Move the application (ServletDemo) from Available column to Configured. Then click on Finish to deploy it to tomcat server.

Step 7 Start Tomcat Server

Right click on the tomcat server and choose Start or simply click on the green start icon to start the server.

Step 8 Run The Servlet

We assume that you install tomcat on default port (8080) and project name is ServletDemo. Open web browser and type:

http://localhost:8080/ServletDemo/Servlet1?test=test attribute

Output

Include

Similarly, change the code at line 16 in Servlet1.class  from

to

Deploy & run the servlet

  • No need to stop the tomcat server
  • Clean & build the project to re-compile the application
  • Open web browser and run the below URL (refresh if you’re opening it).

http://localhost:8080/ServletDemo/Servlet1?test=test attribute