Servlet requestdispatcher forward and include method. In this tutorial you will see that how getservletcontext method is used in servlet. The same getrequestdispatcher string path method exist in. The getrequestdispatcher method of servletrequest interface returns the object of requestdispatcher.
A requestdispatcher object can forward a clients request to a resource or include the resource itself in the response back to the client. Requestdispatcher forward method forwards a request from a servlet to another resource servlet, jsp file, or html file on the server. This method forwards a request from a servlet to another resource servlet, jsp file or html 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. That way you can merge the output of servlets into a single repsonse.
It is like a method call where the calling method gains data from the called method. Forwards a request from a servlet to another resource servlet, jsp file, or html file on the server. If a servlet is invoked using the forward or the include method of requestdispatcher, which methods of the servlets request object can access the request attributes set by the container. The requestdispatcher interface defines an object that receives the request from client and dispatches it to the resource such as servlet, jsp, html file. New request is created for the destination resource. The request is dispatched to that corresponding servlet.
Introduction to resquest dispatcher in servlet studytonight. Java servlet requestdispatcher tutorial examples java code geeks. It works at client side because it uses the url bar of the browser to make another request. This interface defines an object that receives request from the client and sends them to any resource which can be servlet,html or jsp. There is a little difference between calling the forward and include method. Forwarding and including response from other servlets. The request method getrequestdispatcher can be used for referring to local servlets within single webapp. The requestdispatcher is created from the request because it. To get the particular servlet we will use the following method from servlet config object. By calling getrequestdispatcher method of servletrequest.
This method allows one servlet to do preliminary processing of a request and. What is the defferent between getnameddispatcher and. The web container calls the service method of the servlet for every request. The following are jave code examples for showing how to use forward of the javax. It does not depend on the clients request protocol since the forward method is provided by the servlet container. Requestdispatcher from servletrequest vs servletcontext. Hi, the difference between the getrequestdispatcher method of servletcontext and that of servletrequest is that you can pass a relative path to the getrequestdispatcher method of servletrequest but not to the getrequestdispatcher method of servletcontext.
The servlet container creates the requestdispatcher object, which is used as a. Java requestdispatcher dispatching requests in java web. To understand the difference between these two methods, lets take an example. Using this configuration file with the requestdispatcher object with the forward method we can forward the contents of one. The mainly difference between these methods is that the getnameddispatcher method from servletcontext interface does not add some request attributes to the request operation. This interface implements methods to forward a request or include output from another active source such as another servlet. How to use requestdispatcher in servlet bunks allowed. Defines an object to provide client request information to a servlet. For a requestdispatcher obtained via getrequestdispatcher, the servletrequest object has its path elements and parameters adjusted to match the path of the target resource. In this case the control will be in page x till it encounters forward, after this the control will be transferred to page y. Jsp files are compiled to custom servlets that write the html to the response. It enables one servlet to do prelude processing of a request and another resource to create the response.
In both the programs, getrequestdispatcher string path of servletrequest is used to obtain an object of requestdispatcher. In order to dispatch the request we need to perform these tasks. Another difference between the two is that path of the getrequestdispatcher string path of the servletrequest interface cannot extend outside the current servlet context whereas getrequestdispatcher string path of the servletcontext can use the getcontextstring uripath method to obtain requestdispatcher for resources in foreign contexts. Requestdispatcher is an interface that enables the servlet container to dispatch the request from a web application to another within the same context. Difference between forward and sendredirect in servlet. Requestdispatcher javatm ee 7 specification apis oracle docs. Requstdispatcher can be get using getrequestdispacther method of servletrequest andor from the servletcontext. Infact, requestdispatcher object can be obtained in another way also using javax.
Get a requestdispatcher object use the forward method or include method of requestdispatcher. Thus, a requestdispatcher performs a very important role in java mvcw architecture since it can serve as the mechanism for the controller servlet to pass the. The getservletcontext method and its uses with example. Requestdispatcher method call with parameter oracle. It forwards the request from one servlet to another resource such as servlet, jsp, html file. The include method defined in the requestdispatcher class can be used to access one servlet from another. Requestdispatcher interface this interface is present in the javax. A servlet can get an object that implements this interface from the servletcontext by calling the getrequestdispatcher method if the servlet engine can it should provide a wrapper object which implements this interface when a servlet calls getrequestdispatcher.
This interface is intended to wrap servlets, but a servlet container can create requestdispatcher objects to wrap any type of resources. The getrequestdispatcher method of servletrequest interface returns the. An application could be served by many servlets which are configured in a deployment descriptor file, web. How do the getrequestdispatcher and forward methods work. This method sets the dispatcher type of the given request to dispatchertype. In the above sample code, when exception is raised in the doget, method of dbsrvservlet program, the servlet errsrv program will be executed automatically because of the rd. Interfaces that extend servletrequest can provide additional protocolspecific data for example. By calling getrequestdispatcher method of servletcontext. How to get the object of requestdispatcher the getrequestdispatcher method of servletrequest interface returns the object of requestdispatcher. The following are jave code examples for showing how to use getrequestdispatcher of the javax.
Requestdispatcher methods lets take a look at the methods part of javax. Now, open up the eclipse ide and lets see how the requestdispatcher interface is used to forward or include the response. In this article, we are going to understand how to forward the contents of one servlet to another servlet using the forward method of requestdispatcher object. Servlet context based getrequestdispatcher method can used of referring servlets from other web applications deployed on same server. The requestdispatcher interface provides two methods. If we want to specify initialization parameters on to the servlet config. A resource can be another servlet, or an html file, or a jsp file, etc. In lieu of this method, servlets can share information using the servletcontext class and can perform shared business logic by invoking methods on common non servlet classes. This interface is intended to wrap servlets, but a servlet container can create. In the case of two servlets, servlet1 will include the response of servlet2 and servlet1 is reverted back to.
To get the reference of the servlet config object we will use the following method from servlet interface. As you can see in the above figure, response of second servlet is included in the response of the first servlet that is being sent to the client. The activated servlet has access to the same request as the servlet calling it, and will write to the same response as your current servlet. We have seen two programs with include and forward methods of requestdispatcher. We are going to describe requestdispatcher in java. For a requestdispatcher obtained via getrequestdispatcher, the servletrequest object has its path elements and parameters. This method will be permanently removed in a future version of the java servlet api.