Getrequestdispatcher method in servletconfig

In this article, we are going to understand how to include an output from another servlet into the current servlet using the include method of requestdispatcher object. Today, we are going to understand how to forward the contents of one servlet to another servlet using the forward method of requestdispatcher object. You can also think of a requestdispatcher object as a wrapper for the resource located at a given path that is supplied as an argument to the getrequestdispatcher method. Example of servletconfig in java servlet, how to use.

The examples are extracted from open source java projects. The getrequestdispatcher method of servletrequest interface returns the object of requestdispatcher. Similarly for every webapplication webcontainer creates one servletcontext object to maintain application level configuration information. This method returns the all parameter names from the web. The name may be provided via server administration, assigned in the web application deployment descriptor, or for an unregistered and thus unnamed servlet instance it will be the servlets class name. This is at the end of the dopost, where i am finished and returning it. Difference between servletconfig and servletcontext. Difference between forward and sendredirect in servlet. For every servlet, web container will create one servletconfig object to maintain servlet level initialization parameter. The servletcontext class provides two methods getrequestdispatcherstring. What is the defferent between getnameddispatcher and getrequestdispatcher. Requestdispatcher interface defines an object that receives the request from client and dispatches it to the resourcessuch as servlet, jsp, html file.

Using the requestdispatcher object with the forward method we can forward the contents of one servlet to another servlet. There is one context per web application per java virtual machine. These examples are extracted from open source projects. To overcome this, init method is used for initialization instead of declaring a constructor. The requestdispatcher class enables your servlet to call another servlet from inside another servlet. Example demonstrating usage of requestdispatcher in this example, we will show you how requestdispatcher is used to forward or include response of a resource in a servlet. This interface can also be used to include the content of another resource also. What is the difference between the getrequestdispatcherstring and getnameddispatcherstring methods in the servletcontext class. This method returns a requestdispatcher object for the resource. Using getparameter method all values can also be retrieved. Introduction to servletconfig interface studytonight. Requstdispatcher can be get using getrequestdispacther method of servletrequest andor from the servletcontext. This method allows servlets to gain access to the context for various parts of the. The genericservlet class implements the servlet and.

Nullpointerexception with requestdispatcher oracle community. In order to dispatch the request we need to perform these tasks. Servletcontexts getcontext method servlets forum at. Method of genericservlet class used to return the object of servletcontext. Requestdispatcher getrequestdispatcherstring path the same method belongs to both the servletrequest interface and the servletcontext interface.

Requestdispatcher is an interface that enables the servlet container to dispatch the request from a web application to another within the same context. This method forwards a request from a servlet to another resource servlet, jsp file or html file on the server. Servletconfig object will be available in init method of the servlet. String is that this method can take a relative path. Different servlets can live in different servletcontexts, but a servlet engine can group related servlets in the same servletcontext. 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. Using the requestdispatcher object with the include method we can include the contents of another servlet in the current servlet. Requestdispatcher interface is used to receive a client request and can do one of the following two things 1 it can forward client request to some other servlet, jsp or html file. To understand the difference between these two methods, lets take an example. A requestdispatcher object can forward a clients request to a resource or include the resource itself in the response back to the client. Understanding jsp line of code with getrequestdispatcher stack. The getrequestdispatcher method of servletrequest interface returns the object of.

The genericservlet class implements the servlet and servletconfig interface in from mca mca501 at maharishi markandeshwar university. Check whether servlet config is null or not by calling getservletconfig. Close springs web application context for the given servlet context. This method allows servlets to gain access to the context for various parts of the server, and as needed obtain requestdispatcher objects from the context. Now when u get the servletcontext reference, u can invoke the getcontext using the method getcontexturipath. Servlet learning notes servletconfig, servletcontext. There are three ways to obtain requestdispatcher object. Servletconfig object is used to pass information to a servlet during initialization by getting configuration information from web. I am sure the exception is caused by getservletcontext, since when i replace it by request, the exception disappears.

Introduction to resquest dispatcher in servlet studytonight. Another difference between the two is that path of the getrequestdispatcherstring path of the servletrequest interface cannot extend outside the current servlet context whereas getrequestdispatcherstring path of the servletcontext can use the getcontextstring uripath method to obtain requestdispatcher for resources in foreign contexts. The following are top voted examples for showing how to use javax. Servletconfig creates an object of servletcontext then used it in a servlet to deploy it on the server the same as in servletconfig, but it has one important feature that makes it more useful. Servletconfig is used to pass configuration information to servlet. The server can also store extra information here in the form of string, object pairs. This interface defines an object that receives request from the client and sends them to any resource which can be servlet,html or jsp. We are going to describe requestdispatcher in java. In lieu of this method, servlets can share information using the servletcontext class and can perform shared business logic by invoking methods on common nonservlet classes. An object implementing the requestdispatcher interface may be obtained via the following methods. The following are jave code examples for showing how to use getservletregistration of the javax. Difference between getrequestdispatcher method of the servletrequest interface and that of the servletcontext interface. String getservletname returns the name of this servlet instance.

A resource can be another servlet, or an html file, or a jsp file, etc. Returns the names of the contexts initialization parameters. Requestdispatcher is an interface that transfers the control from current web resource to another web resource such as a servlet, html, jsp on the server. What is the difference between the getrequestdispatcherstring path method of servletrequest interface and servletcontext interface. Get a requestdispatcher object use the forward method or include method of requestdispatcher.

We can maintain request scope by using servletrequest or. A servlet instance can determine its name using servletconfig. Returns the parameter value for the specified parameter name. First u get the reference to servlet context using getservletcontext method of genericservlet or using servletconfigs getservletcontext method. Let us see what api says about getrequestdispatcherstring path method. An attribute allows a servlet container to give the servlet additional information not already provided by this interface. New request is created for the destination resource. In this tutorial you will see that how getservletcontext method is used in servlet. The getservletcontext method and its uses with example. In this version, this method always returns null and remains only to preserve binary compatibility. The given path must be begin with, is interpreted relative to the server. When the web container initializes a servlet, it creates a servletconfig object for the servlet. Every servlet has its own servletconfig object and servlet.

This method will be permanently removed in a future version of the java servlet api. It gets the context from the servlets servletconfig object. The getrequestdispatcher methods sets the folloing request attributes while transfering. There is given some commonly used methods of servletcontext interface. In this example we are retrieving all the values from the web. Servlet interface cannot have a constructor that accepts a servletconfig parameter. The requestdispatcher interface provides the facility of dispatching the request to another resource it may be html, servlet or jsp. Defines a set of methods that a servlet uses to communicate with its servlet container, for example, to get the mime type of a file, dispatch requests, or write to a log file. This method was originally defined to retrieve a servlet from a servletcontext. The difference between this method and servletcontext. There are two methods defined in the requestdispatcher interface. Servlet specific information can be transferred to a servlet using a class implementing the servletconfig interface. In the servletconfig object, it encapsulates the relevant parameters needed to initialize the servlet program. For constructing a requestdispatcher object, you can use either the servletrequest.

In page x you have an include tag, this means that the control will be in the page x till it encounters include tag, after that the control will be transferred to page y. This interface is intended to wrap servlets, but a servlet container can create requestdispatcher objects to wrap any type of resources. What is the defferent between getnameddispatcher and. By using this object servlet can get its configuration information. It enables one servlet to do prelude processing of a request and another resource to create the response. The servletcontext object is contained within the servletconfig object.