There are two methods defined in the requestdispatcher interface. The requestdispatcher will find the current request and response while chaining calls. We have seen two programs with include and forward methods of requestdispatcher. Difference between servletconfig and servletcontext. This interface can also be used to include the content of another resource also. How to forward from servlet to another servlet located in. Requestdispatcher interface in servlet java tutorial. It is used by a servlet container to pass information to a servlet during initialization. This interface is intended to wrap servlets, but a servlet container can create requestdispatcher objects to wrap any type of resource. To place include the response content ouput of one servlet into another servlet s response.
The given path must be begin with, is interpreted relative to the servers document root and is matched against the context roots of other web. This object can be used to get configuration information from web. The core advantage of servletconfig is that you dont need to edit the servlet file if information is modified from the web. Servletconfig object is used to pass information to a servlet during initialization by getting configuration information from web. Java servletconfig tutorial passing initialization data. Servlet sendredirect w3schools tutorialspoint w3adda. This config object is public to a particular servlet only.
This method returns null if the servletcontext cannot return a requestdispatcher for any reason. But, the difference lies in the fact that information shared. This tutorial explains the requestdispatcher class in java servlets which can be used to include the response of another servlet into the. That is, client calls one servlet say s1 but response goes from another servlet say s2. Servlet lifecycle methods are declared in the body of the servlet.
Servletconfig interface for programmers convenience. Servletconfig is an object containing some initial parameters or configuration information created by servlet container and passed to the servlet during initialization. Servlet container creates servletconfig object for each servlet during initialization, to pass information to the servlet. But it knows that another servlet exists which can do the job of the client. Hello rohit, to get the requestdispatcher you need to set the crosscontext to true. Using requestdispatcher to forward a request we are creating a servlet by extending the genericservlet abstract class. Requestdispatcher, getcontextstring, servletconfig. Servlets requestdispatcher and page redirection tutorial to learn servlets requestdispatcher and page redirection in simple, easy and step by step way with syntax, examples and notes. How do you pass the data from one servlet to another servlet. You just need to pass servletmapping s urlpattern in the getrequestdispatcher. Using this configuration file with the requestdispatcher object with the include method we can include the contents of another servlet in the current servlet. This method can accept relative url as well as absolute url. This interface is intended to wrap servlets, but a servlet container can create requestdispatcher objects to wrap any type of. Returns a requestdispatcher object that acts as a wrapper for the named servlet.
Suppose i would like to know the amount payable for the number of mangoes purchased. We should give request explicitly, in order to create servletconfig object for the first time. Using servletconfig interface servlet tutorial studytonight. Set to true if you want calls within this application to servletcontext. Passing data from servlet to another servlet using requestdispatcher. Infact, requestdispatcher object can be obtained in another way also using javax. As it is outside any servlet tag, every servlet under execution can access. That is, you can pass initialization parameters to the servlet using the web. After obtaining a requestdispatcher, the servlet programmer forward a request to the target component or include content from it. Called by the servlet container to allow the servlet to respond to a request. It enables one servlet to do prelude processing of a request and another resource. When you want paramters which cannot be hardcoded in your servlet you use servletconfig. It is once created for every servlet designed in the application at container startup. You need to understand servlet thoroughly before you could proceed to other.
The servletcontext is for the whole webapp but the servletconfig is for one particular servlet. Difference between servletcontext and servletconfig. 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 servlet s class name. Dec 07, 2015 servletconfig a servlet configuration object used by a servlet container to pass information to a servlet during initialization using init param. Some realtime scenarios to use requestdispatcher include method. It forwards the request from one servlet to another resource such as servlet, jsp. String getservletname returns the name of this servlet instance. Forward to a servlet from another servlet or from a filter stack. 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.
The word send redirect saying everything that this method is used to redirect the response to another resources such as jsp, servlet, html file. Servletcontext and servletconfig these two are important interface of servlet api which is used by java j2ee programmer during web application development. If the configuration information is modified from the web. Servletcontexts getcontext method servlets forum at. A servlet accesses these shared resource such as a requestdispatcher and application properties through the servletcontext object. Difference between servletconfig and servletcontext javapapers. For the redirection of errors to another resources such as servlet, jsp or html file. The servlet container creates the requestdispatcher object, which is used as a wrapper. Realtime examples on servletconfig vs servletcontext.
Because when we call a servlet from within another servlet using the forward servletresponse, servletrequest method, we also pass the servletrequest and servletresponse objects to the other servlet method and the response object is destroyed once the another servlet commits the output. Requestdispatcher is used to dispatch request to the resource run in same web applications, and sendredirect can be used to redirect client. For the redirection of client request to another website. The requestdispatcher class enables your servlet to call another servlet from inside another servlet. An object of servletconfig is created by the web container for each servlet. Servletconfig is for a particular servlet, that means one should store servlet specific information in web. For understanding, this is similar to a constructor in a java class. Servlet requestdispatcher w3schools tutorialspoint. This interface is intended to wrap servlets, but a servlet container can create requestdispatcher objects to wrap any type of resources. Servlets and jsp pages also may be given names via server administration or via a web application deployment descriptor.
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. There will be only one servletcontext object available accessed by all servlets. These two methods are commonly used to send the request to another resources but there are some difference between both method. But the servlet cannot honour the request because it is incapable. We can pass the data from one servlet to another using requestdispatcher object. It forwards the request from one servlet to another resource such as. Pass your comments and suggestions on this tutorial servletconfig vs servletcontext.
Requestdispatcher is an interface and it is a part of the servlet api. The requestdispatcher interface provides the option of dispatching the clients request to another web resource, which could be an html page, another servlet, jsp etc. But, the difference lies in the fact that information shared by servletconfig is for a specific servlet, while information shared by servletcontext is available for all servlets in the web application. Calling servlet from servlet request dispatcher method sendredirect method in servlet sharing data. Example of servletconfig in java servlet, how to use. Includes the content of a resource servlet, jsp page, html file in the response. Difference between servletconfig and servletcontext in jsp. What if we override the initservletconfig and dont call. Or simply to say, to put the output of one servlet into another. Servlet requestdispatcher forward and include method. These two interfaces include the methods responsible for achieving the objective of sharing information between servlets. Requstdispatcher can be get using getrequestdispacther method of servletrequest andor from the servletcontext.
As long as a servlet is executing, servletconfig object will be available, it will be destroyed once the servlet execution is completed. The parameter you give to the getrequestdispatcher method does not refer to the servlet class name, but to its mapping. Returns a servletcontext object that corresponds to a specified url on the server 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. The place to put the cost of mango is in which exists outside any servlet tag. Let say your servlet mapping is mymap for the mapout. Because when we call a servlet from within another servlet using the forwardservletresponse, servletrequest method, we also pass the servletrequest and servletresponse objects to the other servlet method and the response object is destroyed once the another servlet commits the output. All servlets must implement this servlet interface. Servlet interface is the heart of the servlet architecture.
Requestdispatcher servlet api documentation apache tomcat. Servletconfig object will be available in init method of the servlet. Inturn, servlet a can forward the client request to another servlet say, servlet b using requestdispatcher. Servletconfig and servletcontext, both are objects created at the time of servlet initialization and used to provide some initial parameters or configuration information to the servlet.
Modernday java web development uses frameworks that are built on top of servlets. The requestdispatcher interface defines an object that receives the request from client and dispatches it to the resource such as servlet, jsp, html file. Correct understanding of what is servletcontext and servletconfig is very important for any j2ee application developer. As shown in the figure 1 below, genericservlet implements the javax. Jun 17, 2014 that is, the mango cost should be global. Can we use requestdispatcher from web application a to call web application b servlet. What are the differences between servletcontext vs. Servletcontext servlet and javaserver pages api documentation. This object can be used to get configuration information such as parameter name and values from deployment descriptor fileweb.
Difference between servletconfig and servletcontext in java. May 04, 2012 each servlet instance is running in one of these contexts. Each servlet comes with a separate servletconfig object. They run in servlet containers such as tomcat or jetty. The servletcontext object is contained within the servletconfig object. So it is easier to manage the web application if any specific content is modified from. It works at client side because it uses the url bar of the browser to make another request.
The given path must be begin with, is interpreted relative to the servers. Requestdispatcher from servletrequest vs servletcontext. You just need to pass servlet mapping s urlpattern in the getrequestdispatcher let say your servlet mapping is mymap for the mapout servlet in the web. There is a list of 30 servlet interview questions for beginners and professionals. If you know any servlet interview question that has not been included here, kindly post your question in the ask question section. 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. Difference between forward and sendredirect method.
Servlet requestdispatcher interface this interface defines an object that receives request from the client and sends them to any resource which can be servlet,html or jsp. Servletconfig is an interface that declares some methods to find out the namevalue parameter names, values, servlet name, servlet context. Genericservlet class implements the servlet and servletconfig interfaces, hence we can directly call the methods of servletconfig within this servlet. A servlet instance can determine its name using servletconfig.
There are two methods in servlet to dispatch user request to other web resources such as jsp, html or another servlet in the same or different web applications. A web container is responsible for creating servletconfig object for each servlet the servletconfig object passes the information to a servlet during initialization. Object of servletconfig will be created during initialization process of the servlet. Passing data from servlet to another servlet using. I read the number of mangoes from the client html file. Returns the parameter value for the specified parameter name. The requestdispatcher interface provides the facility of dispatching the request to another resource it may be html, servlet or jsp. This method forwards a request from a servlet to another resource servlet, jsp file or html file on the server. Which statement is true about include method of requestdispatcher interface. Apart from that difference between servletcontext and servletconfig are a popular servlet jsp interview questions and.
Servlet requestdispatcher w3schools tutorialspoint w3adda. If you want to add functionality at inittime, you should do it by overriding init. Forwards a request from a servlet to another resource servlet, jsp file, or html file on the server. For sending any existing html form on the server to client. Many servlet s developers are confuse about the different between servletconfig and servletcontext. Forwards a request from a servlet to another resource servlet, jsp file, or html file. The requestdispatcher is an interface that is used to chain and called one servlet from another or an html page from a servlet. Requestdispatcher methods with examples in servlet. The requestdispatcher interface provides the option of dispatching the clients request to another web resource, which could be an html page, another servlet. All servlets instances running in the same context are part of the same web application and, therefore, share common resources.
We are going to describe requestdispatcher in java. In both the programs, getrequestdispatcherstring path of servletrequest is used to obtain an object of requestdispatcher. Servletcontext requestdispatcher getrequestdispatcherstring servletpath. Servlet collaboration in java using requestdispatcher and. What is the difference between servletcontext and servletconfig. The advantage of servletconfig is that it eliminates the need to edit the servlet file if the information is modified from the web. Or to put it another way, servlet a can process the client request halfway and pass the halfprocessed data to servlet b for further processing and sending to client the response.
The same getrequestdispatcherstring path method exist in. Servlet container uses the servlet configuration object to pass information to a servlet on initialization. That is here, client gets the response of both servlets. Can we use requestdispatcher to access another web. Requestdispatcher is an interface which has two important abstract methods defined. Many servlets developers are confuse about the different between servletconfig and servletcontext. Actually the servletcontext name is quite confusing, it should change to appconfig or appcontext in the future release. Difference between servletconfig and servletcontext in. Servletconfig object of one servlet is abstract from servletconfig object of another servlet. Then how the first servlet called by the client can send forward the request to another servlet. Introduction to servletconfig interface when the web container initializes a servlet, it creates a servletconfig object for the servlet.
1022 1534 649 1082 280 1512 434 1067 362 758 118 1444 1526 370 181 9 697 725 255 870 244 454 566 314 466 1085 297 828 1434 1142 1053 154 59 57 674 557 355