Jun 17, 2014 that is, the mango cost should be global. A servlet accesses these shared resource such as a requestdispatcher and application properties through the servletcontext object. The requestdispatcher is an interface that is used to chain and called one servlet from another or an html page from a servlet. Difference between servletconfig and servletcontext. This method can accept relative url as well as absolute url. Servletconfig is an interface that declares some methods to find out the namevalue parameter names, values, servlet name, servlet context. Servlet lifecycle methods are declared in the body of the servlet. Requstdispatcher can be get using getrequestdispacther method of servletrequest andor from the servletcontext.
If you know any servlet interview question that has not been included here, kindly post your question in the ask question section. An object of servletconfig is created by the web container for each servlet. Returns the parameter value for the specified parameter name. Servletconfig object is used to pass information to a servlet during initialization by getting configuration information from 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 servlet s class name. Servletconfig object of one servlet is abstract from servletconfig object of another servlet.
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. Actually the servletcontext name is quite confusing, it should change to appconfig or appcontext in the future release. How do you pass the data from one servlet to another servlet. That is, client calls one servlet say s1 but response goes from another servlet say s2. Using servletconfig interface servlet tutorial studytonight. What is the difference between servletcontext and servletconfig. Dec 07, 2015 servletconfig a servlet configuration object used by a servlet container to pass information to a servlet during initialization using init param. Inturn, servlet a can forward the client request to another servlet say, servlet b using requestdispatcher. So it is easier to manage the web application if any specific content is modified from. Difference between servletconfig and servletcontext in.
We are going to describe requestdispatcher in java. 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. This interface is intended to wrap servlets, but a servlet container can create requestdispatcher objects to wrap any type of resources. Can we use requestdispatcher from web application a to call web application b servlet. For the redirection of client request to another website. Requestdispatcher servlet api documentation apache tomcat.
If you want to add functionality at inittime, you should do it by overriding init. As shown in the figure 1 below, genericservlet implements the javax. How to forward from servlet to another servlet located in. This interface can also be used to include the content of another resource also. When you want paramters which cannot be hardcoded in your servlet you use servletconfig. 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. Which statement is true about include method of requestdispatcher interface. Genericservlet class implements the servlet and servletconfig interfaces, hence we can directly call the methods of servletconfig within this servlet. Hello rohit, to get the requestdispatcher you need to set the crosscontext to true. 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. Passing data from servlet to another servlet using requestdispatcher. Infact, requestdispatcher object can be obtained in another way also using javax. We should give request explicitly, in order to create servletconfig object for the first time.
In both the programs, getrequestdispatcherstring path of servletrequest is used to obtain an object of requestdispatcher. The servletcontext object is contained within the servletconfig object. Servlet sendredirect w3schools tutorialspoint w3adda. Java servletconfig tutorial passing initialization data. Servlet container creates servletconfig object for each servlet during initialization, to pass information to the servlet. Requestdispatcher is an interface and it is a part of the servlet api. Object of servletconfig will be created during initialization process of the servlet. All servlets instances running in the same context are part of the same web application and, therefore, share common resources. Some realtime scenarios to use requestdispatcher include method. Requestdispatcher methods with examples in servlet. Calling servlet from servlet request dispatcher method sendredirect method in servlet sharing data. Or simply to say, to put the output of one servlet into another. Servletconfig is an object containing some initial parameters or configuration information created by servlet container and passed to the servlet during initialization.
Servletconfig object will be available in init method of the servlet. Forwards a request from a servlet to another resource servlet, jsp file, or html file on the server. After obtaining a requestdispatcher, the servlet programmer forward a request to the target component or include content from it. Servletcontexts getcontext method servlets forum at. 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. There are two methods defined in the requestdispatcher interface.
There will be only one servletcontext object available accessed by all servlets. The same getrequestdispatcherstring path method exist in. Realtime examples on servletconfig vs servletcontext. The requestdispatcher class enables your servlet to call another servlet from inside another servlet. Correct understanding of what is servletcontext and servletconfig is very important for any j2ee application developer. Servletconfig interface for programmers convenience. There is a list of 30 servlet interview questions for beginners and professionals. You just need to pass servletmapping s urlpattern in the getrequestdispatcher. Example of servletconfig in java servlet, how to use. This method forwards a request from a servlet to another resource servlet, jsp file or html file on the server. Let say your servlet mapping is mymap for the mapout. Servletconfig is for a particular servlet, that means one should store servlet specific information in web. Difference between servletconfig and servletcontext in java. The word send redirect saying everything that this method is used to redirect the response to another resources such as jsp, servlet, html file.
But, the difference lies in the fact that information shared. That is here, client gets the response of both servlets. 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. We can pass the data from one servlet to another using requestdispatcher object. We have seen two programs with include and forward methods of requestdispatcher. String uripath 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 requestdispatcher interface provides the option of dispatching the clients request to another web resource, which could be an html page, another servlet.
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. Requestdispatcher from servletrequest vs servletcontext. It forwards the request from one servlet to another resource such as servlet, jsp. The place to put the cost of mango is in which exists outside any servlet tag. The core advantage of servletconfig is that you dont need to edit the servlet file if information is modified from the web.
Many servlet s developers are confuse about the different between servletconfig and servletcontext. The requestdispatcher interface defines an object that receives the request from client and dispatches it to the resource such as servlet, jsp, html file. Difference between servletconfig and servletcontext javapapers. They run in servlet containers such as tomcat or jetty. Apart from that difference between servletcontext and servletconfig are a popular servlet jsp interview questions and. Using this configuration file with the requestdispatcher object with the forward method we can forward the contents of one servlet to another servlet. Many servlets developers are confuse about the different between servletconfig and servletcontext. Servlet requestdispatcher forward and include 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. Difference between servletcontext and servletconfig. Includes the content of a resource servlet, jsp page, html file in the response. Forwards a request from a servlet to another resource servlet, jsp file, or html file. This tutorial explains the requestdispatcher class in java servlets which can be used to include the response of another servlet into the. It works at client side because it uses the url bar of the browser to make another request. Then how the first servlet called by the client can send forward the request to another servlet. Called by the servlet container to allow the servlet to respond to a request. Servletcontext requestdispatcher getrequestdispatcherstring servletpath. It enables one servlet to do prelude processing of a request and another resource. I read the number of mangoes from the client html file. But it knows that another servlet exists which can do the job of the client. For sending any existing html form on the server to client. The full path to import and access all the methods provided by servletcontext is javax.
Suppose i would like to know the amount payable for the number of mangoes purchased. Servlet container uses the servlet configuration object to pass information to a servlet on initialization. It forwards the request from one servlet to another resource such as. The advantage of servletconfig is that it eliminates the need to edit the servlet file if the information is modified from the web. To place include the response content ouput of one servlet into another servlet s response. It is once created for every servlet designed in the application at container startup. The requestdispatcher will find the current request and response while chaining calls. 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. Requestdispatcher is used to dispatch request to the resource run in same web applications, and sendredirect can be used to redirect client. Each servlet comes with a separate servletconfig object. This object can be used to get configuration information from web. Set to true if you want calls within this application to servletcontext. Difference between forward and sendredirect method. What are the differences between servletcontext vs.
The given path must be begin with, is interpreted relative to the servers. The servletcontext is for the whole webapp but the servletconfig is for one particular servlet. This object can be used to get configuration information such as parameter name and values from deployment descriptor fileweb. May 04, 2012 each servlet instance is running in one of these contexts. If the configuration information is modified from the web. Pass your comments and suggestions on this tutorial servletconfig vs servletcontext. As long as a servlet is executing, servletconfig object will be available, it will be destroyed once the servlet execution is completed.
Servlet collaboration in java using requestdispatcher and. 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. 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. Servletcontext and servletconfig these two are important interface of servlet api which is used by java j2ee programmer during web application development. Servlets and jsp pages also may be given names via server administration or via a web application deployment descriptor. For understanding, this is similar to a constructor in a java class. 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. The requestdispatcher interface provides the facility of dispatching the request to another resource it may be html, servlet or jsp. Modernday java web development uses frameworks that are built on top of servlets. 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 returns null if the servletcontext cannot return a requestdispatcher for any reason. But the servlet cannot honour the request because it is incapable. Returns a requestdispatcher object that acts as a wrapper for the named servlet. Difference between servletconfig and servletcontext in jsp.
All servlets must implement this servlet interface. Can we use requestdispatcher to access another web. Servlet requestdispatcher w3schools tutorialspoint w3adda. Passing data from servlet to another servlet using. These two methods are commonly used to send the request to another resources but there are some difference between both method. As it is outside any servlet tag, every servlet under execution can access. Requestdispatcher is an interface which has two important abstract methods defined. Using requestdispatcher to forward a request we are creating a servlet by extending the genericservlet abstract class. Introduction to servletconfig interface when the web container initializes a servlet, it creates a servletconfig object for the servlet.
What if we override the initservletconfig and dont call. You need to understand servlet thoroughly before you could proceed to other. A servlet instance can determine its name using servletconfig. Dec 14, 20 in this tutorial you will learn how to use forward method of requestdispatcher in servlet forward method of requestdispatcher forwards the request made by the client by the the resource any of them servlet, jsp, html, etc.
Servlet requestdispatcher w3schools tutorialspoint. Servlet interface is the heart of the servlet architecture. 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. Servletcontext servlet and javaserver pages api documentation. 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. Requestdispatcher interface in servlet java tutorial. For the redirection of errors to another resources such as servlet, jsp or html file. This interface is intended to wrap servlets, but a servlet container can create requestdispatcher objects to wrap any type of resource. String getservletname returns the name of this servlet instance. These two interfaces include the methods responsible for achieving the objective of sharing information between servlets. The servlet container creates the requestdispatcher object, which is used as a wrapper.
Requestdispatcher, getcontextstring, servletconfig. This config object is public to a particular servlet only. The parameter you give to the getrequestdispatcher method does not refer to the servlet class name, but to its mapping. That is, you can pass initialization parameters to the servlet using the web. A web container is responsible for creating servletconfig object for each servlet the servletconfig object passes the information to a servlet during initialization. Forward to a servlet from another servlet or from a filter stack. 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. This interface is intended to wrap servlets, but a servlet container can create requestdispatcher objects to wrap any type of.
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