This process method then looks into the strutsconfig. This process method then looks into the struts config. Continued from page 1 if the testservlet which is mapped to test is hit with no parameters, we see the following. They can be used in the action class to store the information.
It forwards the request from one servlet to another resource such as. The requestdispatcher interface defines an object that receives the request from client and dispatches it to the resource such as servlet, jsp, html file. The servletresponse object has its path elements, and parameters remain unchanged from the callers. Actionservlet represents the controller in the modelviewcontroller mvc design pattern for web applications that is commonly known as model 2. The requestdispatcher object has two methods, include and forward. Sep 09, 2006 but in current version of struts, they have replaced requestprocessor with requestdispatcher. Struts uses the requestprocessor class to perform the processing for all requests received by the actionservlet. In essence, this method enables programmatic serverside includes. Actionservlet which intercept the request and calls requestprocessors process method for further processing requestprocessor read xml file, find the appropriate handler and handles request. The requestprocessor class is the actual place where the request processing takes place in a struts controller environment. You can customize the request processing behavior by subclassing this class and overriding the methods whose behavior you are interested in changing.
Any struts web application contain the actionservlet configuration in web. Nullpointerexception with requestdispatcher oracle community. What is the request processor in struts and how it works. The requestprocessor class is the actual place where the request processing takes place in a struts controller environment when the request object first reaches the actionservlet class then it invokes the process method of the underlying requestprocessor class this process method then looks into the strutsconfig. This is what javadoc says about requestdispatcher include. A requestdispatcher object can be used to forward a request to the resource or to include the resource in a response. Requestprocessor checks whether any tag is available in strutsconfig.
The requestprocessor class takes each request and breaks its processing down into several small tasks. In other words, this method allows serverside to include the response of destination program to source program. This can be done by using requestdispatcher interface. When the request object first reaches the actionservlet class then it invokes the process method of the underlying requestprocessor class. The controller is responsible for intercepting and translating user input into actions to be performed by the model.
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. It is used to include the content of another resource also. What is the difference between requestdispatchers forward. Mar 28, 2015 you have to do two things to implement custom request processor in struts. Dispatcher a utility class the actual dispatcher delegates most of its tasks to. Apr 08, 2008 requestdispatcher object, difference between include and forward method. Each websphere commerce web module has its own struts configurations, defining base actions and globalforwards that can be difficult to debug runtime problems. A requestdispatcher object can forward a clients request to a resource or include the resource itself in the response back to the client. If actioninclude is appended as a url parameter, we see that the requestdispatcher object includes the contents of index. Struts flow start with actionservlet then call to process method of requestprocessor. Troubleshooting websphere commerce struts configurations. Requestdispatcher include method comes to the rescue. The response will not be sent back to the client and the web container for example, tomcat internally redirects the request to the other jspservlet.
Requestdispatcher the requestdispacher interface provides the facility of dispatching the request to another resource like html, servlet or jsp. Migrating from struts 1 to struts 2 raible designs. This approach lets you customize the way each individual part of the request is. Filterdispatcher is used in the early struts2 development, and its deprecated since struts 2. Using the request dispatcher function, an attribute msg is sent from process. Includes the content of a resource servlet, jsp page, html file in the response. The controller is responsible for selecting the next view based on user input and the outcome of model operations. Nullpointerexception with requestdispatcher 800345 jul 8, 2008 11. What is the request processor in struts and how it. In fact, the struts controller retains its thread until the action is done with its processing and then it the controller decides which view jsp to forward to. In this example we have used jsp requestdispatcher.
Let us see a practical example of requestdispatcher include method. Struts tutorial code examples struts flowhow struts works. The included servlet cannot change the response status code or set headers. These examples are extracted from open source projects. What is the use of requestprocessor, if we are having. It provides an interface through which the servlets can collaborate with each other. Here servletresponse object are passed as the argument of include method. Request processor define some command classes which belong to either the org. Requestdispatcher is an interface, implementation of which defines an object which can dispatch request to any resources. Dec 07, 2014 java requestdispatcher in servlet example instance of java requestdispatcher in servlet instanceofjava this is the java programming blog on oops concepts, servlets jsp freshers and 1, 2,3 years expirieance java interview questions on java with explanation for interview examination. We are going to discuss about requestdispatcher in jsp. Actionservlet treats all requests made to your struts application and delegates the heavy lifting stuff of handling the request to a requestprocessor object.
C in globalforwards section you can map a page on your webapp to a name. 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. You have to do two things to implement custom request processor in struts. The forward method of requestdispatcher will forward the servletrequest and servletresponse that it is passed to the path that was specified in getrequestdispatcherstring path. Dec 11, 20 requestdispatcher include method comes to the rescue. Load actionservlet using loadonstartup and do the following tasks. Hi manoj, you have mentioned one way of creating your own requestprocessor, but to locate services you should look at moduleconfig in detail. Each instance of the primary dispatcher holds an instance of this dispatcher to be shared for all requests. It recieves the request from the client and makes decision where to send the request for further processing based on the. Moduleconfig uses digesters to create java representation of struts. B in formbeans section, you can map your actionform subclass to a name. Requestdispatcher interface is implemented by servlet container to dispatch or to pass the request to a web resource such as servlet, html page or jsp page.
All interceptors are classes, which implements interceptor interface, so we must override all methods in the interceptor interface. Interview questions struts interview questions question. 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. The first task is to add to the web application the. Java differecne between requestprocessor and requestdispatcher. To dispatch the request from servlet or jsp to web resource using requestdispatcher we need to perform following steps. As you can see, the request dispatcher results are appended to the previous output results generated by testservlet. If matching then it will take the type attribute value and load that class. Until now, this tutorial is not related at all with struts 2. It is designed as a dropin replacement of the struts 1. The following are top voted examples for showing how to use org. A resource can be another servlet, or an html file, or a jsp file, etc. The following are top voted examples for showing how to use javax.
What is the use of requestprocessor, if we are having actionservlet in struts answer sk niloufer by default struts framework provides applicationcontroller design pattern in the form of requestprocessor whereas actionservlet is a replacement of frontcontroller design. The requestdispatcher interface provides the facility of dispatching the request to another resource it may be html, servlet or jsp. Returns a requestdispatcher object that acts as a wrapper for the resource located at the given path. The response will not be sent back to the client and so the client will not know about this change of resource on the server. Requestprocessor contains the processing logic that the struts controller servlet performs as it receives each servlet request from the container. There are two methods defined in the requestdispatcher interface. What is the difference between requestprocessor and. This interface can also be used to include the content of another resource also. This method of requestdispatcher interface includes the content of web resource servlets, jsp and html file in the response.
This interface is intended to wrap servlets, but a servlet container can create requestdispatcher objects to wrap any type of resource. The requestdispatcher class enables your servlet to call another servlet from inside another servlet. The actionservlet and requestdispatcher are main players in the struts framework. Struts does not use requestdispatcher to forward control to actions. What is the use of requestprocessor, if we are having actionservlet in struts answer sk niloufer by default struts framework provides applicationcontroller design pattern in the form of requestprocessor whereas actionservlet is a replacement of frontcontroller design pattern implementation. There are 4 aware interfaces in struts2, sessionaware, servletrequestaware, servletresponseaware and servletcontextaware. Requestprocessor checks whether any tag is available in struts config. This nomenclature originated with a description in the javaserverpages specification, version 0. Requestdispatcher object, difference between include and forward method.
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