Java Servlet Technology in Java Generate USS Code 39 in Java Java Servlet Technology

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10 Java Servlet Technology using jdk todevelop code 39 extended on web,windows application Microsoft Office Excel Website Filtering Requests and Responses FIGURE 10 1 Filter-to-Servlet Mapping F1 F2 Recall that a f barcode 39 for Java ilter chain is one of the objects passed to the doFilter method of a filter. This chain is formed indirectly by means of filter mappings. The order of the filters in the chain is the same as the order in which filter mappings appear in the web application deployment descriptor.

When a filter is mapped to servlet S1, the web container invokes the doFilter method of F1. The doFilter method of each filter in S1 s filter chain is invoked by the preceding filter in the chain by means of the chain.doFilter method.

Because S1 s filter chain contains filters F1 and F3, F1 s call to chain.doFilter invokes the doFilter method of filter F3. When F3 s doFilter method completes, control returns to F1 s doFilter method.

. To Specify Filter Mappings Using NetBeans IDE 1 2 3 4 5 6 7. Expand the appl ication s project node in the Project pane. Expand the Web Pages and WEB-INF nodes under the project node. Double-click web.

xml. Click Filters at the top of the editor pane. Expand the Servlet Filters node in the editor pane.

Click Add Filter Element to map the filter to a web resource by name or by URL pattern. In the Add Servlet Filter dialog, enter the name of the filter in the Filter Name field..

The Java EE 6 Tutorial: Basic Concepts Invoking Other Web Resources Click Browse to Code 39 Extended for Java locate the servlet class to which the filter applies. You can include wildcard characters so that you can apply the filter to more than one servlet. Click OK.

To constrain how the filter is applied to requests, follow these steps. a. Expand the Filter Mappings node.

b. Select the filter from the list of filters. c.

Click Add. d. In the Add Filter Mapping dialog, select one of the following dispatcher types:.

9 10. REQUEST: Only w swing Code 3 of 9 hen the request comes directly from the client ASYNC: Only when the asynchronous request comes from the client FORWARD: Only when the request has been forwarded to a component (see Transferring Control to Another Web Component on page 192) INCLUDE: Only when the request is being processed by a component that has been included (see Including Other Resources in the Response on page 192) ERROR: Only when the request is being processed with the error page mechanism (see Handling Servlet Errors on page 182). You can direct the filter to be applied to any combination of the preceding situations by selecting multiple dispatcher types. If no types are specified, the default option is REQUEST..

Invoking Other Web Resources Web components can invoke other web resources both indirectly and directly. A web component indirectly invokes another web resource by embedding a URL that points to another web component in content returned to a client. While it is executing, a web component directly invokes another resource by either including the content of another resource or forwarding a request to another resource.

To invoke a resource available on the server that is running a web component, you must first obtain a RequestDispatcher object by using the getRequestDispatcher("URL") method. You can get a RequestDispatcher object from either a request or the web context; however, the two methods have slightly different behavior. The method takes the path to the requested resource as an argument.

A request can take a relative path (that is, one that does not begin with a /),. 10 Java Servlet Technology Invoking Other Web Resources but the web con swing 3 of 9 text requires an absolute path. If the resource is not available or if the server has not implemented a RequestDispatcher object for that type of resource, getRequestDispatcher will return null. Your servlet should be prepared to deal with this condition.

. Including Other Resources in the Response It is often use javabean bar code 39 ful to include another web resource, such as banner content or copyright information) in the response returned from a web component. To include another resource, invoke the include method of a RequestDispatcher object:. include(request, response);. If the resource barcode 3 of 9 for Java is static, the include method enables programmatic server-side includes. If the resource is a web component, the effect of the method is to send the request to the included web component, execute the web component, and then include the result of the execution in the response from the containing servlet. An included web component has access to the request object but is limited in what it can do with the response object.

. It can write to the body of the response and commit a response. It cannot set headers or call any method, such as setCookie, that affects the headers of the response..

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