Java Servlet Annotation
1.) The javax.servlet.annotation package contains a number of annotations that allow users to use annotations to declare servlets, filters, listeners and specify the metadata for the declared component.
2.)Servlet API 3.0 introduces a new package javax. servlet.annotation.
3.) Servlet API 3.0 provides annotation types used to annotating a servlet class.
4.) Annotation in Servlet API 3.0 replace xml configuration – web deployment descriptor file (web.xml) for servlet declaration and Servlet mapping.
5.) Servlet API 3.0 Annotation Types:
i.) @HandlesTypes
Description : Annotation type is used to declare the class types that a ServletContainerInitializer can handle. It has one attribute, value, that is used to declare the class types. For example, the following ServletContainerInitializer is annotated with @HandleTypes that declares that the initializer can handle UsefulServlet.
ii.) @HttpConstraint
Description : This annotation is used within the ServletSecurity annotation to represent the security constraints to be applied to all HTTP protocol methods for which a corresponding HttpMethodConstraint element does NOT occur within the ServletSecurity annotation.
iii.) @HttpMethodConstraint
Description : This annotation is used within the ServletSecurity annotation to represent security constraints on specific HTTP protocol messages.
iv.) @MultipartConfig
Description : Annotation that may be specified on a Servlet class, indicating that instances of the Servlet expect requests that conform to the multipart/form-data MIME type.Servlets annotated with MultipartConfig may retrieve the Part components of a given multipart/form-data request by calling getPart or getParts.
v.) @ServletSecurity
Description : This annotation is used on a Servlet implementation class to specify security constraints to be enforced by a Servlet container on HTTP protocol messages. The Servlet container will enforce these constraints on the url-patterns mapped to the servlets mapped to the annotated class.
vi.)@WebFilter
Description : This annotation is processed by the container at deployment time, and the corresponding filter applied to the specified URL patterns, servlets, and dispatcher types.
vii.) @WebInitParam
Description : This annotation is used on a Servlet or Filter implementation class to specify an initialization parameter.
viii.) @WebListener
Description This annotation is used to declare a WebListener. Any class annotated with WebListener must implement one or more of the ServletContextListener, ServletContextAttributeListener,ServletRequestListener, ServletRequestAttributeListener, HttpSessionListener, or HttpSessionAttributeListener interfaces.
x.) @WebServlet
Description : This annotation is processed by the container at deployment time, and the corresponding servlet made available at the specified URL patterns.
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