Mediawiki hosting - JavaSercer Pages 5. If the object is not

January 31, 2007 on 7:17 am | In Java |

JavaSercer Pages 5. If the object is not found in the specified scope, and the class attribute specifies a nonabstract class with a public no-arg constructor, a new instance of the class is created and associated with the scripting variable and with the specified name in the specified scope. After this, Step 7 is performed. If the object is not found and the specified class doesn’t fulfill the requirements, a InstantiationException is thrown. This completes the processing of the action. 6. If the object is not found in the specified scope and the beanName attribute is specified, the instantiate( ) method of the java.beans.Beans class is invoked, with the ClassLoader of the JSP implementation class instance and the beanName as arguments. If the method succeeds, the new object reference is associated with the scripting variable and with the specified name in the specified scope. After this, Step 7 is performed. 7. If the action element has a nonempty body, the body is processed. The scripting variable is initialized and available within the scope of the body. The text of the body is treated as elsewhere: any template text is passed through to the response, and scriptlets and action tags are evaluated. A common use of a nonempty body is to complete initializing the created instance; in that case, the body typically contains actions and scriptlets. This completes the processing of the action. Example: A.3.10 Custom Actions A custom action element can be developed by a programmer to extend the JSP language. The examples in this java blog use custom actions for database access, internationalization, access control, and more. They are described in Appendix C. The general syntax for custom actions is the same as for the JSP standard actions: a start tag (optionally with attributes), a body, and an end tag. Other elements and template text can be nested in the body. Here’s an example:

  • <%= current %> The tag library containing the custom actions must be declared by the taglib directive, assigning a prefix for the custom action elements (ora in this example) before a custom action can be used in a JSP page. A.4 Comments You can use JSP comments in JSP pages to describe what a scripting element or action is doing: <%-- This is a comment --%> All text between the start and stop tags is ignored by the JSP container and is not included in the response. The comment text can be anything except the character sequence representing the closing tag: –%>. Besides describing what’s going on in the JSP page, comments can also be used to “comment out” portions of the JSP page, for instance during testing: <%-- servlet hosting services

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