JSP: The Complete Reference 2 Evolution of the Web Application 5. 3 Overview of the Hypertext Transfer Protocol (HTTP) JSP complete lamwordgafiri.tk - Ebook download as PDF File .pdf), Text File .txt) or read book 2 and and 1. respectively.2 and JSP lamwordgafiri.tk2 specifications We want to thank the community that implemented the reference implementation, and .. files that contain complete JSP pages, or included segments of pages.
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But the concept of the JSP scopes may be new. These scopes define the order in which variable names are resolved, the lifetime of the variable, and its purview.
The scopes, in their default search order, are: page, request, session and application. In Java code, these scoped variables are created by the setAttribute method of their respective Java classes.
Lifetime of the application context. Scoped variables can be created in many places, but a very common scenario is for the page controller servlet to create scoped variables in request scope, then forward to a JSP page in order to display that data. For example: This statement creates a request-scoped variable named greeting with the string value Hi there!. Now let's see how we can use that variable in a JSP.
Application scope is a very handy place to store information that needs to be made available to all resources within a web application. It's easy to establish such data whenever a web application starts up by doing so in context listener. A context listener is simply a Java class that implements the javax. ServletContextListener interface, and is declared as a listener in the deployment descriptor web. Methods in such a class are invoked whenever a web application is put into and taken out of service, making it an ideal choice for application setup and tear down.
And best of all, any scoped variables placed in application scope are available to any EL expression in any JSP in the application! Section 5 Referencing Simple Values The example code in the previous section created a scoped variable named greeting that contains a simple text value.
Regardless of what kind of value a scoped variable contains, it can be referenced in an EL expression simply by naming it. Scoped variables can be referenced anywhere in an EL expression. Let's say that the scoped variables a and b contain numeric values. Regardless of what type of values are referenced, the final evaluated result is always converted to its string equivalent before being emitted.
So if the result is a Java object whose class has no explicit toString method defined, you might end with goop like the following in the output: org. MyBean afd This can be rectified by making sure that the class in this case, MyBean has an appropriate toString method defined. Section 6 Grabbing JavaBean Properties While strings and numbers are useful for representing scalar values, more frequently, complex objects in the form of JavaBeans are what we have to deal with, so the EL is specifically designed to make it easy to access the properties of JavaBeans.
Although static resources may be included, it is not preferred as each request requires inclusion. JComponent is a subclass of Container.
It contains other Components and JComponents. How can a thread safe JSP page be implemented? It can be done by having them implemented by the SingleThreadModel Interface. How can the output of JSP or servlet page be prevented from being cached by the browser?
How to restrict page errors display in a JSP page? What are JSP Actions? Omit the tag if you do not want to require re-authentication. The default value is false.
Note: Because 2. SendRedirect method redirects using a relative or absolute URL. The default behavior is to convert the URL to a non-relative link.
Note: User readable data used in a redirect. The default value is false does not generate a directory.
Values are true or false. FileServlet is sorted. The default sort-by value is NAME. The value -1 means never check the servlets. This is the default value in a production environment. The value 0 means always check the servlets. The value 1 means check the servlets every second.
This is the default value in a development environment. A value specified in the console will always take precedence over a manually specified value.
This parameter identifies how often WebLogic Server checks whether a resource has been modified and if so, it reloads it. The value -1 means never reload.