Page context and exception implicit object
- 1. page Context and Exception implicit object Prof. Neeraj Bhargava Kapil Chauhan Department of Computer Science School of Engineering & Systems Sciences MDS University, Ajmer
- 2. page Context implicit object In JSP, pageContext is an implicit object of type PageContext class. The pageContext object can be used to set,get or remove attribute from one of the following scopes: page request session application
- 3. page implicit object: In JSP, page is an implicit object of type Object class. This object is assigned to the reference of auto generated servlet class. It is written as: Object page=this; For using this object it must be cast to Servlet type.
- 4. Cont.. For example: <% (HttpServlet)page.log("message"); %> Since, it is of type Object it is less used because you can use this object directly in jsp. For example: <% this.log("message"); %>
- 5. Exception implicit object In JSP, exception is an implicit object of type java.lang.Throwable class. This object can be used to print the exception. But it can only be used in error pages.
- 6. Example of exception implicit object: error.jsp <%@ page isErrorPage="true" %> <html> <body> Sorry following exception occured:<%= exception %> </body> </html>
- 7. index.jsp <form action="process.jsp"> No1:<input type="text" name="n1" /><br/><br/> No1:<input type="text" name="n2" /><br/><br/> <input type="submit" value="divide"/> </form>
- 8. process.jsp <%@ page errorPage="error.jsp" %> <% String num1=request.getParameter("n1"); String num2=request.getParameter("n2"); int a=Integer.parseInt(num1); int b=Integer.parseInt(num2); int c=a/b; out.print("division of numbers is: "+c); %>
- 9. error.jsp <%@ page isErrorPage="true" %> <h3>Sorry an exception occured!</h3> Exception is: <%= exception %>
- 10. Assignment Explain page Context and Exception implicit object with suitable example.