| java.lang.Object
 java.lang.Throwable
java.lang.Exception
javax.servlet.ServletException
javax.servlet.UnavailableException
| UnavailableException | | public class UnavailableException extends ServletException (Code) | | Defines an exception that a servlet or filter throws to indicate
that it is permanently or temporarily unavailable.
When a servlet or filter is permanently unavailable, something is wrong
with it, and it cannot handle
requests until some action is taken. For example, a servlet
might be configured incorrectly, or a filter's state may be corrupted.
The component should log both the error and the corrective action
that is needed.
A servlet or filter is temporarily unavailable if it cannot handle
requests momentarily due to some system-wide problem. For example,
a third-tier server might not be accessible, or there may be
insufficient memory or disk storage to handle requests. A system
administrator may need to take corrective action.
Servlet containers can safely treat both types of unavailable
exceptions in the same way. However, treating temporary unavailability
effectively makes the servlet container more robust. Specifically,
the servlet container might block requests to the servlet or filter for a period
of time suggested by the exception, rather than rejecting them until
the servlet container restarts.
author:
Various
version:
$Version$ |
| Method Summary | |
| public Servlet | getServlet()
| | public int | getUnavailableSeconds()
Returns the number of seconds the servlet expects to
be temporarily unavailable. | | public boolean | isPermanent()
Returns a boolean indicating
whether the servlet is permanently unavailable. |
| UnavailableException | | public UnavailableException(int seconds, Servlet servlet, String msg)(Code) | | UnavailableException.UnavailableException(String,int)
Parameters:
seconds - an integer specifying the number of secondsthe servlet expects to be unavailable; ifzero or negative, indicates that the servletcan't make an estimate
Parameters:
servlet - the Servlet that is unavailable
Parameters:
msg - a String specifying the descriptive message, which can be written to a log file or displayed for the user. |
| UnavailableException | | public UnavailableException(String msg)(Code) | | Constructs a new exception with a descriptive
message indicating that the servlet is permanently
unavailable.
Parameters:
msg - a String specifying thedescriptive message |
| UnavailableException | | public UnavailableException(String msg, int seconds)(Code) | | Constructs a new exception with a descriptive message
indicating that the servlet is temporarily unavailable
and giving an estimate of how long it will be unavailable.
In some cases, the servlet cannot make an estimate. For
example, the servlet might know that a server it needs is
not running, but not be able to report how long it will take
to be restored to functionality. This can be indicated with
a negative or zero value for the seconds argument.
Parameters:
msg - a String specifying thedescriptive message, which can be writtento a log file or displayed for the user.
Parameters:
seconds - an integer specifying the number of secondsthe servlet expects to be unavailable; ifzero or negative, indicates that the servletcan't make an estimate |
| getServlet | | public Servlet getServlet()(Code) | | the Servlet object that is throwing the UnavailableException |
| getUnavailableSeconds | | public int getUnavailableSeconds()(Code) | | Returns the number of seconds the servlet expects to
be temporarily unavailable.
If this method returns a negative number, the servlet
is permanently unavailable or cannot provide an estimate of
how long it will be unavailable. No effort is
made to correct for the time elapsed since the exception was
first reported.
an integer specifying the number of secondsthe servlet will be temporarily unavailable,or a negative number if the servlet is permanentlyunavailable or cannot make an estimate |
| isPermanent | | public boolean isPermanent()(Code) | | Returns a boolean indicating
whether the servlet is permanently unavailable.
If so, something is wrong with the servlet, and the
system administrator must take some corrective action.
true if the servlet ispermanently unavailable; falseif the servlet is available or temporarilyunavailable |
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