public class UnavailableException extends ServletException
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.
| Constructor and Description |
|---|
UnavailableException(int seconds,
Servlet servlet,
String msg)
Deprecated.
As of Java Servlet API 2.2, use
UnavailableException(String, int) instead. |
UnavailableException(Servlet servlet,
String msg)
Deprecated.
As of Java Servlet API 2.2, use
UnavailableException(String) instead. |
UnavailableException(String msg)
Constructs a new exception with a descriptive message indicating that the
servlet is permanently unavailable.
|
UnavailableException(String msg,
int seconds)
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.
|
| Modifier and Type | Method and Description |
|---|---|
Servlet |
getServlet()
Deprecated.
As of Java Servlet API 2.2, with no replacement.
|
int |
getUnavailableSeconds()
Returns the number of seconds the servlet expects to be temporarily
unavailable.
|
boolean |
isPermanent()
Returns a
boolean indicating whether the servlet is
permanently unavailable. |
getRootCauseaddSuppressed, fillInStackTrace, getCause, getLocalizedMessage, getMessage, getStackTrace, getSuppressed, initCause, printStackTrace, printStackTrace, printStackTrace, setStackTrace, toStringpublic UnavailableException(Servlet servlet, String msg)
UnavailableException(String) instead.servlet - the Servlet instance that is unavailablemsg - a String specifying the descriptive messagepublic UnavailableException(int seconds,
Servlet servlet,
String msg)
UnavailableException(String, int) instead.seconds - an integer specifying the number of seconds the servlet
expects to be unavailable; if zero or negative, indicates that
the servlet can't make an estimateservlet - the Servlet that is unavailablemsg - a String specifying the descriptive message,
which can be written to a log file or displayed for the user.public UnavailableException(String msg)
msg - a String specifying the descriptive messagepublic UnavailableException(String msg, int seconds)
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.
msg - a String specifying the descriptive message,
which can be written to a log file or displayed for the user.seconds - an integer specifying the number of seconds the servlet
expects to be unavailable; if zero or negative, indicates that
the servlet can't make an estimatepublic boolean isPermanent()
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 is permanently unavailable;
false if the servlet is available or temporarily
unavailablepublic Servlet getServlet()
Servlet object that is throwing the
UnavailableExceptionpublic int getUnavailableSeconds()
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.
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