Question

I am attempting to set-up a scheme for uniformly handling exceptions in Spring. As such, I need a way to pass context information into an @ExceptionHandler-annotated method, for example consider the following:

@ExceptionHandler(Exception.class)
public void handleException(Exception ex, HttpServletRequest request) {
    // Need access to myContext from login()
}

@RequestMapping(value = "{version}/login", method = RequestMethod.POST)
public void login(HttpServletRequest request, @PathVariable String version, @RequestParam("userName") String userName, @RequestParam("password") String password, ModelMap model) throws Exception {
    ...
    myContext = "Some contextual information"
    ...
    i_will_always_throw_an_exception();
}

Since Spring is responsible for translating a thrown exception into an invocation of handleException(), I am having difficulty trying to find a way to pass myContext to the handler. One thought I have is creating a subclass of HttpServletRequest. If that approach works I would have code like this:

@ExceptionHandler(Exception.class)
public void handleException(Exception ex, MyCustomHttpServletRequest request) {
    // I now have access to the context via the following
    String myContext = request.getContext();
}

@RequestMapping(value = "{version}/login", method = RequestMethod.POST)
public void login(MyCustomHttpServletRequest request, @PathVariable String version, @RequestParam("userName") String userName, @RequestParam("password") String password, ModelMap model) throws Exception {
    ...
    myContext = "Some contextual information"
    request.setContext(myContext);
    ...
    i_will_always_throw_an_exception();
}

But, if I follow this approach, how do I properly use my own arbitrary sub-class of HttpServletRequest to make this work?

Answer 1

Can’t you just put it into exception (if necessary – wrapping the original exception with the new one)?

@ExceptionHandler(MyContextualException.class)
public void handleException(MyContextualException ex) {
    // Need access to myContext from login()
}

@RequestMapping(value = "{version}/login", method = RequestMethod.POST)
public void login(HttpServletRequest request, @PathVariable String version, @RequestParam("userName") String userName, @RequestParam("password") String password, ModelMap model) throws Exception {
    ...
    myContext = "Some contextual information"
    ...
    try {
        i_will_always_throw_an_exception();
    } catch (Exception ex) {
        throw new MyContextualException(myContext, ex);
    }
}

An alternative approach is to pass the context as a request attribute:

request.setAttribute("myContext", myContext);