弹簧控制器@RequestParam中的类型不匹配

Question

I am working on a spring webservice. I have created a exception resolver for handling any exceptions so that exception are sent to the client in proper format.

The exception are being caught in service layer and customized message are being sent.
Problem is if the request params in controller are of numeric type and if a user sends a string, then the defaulf message for the exception is being sent. But i want to send a customized error. Can anyone please suggest how should i do it.

Answer 1

I think you need something like this

    @RequestMapping(value = "/happy}", method = RequestMethod.POST)
public String happy(@RequestParam(value = "somevalue") int number) {
    // implement your flow
    return null;
}

@RequestMapping(value = "/happy}", method = RequestMethod.POST)
public String unhappy(@RequestParam(value = "somevalue") String string) {
    // send a custom error message to the user to use a number instead of a String
    return null;
}

Answer 2

You could try using a Spring Handler Interceptor , extracting the parameter as a string from the request itself, and check if it's numeric. You could either have one interceptor for each case and watch only on those endpoints (simpler but more classes) or generalize it to validate all the endpoint's parameters over the request.

One per case example:

public class IntTypeCheckInterceptor extends HandlerInterceptorAdapter {

    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) {
        String myIntString = request.getParameter("myInt");
        Pattern intPattern = Pattern.compile("[0-9]+");
        Matcher intMatcher = intPattern.matcher(myIntString);

        //I *think* this does the whole input
        if(!intMatcher.matches()) {
            response.sendError(HttpServletResponse.SC_BAD_REQUEST);
            return false; //false tells spring to stop processing and returns to the client
        }

        return true; //true tells spring to continue as normal
    }

}

Config:

@Override
public void addInterceptors(InterceptorRegistry registry) {
    //with this only do where the request parameter is the same name and expected to be an int
    registry.addInterceptor(new IntTypeCheckInterceptor()).paths("/your-intpath", "your-intpath2");
}

The other approach would involve checking the handler is a HandlerMethod, pulling the parameter names and types, and checking each one.

A filter should also work. I'm just more familiar with interceptors and it's inside Spring so you have all the same features available from the app context.