03. Spring Boot Exception - SimpleMappingExceptionResolver

Instructions

Let’s make our GloablExceptionHandler as bak first, so that we can keep our code. Rename GloablExceptionHandler.java to GlobalExceptionHandler.java.bak
Create a MySimpleMappingExceptionResolver class under exceptions directory.

@Configuration
public class MySimpleMappingExceptionResolver {
   @Bean
   public SimpleMappingExceptionResolver getSimpleMappingExceptionResolver() {
       SimpleMappingExceptionResolver resolver = new SimpleMappingExceptionResolver();
       Properties mapping = new Properties();
       mapping.put("java.lang.ArithmeticException", "mathError"); //key=exception full name. value, view name
       mapping.put("java.lang.NullPointerException", "nullPointerError");
       resolver.setExceptionMappings(mapping);
       return resolver;
   }
}

If you refresh the page, you can see error is handled.

Demo

Let’s rename MySimpleMappingExceptionResolver.java to MySimpleMappingExceptionResolver.java.bak

Create MyHandlerExceptionResolver class under exceptions directory.

public class MyHandlerExceptionResolver implements HandlerExceptionResolver{
   @Override
   public ModelAndView resolveException(HttpServletRequest httpServletRequest,
                                        HttpServletResponse httpServletResponse, @Nullable Object o, Exception e) {
       ModelAndView mv = new ModelAndView();
       if (e instanceof ArithmeticException) {
           mv.setViewName("mathError");
       }
       if (e instanceof NullPointerException) {
           mv.setViewName("nullPointerError");
       }
       mv.addObject("exception", e.toString());
       return mv;
   }
}