前言
Springmvc 中 异常解析器的默认实现有 ExceptionHandlerExceptionResolver、ResponseStatusExceptionResolver和DefaultHandlerExceptionResolver 等，都实现同一的接口 HandlerExceptionResolver。
一、HandlerExceptionResolver
接口中只有一个解析异常的方法
public interface HandlerExceptionResolver {
@Nullable
ModelAndView resolveException(
HttpServletRequest request, HttpServletResponse response, @Nullable Object handler, Exception ex);
}
二、自定义 HandlerExceptionResolver
public class CustomHandlerExceptionResolver implements HandlerExceptionResolver {
private static String msg = "服务器错误";
@Override
public ModelAndView resolveException(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) {
if (e instanceof RuntimeException) {
ModelAndView modelAndView = new ModelAndView(new MappingJackson2JsonView());
modelAndView.addObject("message", e.getMessage());
modelAndView.addObject("code", 500);
return modelAndView;
} else {
return null;
}
}
}
三、注册
@Configuration
public class HandlerExceptionResolverConfig implements WebMvcConfigurer {
public void configureHandlerExceptionResolvers(List<HandlerExceptionResolver> resolvers) {
//注册自定义异常解析器
resolvers.add(new CustomHandlerExceptionResolver());
}
}
注意，如果注册了自定义的异常解析器，则默认的异常解析器就不会生效了，像全局异常处理 @ControllerAdvice 就失效了，在源码中是这样的：
@Bean
public HandlerExceptionResolver handlerExceptionResolver(
@Qualifier("mvcContentNegotiationManager") ContentNegotiationManager contentNegotiationManager) {
List<HandlerExceptionResolver> exceptionResolvers = new ArrayList<>();
//加载自定义异常解析器
configureHandlerExceptionResolvers(exceptionResolvers);
if (exceptionResolvers.isEmpty()) {
//没有自定义异常解析器，才会进入这里，将默认的异常解析器加载进来
addDefaultHandlerExceptionResolvers(exceptionResolvers, contentNegotiationManager);
}
//扩展异常解析器
extendHandlerExceptionResolvers(exceptionResolvers);
HandlerExceptionResolverComposite composite = new HandlerExceptionResolverComposite();
composite.setOrder(0);
composite.setExceptionResolvers(exceptionResolvers);
return composite;
}