日常项目开发中，进行异常处理都是非常有必要的，而不是把一些只有程序员才能看懂的错误代码抛给用户去看，所以这时候进行统一的异常处理，展现一个比较友好的错误页面就显得很有必要了。
Spring MVC提供的异常处理主要有三种方式：
- 使用 @ExceptionHandler
- 使用@ControllerAdvice 全局异常处理（Global Exception Handling）
- 自定义 HandlerExceptionResolver
使用HTTP Status Codes
首先，自定义一个异常类并使用@ResponseStatus注解，如下：
@ResponseStatus(value=HttpStatus.NOT_FOUND, reason="No such Order") // 404
public class OrderNotFoundException extends RuntimeException {
// ...
}
然后在Controller中使用，代码如下：
@RequestMapping(value="/orders/{id}", method=GET)
public String showOrder(@PathVariable("id") long id, Model model) {
Order order = orderRepository.findOrderById(id);
if (order == null) throw new OrderNotFoundException(id);
model.addAttribute(order);
return "orderDetail";
}
这样，当没有查找到订单时，会返回 HTTP 404。
基于Controller 的异常处理
我们可以使用 @ExceptionHandler 针对任意一个Controller 的中的使用@RequestMapping注解的方法就做异常处理，如下：
@Controller
public class ExceptionHandlingController {
// @RequestHandler methods
...
// Exception handling methods
// Convert a predefined exception to an HTTP Status code
@ResponseStatus(value=HttpStatus.CONFLICT,
reason="Data integrity violation") // 409
@ExceptionHandler(DataIntegrityViolationException.class)
public void conflict() {
// Nothing to do
}
// Specify name of a specific view that will be used to display the error:
@ExceptionHandler({SQLException.class,DataAccessException.class})
public String databaseError() {
// Nothing to do. Returns the logical view name of an error page, passed
// to the view-resolver(s) in usual way.
// Note that the exception is NOT available to this view (it is not added
// to the model) but see "Extending ExceptionHandlerExceptionResolver"
// below.
return "databaseError";
}
// Total control - setup a model and return the view name yourself. Or
// consider subclassing ExceptionHandlerExceptionResolver (see below).
@ExceptionHandler(Exception.class)
public ModelAndView handleError(HttpServletRequest req, Exception ex) {
logger.error("Request: " + req.getRequestURL() + " raised " + ex);
ModelAndView mav = new ModelAndView();
mav.addObject("exception", ex);
mav.addObject("url", req.getRequestURL());
mav.setViewName("error");
return mav;
}
}
全局异常处理
使用@ControllerAdvice
@ControllerAdvice
class GlobalControllerExceptionHandler {
@ResponseStatus(HttpStatus.CONFLICT) // 409
@ExceptionHandler(DataIntegrityViolationException.class)
public void handleConflict() {
// Nothing to do
}
}
捕获异常，跳转到错误页面：
@ControllerAdvice
class GlobalDefaultExceptionHandler {
public static final String DEFAULT_ERROR_VIEW = "error";
@ExceptionHandler(value = Exception.class)
public ModelAndView
defaultErrorHandler(HttpServletRequest req, Exception e) throws Exception {
// If the exception is annotated with @ResponseStatus rethrow it and let
// the framework handle it - like the OrderNotFoundException example
// at the start of this post.
// AnnotationUtils is a Spring Framework utility class.
if (AnnotationUtils.findAnnotation
(e.getClass(), ResponseStatus.class) != null)
throw e;
// Otherwise setup and send the user to a default error-view.
ModelAndView mav = new ModelAndView();
mav.addObject("exception", e);
mav.addObject("url", req.getRequestURL());
mav.setViewName(DEFAULT_ERROR_VIEW);
return mav;
}
}
参考资料
Exception Handling in Spring MVC：https://spring.io/blog/2013/11/01/exception-handling-in-spring-mvc
