Spring全局异常处理的三种方式

比眉伴天荒 2022-04-04 08:17 224阅读 0赞

在J2EE项目的开发中，不管是对底层的数据库操作过程，还是业务层的处理过程，还是控制层的处理过程，都不可避免会遇到各种可预知的、不可预知的异常需要处理。每个过程都单独处理异常，系统的代码耦合度高，工作量大且不好统一，维护的工作量也很大。 那么，能不能将所有类型的异常处理从各处理过程解耦出来，这样既保证了相关处理过程的功能较单一，也实现了异常信息的统一处理和维护？答案是肯定的。下面将介绍使用Spring MVC统一处理异常的解决和实现过程。

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*  使用Spring MVC提供的SimpleMappingExceptionResolver
 *  实现Spring的异常处理接口HandlerExceptionResolver 自定义自己的异常处理器
 *  使用@ExceptionHandler注解实现异常处理

### 一. SimpleMappingExceptionResolver ###

使用这种方式具有集成简单、有良好的扩展性、对已有代码没有入侵性等优点，但该方法仅能获取到异常信息，若在出现异常时，对需要获取除异常以外的数据的情况不适用。

@Configuration
    @EnableWebMvc
    @ComponentScan(basePackages = {"com.rz.mvc.web"})
    public class WebMVCConfig extends WebMvcConfigurerAdapter{
     @Bean
     public SimpleMappingExceptionResolver simpleMappingExceptionResolver()
     {
     SimpleMappingExceptionResolver b = new SimpleMappingExceptionResolver();
     Properties mappings = new Properties();
     mappings.put("org.springframework.web.servlet.PageNotFound", "page-404");
     mappings.put("org.springframework.dao.DataAccessException", "data-access");
     mappings.put("org.springframework.transaction.TransactionException", "transaction-Failure");
     b.setExceptionMappings(mappings);
     return b;
     }
    }

### 二. HandlerExceptionResolver ###

相比第一种来说,HandlerExceptionResolver能准确显示定义的异常处理页面,达到了统一异常处理的目标

1.定义一个类实现HandlerExceptionResolver接口

public class GlobalHandlerExceptionResolver implements HandlerExceptionResolver { 
    
         private static final Logger LOG = LoggerFactory.getLogger(GlobalHandlerExceptionResolver.class); 
     /** 
     * 在这里处理所有得异常信息 
     */ 
     @Override 
     public ModelAndView resolveException(HttpServletRequest req, HttpServletResponse resp, 
          Object o, Exception ex) { 
         ex.printStackTrace(); 
         if (ex instanceof AthenaException) { 
             //AthenaException为一个自定义异常
               ex.printStackTrace(); 
               printWrite(ex.toString(), resp); 
               return new ModelAndView(); 
         } 
    
        //RspMsg为一个自定义处理异常信息的类 
        //ResponseCode为一个自定义错误码的接口
          RspMsg unknownException = null; 
         if (ex instanceof NullPointerException) { 
               unknownException = new RspMsg(ResponseCode.CODE_UNKNOWN, "业务判空异常", null);
         } else { 
               unknownException = new RspMsg(ResponseCode.CODE_UNKNOWN, ex.getMessage(), null); 
         } 
          printWrite(unknownException.toString(), resp); 
          return new ModelAndView(); 
     } 
    
     /** 
     * 将错误信息添加到response中 
     * 
     * @param msg 
     * @param response 
     * @throws IOException 
     */ 
     public static void printWrite(String msg, HttpServletResponse response) { 
       try { 
            PrintWriter pw = response.getWriter(); 
            pw.write(msg); 
            pw.flush(); 
            pw.close(); 
       } catch (Exception e) { 
            e.printStackTrace(); 
       } 
     }
    
    }

这种方式实现的异常处理，可以针对不同的异常和自己定义的异常码进行翻译，然后输出到response中，在前端展示。

### 三 . ExceptionHandler ###

1.首先定义一个父类,实现一些基础的方法

public class BaseGlobalExceptionHandler { 
    
     protected static final Logger logger = null; 
     protected static final String DEFAULT_ERROR_MESSAGE = "系统忙，请稍后再试"; 
     protected ModelAndView handleError(HttpServletRequest req, HttpServletResponse rsp, Exception e, String viewName, HttpStatus status) throws Exception { 
     
    	 if (AnnotationUtils.findAnnotation(e.getClass(), ResponseStatus.class) != null) 
    	 throw e; 
    	 String errorMsg = e instanceof MessageException ? e.getMessage() : DEFAULT_ERROR_MESSAGE; 
    	 String errorStack = Throwables.getStackTraceAsString(e); 
    	 getLogger().error("Request: {} raised {}", req.getRequestURI(), errorStack); 
    	 if (Ajax.isAjax(req)) { 
    		 return handleAjaxError(rsp, errorMsg, status); 
    	 } 
         return handleViewError(req.getRequestURL().toString(), errorStack, errorMsg, viewName); 
     } 
     
     protected ModelAndView handleViewError(String url, String errorStack, String errorMessage, String viewName) { 
    	 ModelAndView mav = new ModelAndView(); 
    	 mav.addObject("exception", errorStack); 
    	 mav.addObject("url", url); 
    	 mav.addObject("message", errorMessage); 
    	 mav.addObject("timestamp", new Date()); 
    	 mav.setViewName(viewName); 
    	 return mav; 
     } 
     
     protected ModelAndView handleAjaxError(HttpServletResponse rsp, String errorMessage, HttpStatus status) throws IOException { 
    	 rsp.setCharacterEncoding("UTF-8"); 
    	 rsp.setStatus(status.value()); 
    	 PrintWriter writer = rsp.getWriter();
    	 writer.write(errorMessage); 
    	 writer.flush(); 
    	 return null; 
     } 
     
     public Logger getLogger() { 
         return LoggerFactory.getLogger(BaseGlobalExceptionHandler.class);
     } 
     
    }

2.针对你需要捕捉的异常实现相对应的处理方式

@ControllerAdvice
    public class GlobalExceptionHandler extends BaseGlobalExceptionHandler { 
    
    	 //比如404的异常就会被这个方法捕获
    	 @ExceptionHandler(NoHandlerFoundException.class) 
    	 @ResponseStatus(HttpStatus.NOT_FOUND) 
    	 public ModelAndView handle404Error(HttpServletRequest req, HttpServletResponse rsp, Exception e) throws Exception { 
    	      return handleError(req, rsp, e, "error-front", HttpStatus.NOT_FOUND); 
    	 } 
    	 
    	 //500的异常会被这个方法捕获
    	 @ExceptionHandler(Exception.class) 
    	 @ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR) 
    	 public ModelAndView handleError(HttpServletRequest req, HttpServletResponse rsp, Exception e) throws Exception { 
    	      return handleError(req, rsp, e, "error-front", HttpStatus.INTERNAL_SERVER_ERROR); 
    	 } 
    	 
    	 //TODO 你也可以再写一个方法来捕获你的自定义异常
    	 //TRY NOW!!!
    	 @Override 
    	 public Logger getLogger() { 
    	      return LoggerFactory.getLogger(GlobalExceptionHandler.class); 
    	 }
     }

另附：[怎么优雅的处理Java异常？][Java]

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