【java异常】 @ControllerAdvice+@ExceptionHandler全局异常处理

叁歲伎倆 2021-12-05 01:13 324阅读 0赞

查看 @ControllerAdvice源码可见，添加了@Component；  
则@ControllerAdvice是spring的一个组件，可理解为一个实体Bean，  
可被 `<context:component-scan base-package="com.hesvit" />`  
扫描到即可；

@ControllerAdvice 可以实现三个方面的功能：

*  1 全局数据绑定 @ModelAttribute
 *  2 全局数据预处理 @InitBinder  
    1和2 请查看 [https://www.cnblogs.com/lenve/p/10748453.html][https_www.cnblogs.com_lenve_p_10748453.html] 这篇文章
 *  3 全局异常处理 @ExceptionHandler

本文主要介绍全局异常处理  
在之前的SpringMVC项目中，经常是用try…catch…来进行异常处理,实例代码如下：

@RequestMapping(value="/testException")
    	public RestBaseResult<Object> testExceptionLogin(@RequestParam String name,@RequestParam String password) { 
    		RestBaseResult<Object> result = new RestBaseResult<Object>();
    		try { 
    		    if (!password.equals("123456")) { 
    		    	result.setCode(100011);
    				result.setMsg("密码错误");
                } 
                
    			doSomething..........
    
    		sdOrderService.testExceptionLogin(name,password);
    		} catch (Exception e) { 
    			logger.error("----controller.login.errorInfo>:{}",e);
    			result.setCode(-1);
    			result.setMsg("服务器内部错误");
    		}
    		return result;
    	}

try…catch…异常的缺点： 代码冗余，不利于维护，在拦截器中的定义的错误消息无法返回到页面

### 接下来介绍一个@ControllerAdvice + @ExceptionHandler 进行全局的 Controller 层异常处理 ###

一、优缺点  
**优点：**  
异常进行统一处理；  
减少模板代码，减少编码量，提升扩展性和可维护性；  
Interceptor（拦截器）层的异常也可以被处理  
**缺点：**  
只能处理 未捕获（往外抛）的异常，对于 过滤器（Filter），Spring 框架层的异常，就无能为力了。

为了测试，所有的类都定义在exception包下：  
过滤器和拦截器的配置为贴出来了  
![在这里插入图片描述][20190718175512791.png]

/** * 全局异常处理类 * */
    @ControllerAdvice
    public class GlobalExceptionHandler { 
    
    	private Logger logger = LoggerFactory.getLogger(this.getClass());
    	
    	@ResponseStatus(code=HttpStatus.INTERNAL_SERVER_ERROR)  //自定义浏览器返回状态码，通常不需要自定义
    	@ExceptionHandler()
    	public @ResponseBody ExceptionResult handleException(Exception e,
    			HttpServletRequest request, HttpServletResponse response) { 
    		// TODO 记录log日志
            e.printStackTrace();
            logger.error("---------GlobalExceptionHandler.Exception.errorinfo>:{}",e);
            
            ExceptionResult result = new ExceptionResult();
            result.setData(e.getMessage());
            return result;
    	}
    	
    
    	@ExceptionHandler({ BusinessException.class})
    	public @ResponseBody ExceptionResult handleServiceException(BusinessException e,
    			HttpServletRequest request, HttpServletResponse response) { 
    		// TODO 记录log日志
            e.printStackTrace();
            logger.error("---------GlobalExceptionHandler.BusinessException.errorinfo>:{}",e);
            
    		ExceptionResult result = new ExceptionResult();
    		result.setCode(e.getCode());
    		result.setMsg(e.getMsg());
    		result.setData(e.getMessage());
    		return result;
    	}
    	
    	
    	@ExceptionHandler({ NullPointerException.class})
    	public @ResponseBody ExceptionResult handleServiceException(NullPointerException e,
    			HttpServletRequest request, HttpServletResponse response) { 
    		// 记录log日志
    		e.printStackTrace();
    		logger.error("---------GlobalExceptionHandler.NullPointerException.errorinfo>:{}",e);
    		
    		ExceptionResult result = new ExceptionResult();
    		result.setMsg("空指针异常");
    		result.setData(e.getMessage());
    		return result;
    	}
    
    }
    /** * -------------------BusinessException.java---------------------------------------------------- * 业务异常 */
    @Data
    @EqualsAndHashCode(callSuper=false)
    public class BusinessException extends RuntimeException { 
    
    	private static final long serialVersionUID = 1L;
    	
    	/** 异常码 */
    	private int code;
    	/** 异常提示内容 */
    	private String msg;
    	
    	
    	public BusinessException() { 
    		super();
    	}
    	public BusinessException(String msg) { 
    		super(msg);
    	}
    	public BusinessException(int code,String msg) { 
    		this.code = code;
    		this.msg = msg;
    	}
    }
    /** * -------------------ExceptionCode.java---------------------------------------------------- * 自定义异常码 */
    public class ExceptionCode { 
    	
    	/** 用户名错误 */
    	public static final int USERNAME_ERROR = 100010;
    	/** 密码错误 */
    	public static final int PWD_ERROR = 100011;
    	/** * 根据code获取MSG * @param code * @return */
    	public static String getMsgByCode(int code) { 
    		String msg = "Server internal error";
    		switch (code) { 
    			case USERNAME_ERROR:
    				msg = "用户名错误";
    				break;
    			case PWD_ERROR:
    				msg = "密码错误";
    				break;
    
    			default:
    				break;
    		}
    		return msg;
    	}
    }
    /** * --------------------------异常结果---------------------------- * */
    @Data
    public class ExceptionResult implements Serializable{ 
    	
    	private static final long serialVersionUID = 1L;
    	
    	// -- 返回代码定义 --//
    	// 按项目的规则进行定义, 比如4xx代表客户端参数错误，5xx代表服务端业务错误等.
    	public static final int SUCCESS = 0;
    	public static final int PARAMETER_ERROR = -1;
    	public static final int SYSTEM_ERROR = 500;
    	public static final String SYSTEM_SUCCESS_MESSAGE = "operate success";
    	public static final String SYSTEM_ERROR_MESSAGE = "Runtime unknown internal error.";
    
    	// -- WsResult基本属性 --//
    	private int code = PARAMETER_ERROR;
    	private String msg = SYSTEM_ERROR_MESSAGE;
    	private String currentTime = DateUtils.convertDateToString(DateUtils.DATETIME, new Date());
    	private Object data;
    }
    /** * ---------------过滤器 */
    public class TestFilter implements Filter { 
    
    	@Override
    	public void init(FilterConfig filterConfig) throws ServletException { }
    
    	@Override
    	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
    			throws IOException, ServletException { 
    		String name = request.getParameter("name");
    		if (!name.equals("admin")) { 
    			throw new BusinessException(222, "用户名错误");
    		} 
    		chain.doFilter(request, response);// 调用接口
    	}
    
    	@Override
    	public void destroy() { }
    
    }
    /** * ---------------拦截器 */
    public class TestInterceptor implements HandlerInterceptor { 
    	
    	protected Logger logger = LoggerFactory.getLogger(getClass());
    	
    	@Override
    	public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
    			throws Exception { 
    		
    		Map<String,String[]> map = request.getParameterMap();
    		Map<String,String> param = new HashMap<String,String>();
    		
    		for(Entry<String, String[]> entry : map.entrySet()) { 
    			String [] values =  entry.getValue();
    			String key = entry.getKey();
    			if(values[0] != null) { 
    				param.put(key, values[0]);
    			}
    		}
    		
    		String sign = param.get("sign");
    		if (!sign.equals("aaaaaaaaa")) { 
    			throw new BusinessException(333, "签名错误");
    		}
    		
    		return true;
    	}
    
    	@Override
    	public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
    			ModelAndView modelAndView) throws Exception { 
    	}
    
    	@Override
    	public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
    			throws Exception { 
    	}
    	
    }

测试的controller和service如下

@Controller
    @RequestMapping("/user")
    public class UserController extends BaseController{ 
    	@Autowired
    	private UserService userService;
    	
    	@RequestMapping(value="/testException")
    	public RestBaseResult<Object> testExceptionLogin(@RequestParam String name,@RequestParam String password,Model model) { 
    		
    		Map<String, Object> map = model.asMap();
    		logger.info("------>:map{}",map);
    		
    		RestBaseResult<Object> result = new RestBaseResult<Object>();
    		if (password.equals("123456")) 
    			throw new BusinessException(ExceptionCode.PWD_ERROR,ExceptionCode.getMsgByCode(ExceptionCode.PWD_ERROR));
    		
    		
    		userService.testExceptionLogin(name,password);
    		
    		return result;
    	}
    }
    ----------------service----------------------
    @service
    public class UserServiceImpl implements UserService { 
    @Override
    	public void testExceptionLogin(String name,String pwd) { 
    		User user = userDao.selectByName(name);
    		if (user == null) { 
    			throw new BusinessException(ExceptionCode.USERNAME_ERROR,ExceptionCode.getMsgByCode(ExceptionCode.USERNAME_ERROR));
    		}
    	}
    	
    }

通过Post满工具测试的结果如下图：  
处理Filter中定义的异常无法被@ExceptionHandler处理，其他的都可以，有兴趣的可以试试  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FpYXppbGlwaW5n_size_16_color_FFFFFF_t_70]

[https_www.cnblogs.com_lenve_p_10748453.html]: https://www.cnblogs.com/lenve/p/10748453.html
[20190718175512791.png]: /images/20211205/b366b12e3ed24788825252cb16370183.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FpYXppbGlwaW5n_size_16_color_FFFFFF_t_70]: /images/20211205/14f38977ff1045e3bb3a5a0757d88e58.png