SpringBoot异常处理机制
在SpringBoot中，常用的异常处理有两种，一种是BasicErrorController，另一种是@ControllerAdvice，BasicErrorController用于处理非Controller抛出的异常，而@ControllerAdvice用于处理Controller抛出的异常，对于非Controller抛出的异常它是不会管的。

但是，如果是Controller层调用Service层，从Service层抛出，依然会抛到Controller，所以还是会调用@ControllerAdvice进行处理

以BasicErrorController为例，我们如何去创建一个自定的异常处理类呐？

BasicErrorController创建及配置
创建代码类并继承BasicErrorController

public class MyErrorController extends BasicErrorController {


    public MyErrorController(ErrorAttributes errorAttributes, ErrorProperties errorProperties, List errorViewResolvers) {
        super(errorAttributes, errorProperties, errorViewResolvers);
    }

    @SneakyThrows
    @Override
    protected Map getErrorAttributes(HttpServletRequest request, boolean includeStackTrace) {

        Map attributes = super.getErrorAttributes(request, includeStackTrace);
        attributes.remove("timestamp");
        attributes.remove("status");
        attributes.remove("error");
        attributes.remove("exception");
        attributes.remove("path");
        String messageCode = (String) attributes.get("message");
        ErrorEnum errorEnum = null;
        try {
            errorEnum = ErrorEnum.getEnumByCode(messageCode);
        } catch (Exception e) {
            e.printStackTrace();
        }

        if (errorEnum==null){

            attributes.put("type","0");
            attributes.put("message","枚举类异常");
            return attributes;

        }

        attributes.put("errorControllerType","basicErrorController");
        attributes.put("type",errorEnum.getCode());
        attributes.put("message",errorEnum.getMessage());
        return attributes;
    }
}

配置MyErrorController
首先我们知道SpringBoot的大部分配置可以在ErrorMvcAutoConfiguration中找到，打开ErrorMvcAutoConfiguration源码，可以看到ErrorMvcAutoConfiguration中对

BasicErrorController进行了配置，为此在继承BasicErrorController后也应当对继承类进行配置。

ErrorMvcAutoConfiguration中的BasicErrorController配置如下

@Bean
	@ConditionalOnMissingBean(value = ErrorController.class, search = SearchStrategy.CURRENT)
	public BasicErrorController basicErrorController(ErrorAttributes errorAttributes) {
		return new BasicErrorController(errorAttributes, this.serverProperties.getError(), this.errorViewResolvers);
	}

我们知道，需要ErrorAttributes errorAttributes, ErrorProperties errorProperties, List errorViewResolvers，三个参数，而ErrorMvcAutoConfiguration源码中配置中只有ErrorAttributes errorAttributes一个参数，而另外一个参数则在new BasicErrorController(errorAttributes, this.serverProperties.getError(), this.errorViewResolvers) 中找到，即his.serverProperties.getError(),最后一个参数点两下，可以知道在ErrorMvcAutoConfiguration构造函数中，即this.errorViewResolvers = errorViewResolvers.orderedStream().collect(Collectors.toList());

@Controller
@RequestMapping({"${server.error.path:${error.path:/error}}"})
public class CustomErrorController extends BasicErrorController {

    public CustomErrorController(ErrorAttributes errorAttributes, ServerProperties serverProperties,
                                 ObjectProvider> errorViewResolversProvider) {
        super(errorAttributes, serverProperties.getError(),
                (List)errorViewResolversProvider.orderedStream().collect(Collectors.toList()));
    }

    @RequestMapping
    public ResponseEntity> error(HttpServletRequest request) {
        HttpStatus status = super.getStatus(request);
        if (status == HttpStatus.NO_CONTENT) {
            return new ResponseEntity(status);
        } else {
            Map body = this.getErrorAttributes(request, this.isIncludeStackTrace(request, MediaType.ALL));
            body.put("resp_msg", body.get("message"));
            body.put("resp_code", body.get("status"));
            body.remove("status");
            body.remove("message");
            return new ResponseEntity(body, status);
        }
    }
}

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