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

代码类

public class MyErrorController extends BasicErrorController {


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

    @SneakyThrows
    @Override
    protected Map<String, Object> getErrorAttributes(HttpServletRequest request, boolean includeStackTrace) {

        Map<String, Object> 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());

public ErrorMvcAutoConfiguration(ServerProperties serverProperties, DispatcherServletPath dispatcherServletPath,
			ObjectProvider<ErrorViewResolver> errorViewResolvers) {
		this.serverProperties = serverProperties;
		this.dispatcherServletPath = dispatcherServletPath;
		this.errorViewResolvers = errorViewResolvers.orderedStream().collect(Collectors.toList());
	}

配置类

@Configuration
public class ErrorConfiguration {

    @Bean
    public MyErrorController basicErrorController(ErrorAttributes errorAttributes, ServerProperties serverProperties,
                                                  ObjectProvider<List<ErrorViewResolver>> errorViewResolversProvider) {
        return new MyErrorController(errorAttributes, serverProperties.getError(),
                errorViewResolversProvider.getIfAvailable());
    }


}

@AdviceController

@ControllerAdvice
public class ExceptionHandler {

    @org.springframework.web.bind.annotation.ExceptionHandler(Exception.class)
    @ResponseBody
    public Result exceptionHandler(Exception e){

        e.printStackTrace();
        return new Result(StatusCode.ERROR,e.getMessage());

    }

}

拦截器异常&&URL存在,因为URL对应的controller是存在的,所以可以自定义异常处理器,返回前端自定义的协议数据,但是如果没有异常处理器 ,就会出现以下信息。

<!doctype html>
<html lang="en">

<head>
	<title>HTTP Status 500 – Internal Server Error</title>
	<style type="text/css">
		h1 {
			font-family: Tahoma, Arial, sans-serif;
			color: white;
			background-color: #525D76;
			font-size: 22px;
		}

		h2 {
			font-family: Tahoma, Arial, sans-serif;
			color: white;
			background-color: #525D76;
			font-size: 16px;
		}

		h3 {
			font-family: Tahoma, Arial, sans-serif;
			color: white;
			background-color: #525D76;
			font-size: 14px;
		}

		body {
			font-family: Tahoma, Arial, sans-serif;
			color: black;
			background-color: white;
		}

		b {
			font-family: Tahoma, Arial, sans-serif;
			color: white;
			background-color: #525D76;
		}

		p {
			font-family: Tahoma, Arial, sans-serif;
			background: white;
			color: black;
			font-size: 12px;
		}

		a {
			color: black;
		}

		a.name {
			color: black;
		}

		.line {
			height: 1px;
			background-color: #525D76;
			border: none;
		}
	</style>
</head>

<body>
	<h1>HTTP Status 500 – Internal Server Error</h1>
</body>

</html>

统一异常处理的使用:
大多数请情况下,不要去继承重写,BasicErrorController,使用@ControllerAdvice已经是够用的了,因为你的所有请求都会经过Controller

1.拦截器抛出异常,要记得要使url存在,url不存在,会抛出HTTP Status 500 – Internal Server Error异常,尽量不要在拦截器中抛异常吧
2.扩展 org.springframework.web.servlet.mvc.method.annotation.ResponseBodyAdvice 检测返回对象,必要时替换掉
3.拦截器中检测,response 状态码,重写异常数据

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