一：springboot错误页面解析返回原理归纳

2023-11-26 12:37:52

1：页面呈现

常见的错误页面

这个空白页面主要包括 默认错误路径、时间戳、错误提示消息和错误状态码

但如果我们使用其他的客户端（非浏览器），例如 Postman工具发送 http://127.0.0.1:8080/noPage 请求时，默认响应客户端的是JSON数据，如下图所示

响应完整信息如上图

2：原理分析

出现上面的两种默认效果的原因是 SpringBoot容器为我们自动配置了错误处理自动配置的控制器 ErrorMvcAutoConfiguration

我们首先看看程序启动，springboot容器里的bean

以下是一个常见的springboot启动类改写的

package com.foxconn.sw.macaddress;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.transaction.annotation.EnableTransactionManagement;

//事务管理
@EnableTransactionManagement
//会自动 装配指定包下面所有Mapper，省得在每个Mapper上面写@Mapper
@MapperScan("com.foxconn.sw.macaddress.dao")
@SpringBootApplication
public class MacaddressApplication {
    public static void main(String[] args) {
        SpringApplication.run(MacaddressApplication.class, args);
    }
}

获取一下初始化的bean

package com.foxconn.sw.macaddress;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.transaction.annotation.EnableTransactionManagement;

//事务管理
@EnableTransactionManagement
//会自动 装配指定包下面所有Mapper，省得在每个Mapper上面写@Mapper
@MapperScan("com.foxconn.sw.macaddress.dao")
@SpringBootApplication
public class MacaddressApplication {
    public static void main(String[] args) {
        ConfigurableApplicationContext run = SpringApplication.run(MacaddressApplication.class, args);
        String[] beanDefinitionNames = run.getBeanDefinitionNames();
        for (int i = 0; i < beanDefinitionNames.length; i++) {
            String beanDefinitionName = beanDefinitionNames[i];
            System.err.println(beanDefinitionName);
        }
    }
}

这样我们就可以得到IOC容器初始化的beanName，以下是完整结果，其中就包含一些spring整合springmvc的如dispatcherServlet,文件上传，视图解析器mvcviewResolver等

org.springframework.context.annotation.internalConfigurationAnnotationProcessor
org.springframework.context.annotation.internalAutowiredAnnotationProcessor
org.springframework.context.annotation.internalCommonAnnotationProcessor
org.springframework.context.annotation.internalPersistenceAnnotationProcessor
org.springframework.context.event.internalEventListenerProcessor
org.springframework.context.event.internalEventListenerFactory
macaddressApplication
org.springframework.boot.autoconfigure.internalCachingMetadataReaderFactory
druidConfig
myBatisConfig
springMvcConfiguer
applicationController
deliveryRecordController
loginController
macaddressController
userController
applicationService
deliveryRecordService
macaddressService
userServiceImpl
druidDataSource
druidServlet
filterRegistrationBean
configurationCustomizer
localeResolver
org.springframework.transaction.annotation.ProxyTransactionManagementConfiguration
org.springframework.transaction.config.internalTransactionAdvisor
transactionAttributeSource
transactionInterceptor
org.springframework.transaction.config.internalTransactionalEventListenerFactory
org.springframework.aop.config.internalAutoProxyCreator
com.foxconn.sw.macaddress.MacaddressApplication#MapperScannerRegistrar#0
org.springframework.boot.autoconfigure.AutoConfigurationPackages
org.springframework.boot.autoconfigure.context.MessageSourceAutoConfiguration
messageSourceProperties
messageSource
org.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessor
org.springframework.boot.context.internalConfigurationPropertiesBinderFactory
org.springframework.boot.context.internalConfigurationPropertiesBinder
org.springframework.boot.context.properties.ConfigurationPropertiesBeanDefinitionValidator
org.springframework.boot.context.properties.ConfigurationBeanFactoryMetadata
org.springframework.boot.autoconfigure.context.PropertyPlaceholderAutoConfiguration
propertySourcesPlaceholderConfigurer
org.springframework.boot.autoconfigure.websocket.servlet.WebSocketServletAutoConfiguration$TomcatWebSocketConfiguration
websocketServletWebServerCustomizer
org.springframework.boot.autoconfigure.websocket.servlet.WebSocketServletAutoConfiguration
org.springframework.boot.autoconfigure.web.servlet.ServletWebServerFactoryConfiguration$EmbeddedTomcat
tomcatServletWebServerFactory
org.springframework.boot.autoconfigure.web.servlet.ServletWebServerFactoryAutoConfiguration
servletWebServerFactoryCustomizer
tomcatServletWebServerFactoryCustomizer
server-org.springframework.boot.autoconfigure.web.ServerProperties
webServerFactoryCustomizerBeanPostProcessor
errorPageRegistrarBeanPostProcessor
org.springframework.boot.autoconfigure.web.servlet.DispatcherServletAutoConfiguration$DispatcherServletConfiguration
dispatcherServlet
spring.mvc-org.springframework.boot.autoconfigure.web.servlet.WebMvcProperties
spring.http-org.springframework.boot.autoconfigure.http.HttpProperties
org.springframework.boot.autoconfigure.web.servlet.DispatcherServletAutoConfiguration$DispatcherServletRegistrationConfiguration
dispatcherServletRegistration
org.springframework.boot.autoconfigure.web.servlet.DispatcherServletAutoConfiguration
org.springframework.boot.autoconfigure.task.TaskExecutionAutoConfiguration
taskExecutorBuilder
applicationTaskExecutor
spring.task.execution-org.springframework.boot.autoconfigure.task.TaskExecutionProperties
org.springframework.boot.autoconfigure.validation.ValidationAutoConfiguration
defaultValidator
methodValidationPostProcessor
org.springframework.boot.autoconfigure.web.servlet.error.ErrorMvcAutoConfiguration$WhitelabelErrorViewConfiguration
error
beanNameViewResolver
org.springframework.boot.autoconfigure.web.servlet.error.ErrorMvcAutoConfiguration$DefaultErrorViewResolverConfiguration
conventionErrorViewResolver
org.springframework.boot.autoconfigure.web.servlet.error.ErrorMvcAutoConfiguration
errorAttributes
basicErrorController
errorPageCustomizer
preserveErrorControllerTargetClassPostProcessor
spring.resources-org.springframework.boot.autoconfigure.web.ResourceProperties
org.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfiguration$EnableWebMvcConfiguration
requestMappingHandlerAdapter
requestMappingHandlerMapping
welcomePageHandlerMapping
mvcConversionService
mvcValidator
mvcContentNegotiationManager
mvcPathMatcher
mvcUrlPathHelper
viewControllerHandlerMapping
beanNameHandlerMapping
routerFunctionMapping
resourceHandlerMapping
mvcResourceUrlProvider
defaultServletHandlerMapping
handlerFunctionAdapter
mvcUriComponentsContributor
httpRequestHandlerAdapter
simpleControllerHandlerAdapter
handlerExceptionResolver
mvcViewResolver
mvcHandlerMappingIntrospector
org.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfiguration$WebMvcAutoConfigurationAdapter
defaultViewResolver
viewResolver
requestContextFilter
org.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfiguration
hiddenHttpMethodFilter
formContentFilter
org.springframework.boot.autoconfigure.transaction.jta.JtaAutoConfiguration
org.springframework.boot.autoconfigure.jdbc.metadata.DataSourcePoolMetadataProvidersConfiguration$HikariPoolDataSourceMetadataProviderConfiguration
hikariPoolDataSourceMetadataProvider
org.springframework.boot.autoconfigure.jdbc.metadata.DataSourcePoolMetadataProvidersConfiguration
org.springframework.boot.autoconfigure.jdbc.DataSourceInitializerInvoker
org.springframework.boot.autoconfigure.jdbc.DataSourceInitializationConfiguration
dataSourceInitializerPostProcessor
org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration
spring.datasource-org.springframework.boot.autoconfigure.jdbc.DataSourceProperties
org.mybatis.spring.boot.autoconfigure.MybatisLanguageDriverAutoConfiguration
org.mybatis.spring.boot.autoconfigure.MybatisAutoConfiguration
sqlSessionFactory
sqlSessionTemplate
mybatis-org.mybatis.spring.boot.autoconfigure.MybatisProperties
com.github.pagehelper.autoconfigure.PageHelperAutoConfiguration
pageHelperProperties
pagehelper-com.github.pagehelper.autoconfigure.PageHelperProperties
org.springframework.boot.autoconfigure.jmx.JmxAutoConfiguration
mbeanExporter
objectNamingStrategy
mbeanServer
org.springframework.boot.autoconfigure.admin.SpringApplicationAdminJmxAutoConfiguration
springApplicationAdminRegistrar
org.springframework.boot.autoconfigure.aop.AopAutoConfiguration$AspectJAutoProxyingConfiguration$CglibAutoProxyConfiguration
org.springframework.boot.autoconfigure.aop.AopAutoConfiguration$AspectJAutoProxyingConfiguration
org.springframework.boot.autoconfigure.aop.AopAutoConfiguration
org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaConfiguration
transactionManager
jpaVendorAdapter
entityManagerFactoryBuilder
entityManagerFactory
spring.jpa.hibernate-org.springframework.boot.autoconfigure.orm.jpa.HibernateProperties
spring.jpa-org.springframework.boot.autoconfigure.orm.jpa.JpaProperties
dataSourceInitializedPublisher
org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration
org.springframework.boot.autoconfigure.context.ConfigurationPropertiesAutoConfiguration
org.springframework.boot.autoconfigure.dao.PersistenceExceptionTranslationAutoConfiguration
persistenceExceptionTranslationPostProcessor
org.springframework.boot.autoconfigure.data.jpa.JpaRepositoriesAutoConfiguration
emBeanDefinitionRegistrarPostProcessor
jpaMappingContext
jpaContext
org.springframework.data.jpa.util.JpaMetamodelCacheCleanup
org.springframework.data.jpa.repository.support.JpaEvaluationContextExtension
org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration$Jackson2ObjectMapperBuilderCustomizerConfiguration
standardJacksonObjectMapperBuilderCustomizer
spring.jackson-org.springframework.boot.autoconfigure.jackson.JacksonProperties
org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration$JacksonObjectMapperBuilderConfiguration
jacksonObjectMapperBuilder
org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration$ParameterNamesModuleConfiguration
parameterNamesModule
org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration$JacksonObjectMapperConfiguration
jacksonObjectMapper
org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration
jsonComponentModule
org.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfiguration$StringHttpMessageConverterConfiguration
stringHttpMessageConverter
org.springframework.boot.autoconfigure.http.JacksonHttpMessageConvertersConfiguration$MappingJackson2HttpMessageConverterConfiguration
mappingJackson2HttpMessageConverter
org.springframework.boot.autoconfigure.http.JacksonHttpMessageConvertersConfiguration
org.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfiguration
messageConverters
org.springframework.data.web.config.ProjectingArgumentResolverRegistrar
projectingArgumentResolverBeanPostProcessor
org.springframework.data.web.config.SpringDataWebConfiguration
pageableResolver
sortResolver
org.springframework.data.web.config.SpringDataJacksonConfiguration
jacksonGeoModule
org.springframework.boot.autoconfigure.data.web.SpringDataWebAutoConfiguration
pageableCustomizer
sortCustomizer
spring.data.web-org.springframework.boot.autoconfigure.data.web.SpringDataWebProperties
org.springframework.boot.autoconfigure.h2.H2ConsoleAutoConfiguration
h2Console
spring.h2.console-org.springframework.boot.autoconfigure.h2.H2ConsoleProperties
org.springframework.boot.autoconfigure.info.ProjectInfoAutoConfiguration
spring.info-org.springframework.boot.autoconfigure.info.ProjectInfoProperties
org.springframework.boot.autoconfigure.jdbc.JdbcTemplateConfiguration
jdbcTemplate
org.springframework.boot.autoconfigure.jdbc.NamedParameterJdbcTemplateConfiguration
namedParameterJdbcTemplate
org.springframework.boot.autoconfigure.jdbc.JdbcTemplateAutoConfiguration
spring.jdbc-org.springframework.boot.autoconfigure.jdbc.JdbcProperties
org.springframework.boot.autoconfigure.security.oauth2.resource.servlet.OAuth2ResourceServerAutoConfiguration
spring.security.oauth2.resourceserver-org.springframework.boot.autoconfigure.security.oauth2.resource.OAuth2ResourceServerProperties
org.springframework.boot.autoconfigure.task.TaskSchedulingAutoConfiguration
taskSchedulerBuilder
spring.task.scheduling-org.springframework.boot.autoconfigure.task.TaskSchedulingProperties
org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration$ThymeleafJava8TimeDialect
java8TimeDialect
org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration$ThymeleafWebMvcConfiguration$ThymeleafViewResolverConfiguration
thymeleafViewResolver
org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration$ThymeleafWebMvcConfiguration
org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration$ThymeleafDefaultConfiguration
templateEngine
org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration$DefaultTemplateResolverConfiguration
defaultTemplateResolver
org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration
spring.thymeleaf-org.springframework.boot.autoconfigure.thymeleaf.ThymeleafProperties
org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration$DataSourceTransactionManagerConfiguration
org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration
org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration$TransactionTemplateConfiguration
transactionTemplate
org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration
platformTransactionManagerCustomizers
spring.transaction-org.springframework.boot.autoconfigure.transaction.TransactionProperties
org.springframework.boot.autoconfigure.web.client.RestTemplateAutoConfiguration
restTemplateBuilder
org.springframework.boot.autoconfigure.web.embedded.EmbeddedWebServerFactoryCustomizerAutoConfiguration$TomcatWebServerFactoryCustomizerConfiguration
tomcatWebServerFactoryCustomizer
org.springframework.boot.autoconfigure.web.embedded.EmbeddedWebServerFactoryCustomizerAutoConfiguration
org.springframework.boot.autoconfigure.web.servlet.HttpEncodingAutoConfiguration
characterEncodingFilter
localeCharsetMappingsCustomizer
org.springframework.boot.autoconfigure.web.servlet.MultipartAutoConfiguration
multipartConfigElement
multipartResolver
spring.servlet.multipart-org.springframework.boot.autoconfigure.web.servlet.MultipartProperties
org.springframework.boot.devtools.autoconfigure.LocalDevToolsAutoConfiguration$RestartConfiguration
restartingClassPathChangedEventListener
classPathFileSystemWatcher
classPathRestartStrategy
fileSystemWatcherFactory
conditionEvaluationDeltaLoggingListener
org.springframework.boot.devtools.autoconfigure.LocalDevToolsAutoConfiguration$LiveReloadConfiguration
liveReloadServer
optionalLiveReloadServer
liveReloadServerEventListener
org.springframework.boot.devtools.autoconfigure.LocalDevToolsAutoConfiguration
spring.devtools-org.springframework.boot.devtools.autoconfigure.DevToolsProperties
applicationDao
deliveryRecordDao
macaddressDao
userDao
org.springframework.orm.jpa.SharedEntityManagerCreator#0

查找一下

回到开头的ErrorMvcAutoConfiguration

/*
 * Copyright 2012-2019 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.boot.autoconfigure.web.servlet.error;

import java.nio.charset.StandardCharsets;
import java.util.Date;
import java.util.Map;
import java.util.stream.Collectors;

import javax.servlet.Servlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.aop.framework.autoproxy.AutoProxyUtils;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.ObjectProvider;
import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.boot.autoconfigure.AutoConfigureBefore;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.condition.ConditionMessage;
import org.springframework.boot.autoconfigure.condition.ConditionOutcome;
import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication.Type;
import org.springframework.boot.autoconfigure.condition.SearchStrategy;
import org.springframework.boot.autoconfigure.condition.SpringBootCondition;
import org.springframework.boot.autoconfigure.template.TemplateAvailabilityProvider;
import org.springframework.boot.autoconfigure.template.TemplateAvailabilityProviders;
import org.springframework.boot.autoconfigure.web.ResourceProperties;
import org.springframework.boot.autoconfigure.web.ServerProperties;
import org.springframework.boot.autoconfigure.web.servlet.DispatcherServletPath;
import org.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfiguration;
import org.springframework.boot.autoconfigure.web.servlet.WebMvcProperties;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.boot.web.server.ErrorPage;
import org.springframework.boot.web.server.ErrorPageRegistrar;
import org.springframework.boot.web.server.ErrorPageRegistry;
import org.springframework.boot.web.server.WebServerFactoryCustomizer;
import org.springframework.boot.web.servlet.error.DefaultErrorAttributes;
import org.springframework.boot.web.servlet.error.ErrorAttributes;
import org.springframework.boot.web.servlet.error.ErrorController;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ConditionContext;
import org.springframework.context.annotation.Conditional;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.Ordered;
import org.springframework.core.type.AnnotatedTypeMetadata;
import org.springframework.http.MediaType;
import org.springframework.web.servlet.DispatcherServlet;
import org.springframework.web.servlet.View;
import org.springframework.web.servlet.view.BeanNameViewResolver;
import org.springframework.web.util.HtmlUtils;

/**
 * {@link EnableAutoConfiguration Auto-configuration} to render errors via an MVC error
 * controller.
 *
 * @author Dave Syer
 * @author Andy Wilkinson
 * @author Stephane Nicoll
 * @author Brian Clozel
 * @since 1.0.0
 */
@Configuration(proxyBeanMethods = false)
@ConditionalOnWebApplication(type = Type.SERVLET)
@ConditionalOnClass({ Servlet.class, DispatcherServlet.class })
// Load before the main WebMvcAutoConfiguration so that the error View is available
@AutoConfigureBefore(WebMvcAutoConfiguration.class)
@EnableConfigurationProperties({ ServerProperties.class, ResourceProperties.class, WebMvcProperties.class })
public class ErrorMvcAutoConfiguration {

	private final ServerProperties serverProperties;

	public ErrorMvcAutoConfiguration(ServerProperties serverProperties) {
		this.serverProperties = serverProperties;
	}

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

	@Bean
	@ConditionalOnMissingBean(value = ErrorController.class, search = SearchStrategy.CURRENT)
	public BasicErrorController basicErrorController(ErrorAttributes errorAttributes,
			ObjectProvider<ErrorViewResolver> errorViewResolvers) {
		return new BasicErrorController(errorAttributes, this.serverProperties.getError(),
				errorViewResolvers.orderedStream().collect(Collectors.toList()));
	}

	@Bean
	public ErrorPageCustomizer errorPageCustomizer(DispatcherServletPath dispatcherServletPath) {
		return new ErrorPageCustomizer(this.serverProperties, dispatcherServletPath);
	}

	@Bean
	public static PreserveErrorControllerTargetClassPostProcessor preserveErrorControllerTargetClassPostProcessor() {
		return new PreserveErrorControllerTargetClassPostProcessor();
	}

	@Configuration(proxyBeanMethods = false)
	static class DefaultErrorViewResolverConfiguration {

		private final ApplicationContext applicationContext;

		private final ResourceProperties resourceProperties;

		DefaultErrorViewResolverConfiguration(ApplicationContext applicationContext,
				ResourceProperties resourceProperties) {
			this.applicationContext = applicationContext;
			this.resourceProperties = resourceProperties;
		}

		@Bean
		@ConditionalOnBean(DispatcherServlet.class)
		@ConditionalOnMissingBean(ErrorViewResolver.class)
		DefaultErrorViewResolver conventionErrorViewResolver() {
			return new DefaultErrorViewResolver(this.applicationContext, this.resourceProperties);
		}

	}

	@Configuration(proxyBeanMethods = false)
	@ConditionalOnProperty(prefix = "server.error.whitelabel", name = "enabled", matchIfMissing = true)
	@Conditional(ErrorTemplateMissingCondition.class)
	protected static class WhitelabelErrorViewConfiguration {

		private final StaticView defaultErrorView = new StaticView();

		@Bean(name = "error")
		@ConditionalOnMissingBean(name = "error")
		public View defaultErrorView() {
			return this.defaultErrorView;
		}

		// If the user adds @EnableWebMvc then the bean name view resolver from
		// WebMvcAutoConfiguration disappears, so add it back in to avoid disappointment.
		@Bean
		@ConditionalOnMissingBean
		public BeanNameViewResolver beanNameViewResolver() {
			BeanNameViewResolver resolver = new BeanNameViewResolver();
			resolver.setOrder(Ordered.LOWEST_PRECEDENCE - 10);
			return resolver;
		}

	}

	/**
	 * {@link SpringBootCondition} that matches when no error template view is detected.
	 */
	private static class ErrorTemplateMissingCondition extends SpringBootCondition {

		@Override
		public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {
			ConditionMessage.Builder message = ConditionMessage.forCondition("ErrorTemplate Missing");
			TemplateAvailabilityProviders providers = new TemplateAvailabilityProviders(context.getClassLoader());
			TemplateAvailabilityProvider provider = providers.getProvider("error", context.getEnvironment(),
					context.getClassLoader(), context.getResourceLoader());
			if (provider != null) {
				return ConditionOutcome.noMatch(message.foundExactly("template from " + provider));
			}
			return ConditionOutcome.match(message.didNotFind("error template view").atAll());
		}

	}

	/**
	 * Simple {@link View} implementation that writes a default HTML error page.
	 */
	private static class StaticView implements View {

		private static final MediaType TEXT_HTML_UTF8 = new MediaType("text", "html", StandardCharsets.UTF_8);

		private static final Log logger = LogFactory.getLog(StaticView.class);

		@Override
		public void render(Map<String, ?> model, HttpServletRequest request, HttpServletResponse response)
				throws Exception {
			if (response.isCommitted()) {
				String message = getMessage(model);
				logger.error(message);
				return;
			}
			response.setContentType(TEXT_HTML_UTF8.toString());
			StringBuilder builder = new StringBuilder();
			Date timestamp = (Date) model.get("timestamp");
			Object message = model.get("message");
			Object trace = model.get("trace");
			if (response.getContentType() == null) {
				response.setContentType(getContentType());
			}
			builder.append("<html><body><h1>Whitelabel Error Page</h1>").append(
					"<p>This application has no explicit mapping for /error, so you are seeing this as a fallback.</p>")
					.append("<div id='created'>").append(timestamp).append("</div>")
					.append("<div>There was an unexpected error (type=").append(htmlEscape(model.get("error")))
					.append(", status=").append(htmlEscape(model.get("status"))).append(").</div>");
			if (message != null) {
				builder.append("<div>").append(htmlEscape(message)).append("</div>");
			}
			if (trace != null) {
				builder.append("<div style='white-space:pre-wrap;'>").append(htmlEscape(trace)).append("</div>");
			}
			builder.append("</body></html>");
			response.getWriter().append(builder.toString());
		}

		private String htmlEscape(Object input) {
			return (input != null) ? HtmlUtils.htmlEscape(input.toString()) : null;
		}

		private String getMessage(Map<String, ?> model) {
			Object path = model.get("path");
			String message = "Cannot render error page for request [" + path + "]";
			if (model.get("message") != null) {
				message += " and exception [" + model.get("message") + "]";
			}
			message += " as the response has already been committed.";
			message += " As a result, the response may have the wrong status code.";
			return message;
		}

		@Override
		public String getContentType() {
			return "text/html";
		}

	}

	/**
	 * {@link WebServerFactoryCustomizer} that configures the server's error pages.
	 */
	private static class ErrorPageCustomizer implements ErrorPageRegistrar, Ordered {

		private final ServerProperties properties;

		private final DispatcherServletPath dispatcherServletPath;

		protected ErrorPageCustomizer(ServerProperties properties, DispatcherServletPath dispatcherServletPath) {
			this.properties = properties;
			this.dispatcherServletPath = dispatcherServletPath;
		}

		@Override
		public void registerErrorPages(ErrorPageRegistry errorPageRegistry) {
			ErrorPage errorPage = new ErrorPage(
					this.dispatcherServletPath.getRelativePath(this.properties.getError().getPath()));
			errorPageRegistry.addErrorPages(errorPage);
		}

		@Override
		public int getOrder() {
			return 0;
		}

	}

	/**
	 * {@link BeanFactoryPostProcessor} to ensure that the target class of ErrorController
	 * MVC beans are preserved when using AOP.
	 */
	static class PreserveErrorControllerTargetClassPostProcessor implements BeanFactoryPostProcessor {

		@Override
		public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
			String[] errorControllerBeans = beanFactory.getBeanNamesForType(ErrorController.class, false, false);
			for (String errorControllerBean : errorControllerBeans) {
				try {
					beanFactory.getBeanDefinition(errorControllerBean)
							.setAttribute(AutoProxyUtils.PRESERVE_TARGET_CLASS_ATTRIBUTE, Boolean.TRUE);
				}
				catch (Throwable ex) {
					// Ignore
				}
			}
		}

	}

}

render（）就是图一出来的结果的原因。再来仔细分析下这个配置类 ErrorMvcAutoConfiguration

首先，我们ErrorMvcAutoConfiguration 为我们配置了这几个组件（@Bean）

DefaultErrorAttributes
BasicErrorController
ErrorPageCustomizer
DefaultErrorViewResolve

ErrorPageCustomizer

@Bean
	public ErrorPageCustomizer errorPageCustomizer(DispatcherServletPath dispatcherServletPath) {
		return new ErrorPageCustomizer(this.serverProperties, dispatcherServletPath);
	}

这个组件它会实例化出一个 ErrorPageCustomizer对象，在ErrorPageCustomizer对象中有一个重要的方法registerErrorPages

在ErrorMvcAutoConfiguration中有个静态内部类

private static class ErrorPageCustomizer implements ErrorPageRegistrar, Ordered {

		private final ServerProperties properties;

		private final DispatcherServletPath dispatcherServletPath;

		protected ErrorPageCustomizer(ServerProperties properties, DispatcherServletPath dispatcherServletPath) {
			this.properties = properties;
			this.dispatcherServletPath = dispatcherServletPath;
		}

		@Override
		public void registerErrorPages(ErrorPageRegistry errorPageRegistry) {
			ErrorPage errorPage = new ErrorPage(
					this.dispatcherServletPath.getRelativePath(this.properties.getError().getPath()));
			errorPageRegistry.addErrorPages(errorPage);
		}

		@Override
		public int getOrder() {
			return 0;
		}

	}

registerErrorPages方法会注册一个错误页面，通过 getPath()获取到路径，getPath存在默认的值为"/error"，如果在配置文件中配值了``server.error.path=/errors那就会从配置文件中取出error.path`的值，没有就会获取默认配置文件的配置/error

ErrorPageCustomizer组件的作用就是当用户请求一旦发生错误时，就会获得 path (错误页面的路径)，然后将我们转发到 path 路径下。并将该路径信息发给BasicErrorController 进行处理

basicErrorController就是默认的程序出错的controller

我们到springboot系统自动配置类中找到这个类找到其核心代码

@Override
	public String getErrorPath() {
		return this.errorProperties.getPath();
	}

	@RequestMapping(produces = MediaType.TEXT_HTML_VALUE)
	public ModelAndView errorHtml(HttpServletRequest request, HttpServletResponse response) {
		HttpStatus status = getStatus(request);
		Map<String, Object> model = Collections
				.unmodifiableMap(getErrorAttributes(request, isIncludeStackTrace(request, MediaType.TEXT_HTML)));
		response.setStatus(status.value());
		ModelAndView modelAndView = resolveErrorView(request, response, status, model);
		return (modelAndView != null) ? modelAndView : new ModelAndView("error", model);
	}

	@RequestMapping
	public ResponseEntity<Map<String, Object>> error(HttpServletRequest request) {
		HttpStatus status = getStatus(request);
		if (status == HttpStatus.NO_CONTENT) {
			return new ResponseEntity<>(status);
		}
		Map<String, Object> body = getErrorAttributes(request, isIncludeStackTrace(request, MediaType.ALL));
		return new ResponseEntity<>(body, status);
	}

它是用来处理配置文件下的 server.error.path的请求，如果 server.error.path 未配置时，就会处理配置文件下的 error.path的请求，如果也没配置，就会处理/error

在这个控制器组件下面存在着两个 @RequestMapping ，都是处理同一个请求路径的方法。只是这两个方法的返回值不一样

但是竟然这两种方式都是用于处理一个请求的，为什么浏览器获取的数据和postMan获取的会不一样呢？

原因是浏览器发送的请求的请求头包含这串信息

Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9

也就是说浏览器优先接收 text/html类型的数据，也就是第一个@RequestMapping那个

而postMan发送请求时的请求头如下，它没有指明希望接收的数据类型，所以服务端给它返回一个JSON类型的数据

那重点来了，返回页面时，又是如何实现的呢？

	@RequestMapping(produces = MediaType.TEXT_HTML_VALUE) // TEXT_HTML_VALUE = "text/html
	public ModelAndView errorHtml(HttpServletRequest request, HttpServletResponse response) {
		HttpStatus status = getStatus(request);
		Map<String, Object> model = Collections
				.unmodifiableMap(getErrorAttributes(request, isIncludeStackTrace(request, MediaType.TEXT_HTML)));
		response.setStatus(status.value());
		ModelAndView modelAndView = resolveErrorView(request, response, status, model);
		return (modelAndView != null) ? modelAndView : new ModelAndView("error", model);
	}

当用户发送请求，发送错误时

首先，它会通过请求获取响应状态码和一些model数据，，然后返回一个 modelAndViews ，通过第7行，我们可以知道 modelAndViews 是通过调用 resolveErrorView() 方法获得的。modelAndViews 包含了需要返回的地址，页面等信息
响应页面是调用了 resolveErrorView() ，如下

protected ModelAndView resolveErrorView(HttpServletRequest request, HttpServletResponse response, HttpStatus status,Map<String, Object> model) {
    for (ErrorViewResolver resolver : this.errorViewResolvers) {
	   ModelAndView modelAndView = resolver.resolveErrorView(request, status, model);
		if (modelAndView != null) {
			return modelAndView;
		}
	}
	return null;
}

第2行：遍历所有的 ErrorViewResolver ，调用resolver. resolveErrorView(request, status, model) 如果存在着一个 modelAndView 就返回.

在之前，Spring Boot 为我们自动注册了一个 DefaultErrorViewResolver 到容器中，也就是说resolveErrorView() 方法将会由 DefaultErrorViewResolver 进行调用。

DefaultErrorViewResolver

按照该类的描述，这个类是全局的错误控制器，渲染出现的错误的属性。也可以@ExceptionHandler指定异常处理或者添加对应的服务器错误页面实现跳转

BasicErrorController中有一个属性ErrorProperties

/*
 * Copyright 2012-2019 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.boot.autoconfigure.web;

import org.springframework.beans.factory.annotation.Value;

/**
 * Configuration properties for web error handling.
 *
 * @author Michael Stummvoll
 * @author Stephane Nicoll
 * @author Vedran Pavic
 * @since 1.3.0
 */
public class ErrorProperties {

	/**
	 * Path of the error controller.
	 */
	@Value("${error.path:/error}")
	private String path = "/error";

	/**
	 * Include the "exception" attribute.
	 */
	private boolean includeException;

	/**
	 * When to include a "stacktrace" attribute.
	 */
	private IncludeStacktrace includeStacktrace = IncludeStacktrace.NEVER;

	private final Whitelabel whitelabel = new Whitelabel();

	public String getPath() {
		return this.path;
	}

	public void setPath(String path) {
		this.path = path;
	}

	public boolean isIncludeException() {
		return this.includeException;
	}

	public void setIncludeException(boolean includeException) {
		this.includeException = includeException;
	}

	public IncludeStacktrace getIncludeStacktrace() {
		return this.includeStacktrace;
	}

	public void setIncludeStacktrace(IncludeStacktrace includeStacktrace) {
		this.includeStacktrace = includeStacktrace;
	}

	public Whitelabel getWhitelabel() {
		return this.whitelabel;
	}

	/**
	 * Include Stacktrace attribute options.
	 */
	public enum IncludeStacktrace {

		/**
		 * Never add stacktrace information.
		 */
		NEVER,

		/**
		 * Always add stacktrace information.
		 */
		ALWAYS,

		/**
		 * Add stacktrace information when the "trace" request parameter is "true".
		 */
		ON_TRACE_PARAM

	}

	public static class Whitelabel {

		/**
		 * Whether to enable the default error page displayed in browsers in case of a
		 * server error.
		 */
		private boolean enabled = true;

		public boolean isEnabled() {
			return this.enabled;
		}

		public void setEnabled(boolean enabled) {
			this.enabled = enabled;
		}

	}

}

定义了图一的错误信息，同时 BasicErrorController extends AbstractErrorController

@RequestMapping("${server.error.path:${error.path:/error}}")代表使用的配置文件的地址

https://docs.spring.io/spring-boot/docs/current/reference/html/appendix-application-properties.html#common-application-properties-server

定义了application.properties文件的默认属性，如果未定义，则使用的默认的上方的/error

再来看一下BasicErrorController ，其中有2个构造器，属性

errorAttributes:Provides access to error attributes which can be logged or presented to the user.

/*
 * Copyright 2012-2019 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.boot.web.servlet.error;

import java.util.Map;

import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.context.request.WebRequest;
import org.springframework.web.servlet.ModelAndView;

/**
 * Provides access to error attributes which can be logged or presented to the user.
 *
 * @author Phillip Webb
 * @since 2.0.0
 * @see DefaultErrorAttributes
 */
public interface ErrorAttributes {

	/**
	 * Returns a {@link Map} of the error attributes. The map can be used as the model of
	 * an error page {@link ModelAndView}, or returned as a
	 * {@link ResponseBody @ResponseBody}.
	 * @param webRequest the source request
	 * @param includeStackTrace if stack trace elements should be included
	 * @return a map of error attributes
	 */
	Map<String, Object> getErrorAttributes(WebRequest webRequest, boolean includeStackTrace);

	/**
	 * Return the underlying cause of the error or {@code null} if the error cannot be
	 * extracted.
	 * @param webRequest the source request
	 * @return the {@link Exception} that caused the error or {@code null}
	 */
	Throwable getError(WebRequest webRequest);

}

使用webRequest和堆栈信息，返回一个错误属性的有序map
getErrorAttributes(WebRequest webRequest,boolean includeStackTrace)的实现方法

@Override
	public Map<String, Object> getErrorAttributes(WebRequest webRequest, boolean includeStackTrace) {
		Map<String, Object> errorAttributes = new LinkedHashMap<>();
		errorAttributes.put("timestamp", new Date());
		addStatus(errorAttributes, webRequest);
		addErrorDetails(errorAttributes, webRequest, includeStackTrace);
		addPath(errorAttributes, webRequest);
		return errorAttributes;
	}

errorProperties:

errorViewResolvers

码农公寓

1：页面呈现

2：原理分析

ErrorPageCustomizer

DefaultErrorViewResolver

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