Spring 源码解析十四：SpringBoot Autoconfigure 初始化应用时加载的组件

这些组件定义在 spring.factories 中

# 初始化器
org.springframework.context.ApplicationContextInitializer=\
org.springframework.boot.autoconfigure.SharedMetadataReaderFactoryContextInitializer,\
org.springframework.boot.autoconfigure.logging.ConditionEvaluationReportLoggingListener

# 应用事件监听器
org.springframework.context.ApplicationListener=\
org.springframework.boot.autoconfigure.BackgroundPreinitializer

# 自动配置导入监听器
org.springframework.boot.autoconfigure.AutoConfigurationImportListener=\
org.springframework.boot.autoconfigure.condition.ConditionEvaluationReportAutoConfigurationImportListener

# 自动配置导入过滤器
org.springframework.boot.autoconfigure.AutoConfigurationImportFilter=\
org.springframework.boot.autoconfigure.condition.OnBeanCondition,\
org.springframework.boot.autoconfigure.condition.OnClassCondition,\
org.springframework.boot.autoconfigure.condition.OnWebApplicationCondition

# 自动配置
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
org.springframework.boot.autoconfigure.admin.SpringApplicationAdminJmxAutoConfiguration,\
org.springframework.boot.autoconfigure.aop.AopAutoConfiguration,\
org.springframework.boot.autoconfigure.amqp.RabbitAutoConfiguration,\
org.springframework.boot.autoconfigure.batch.BatchAutoConfiguration,\
org.springframework.boot.autoconfigure.cache.CacheAutoConfiguration,\
org.springframework.boot.autoconfigure.cassandra.CassandraAutoConfiguration,\
org.springframework.boot.autoconfigure.context.ConfigurationPropertiesAutoConfiguration,\
org.springframework.boot.autoconfigure.context.LifecycleAutoConfiguration,\
org.springframework.boot.autoconfigure.context.MessageSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.context.PropertyPlaceholderAutoConfiguration,\
org.springframework.boot.autoconfigure.couchbase.CouchbaseAutoConfiguration,\
org.springframework.boot.autoconfigure.dao.PersistenceExceptionTranslationAutoConfiguration,\
org.springframework.boot.autoconfigure.data.cassandra.CassandraDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.cassandra.CassandraReactiveDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.cassandra.CassandraReactiveRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.cassandra.CassandraRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.couchbase.CouchbaseDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.couchbase.CouchbaseReactiveDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.couchbase.CouchbaseReactiveRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.couchbase.CouchbaseRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.elasticsearch.ReactiveElasticsearchRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.elasticsearch.ReactiveElasticsearchRestClientAutoConfiguration,\
org.springframework.boot.autoconfigure.data.jdbc.JdbcRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.jpa.JpaRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.ldap.LdapRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.mongo.MongoDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.mongo.MongoReactiveDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.mongo.MongoReactiveRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.mongo.MongoRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.neo4j.Neo4jDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.neo4j.Neo4jReactiveDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.neo4j.Neo4jReactiveRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.neo4j.Neo4jRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.r2dbc.R2dbcDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.r2dbc.R2dbcRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.redis.RedisAutoConfiguration,\
org.springframework.boot.autoconfigure.data.redis.RedisReactiveAutoConfiguration,\
org.springframework.boot.autoconfigure.data.redis.RedisRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.rest.RepositoryRestMvcAutoConfiguration,\
org.springframework.boot.autoconfigure.data.web.SpringDataWebAutoConfiguration,\
org.springframework.boot.autoconfigure.elasticsearch.ElasticsearchRestClientAutoConfiguration,\
org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration,\
org.springframework.boot.autoconfigure.freemarker.FreeMarkerAutoConfiguration,\
org.springframework.boot.autoconfigure.groovy.template.GroovyTemplateAutoConfiguration,\
org.springframework.boot.autoconfigure.gson.GsonAutoConfiguration,\
org.springframework.boot.autoconfigure.h2.H2ConsoleAutoConfiguration,\
org.springframework.boot.autoconfigure.hateoas.HypermediaAutoConfiguration,\
org.springframework.boot.autoconfigure.hazelcast.HazelcastAutoConfiguration,\
org.springframework.boot.autoconfigure.hazelcast.HazelcastJpaDependencyAutoConfiguration,\
org.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfiguration,\
org.springframework.boot.autoconfigure.http.codec.CodecsAutoConfiguration,\
org.springframework.boot.autoconfigure.influx.InfluxDbAutoConfiguration,\
org.springframework.boot.autoconfigure.info.ProjectInfoAutoConfiguration,\
org.springframework.boot.autoconfigure.integration.IntegrationAutoConfiguration,\
org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.JdbcTemplateAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.JndiDataSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.XADataSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration,\
org.springframework.boot.autoconfigure.jms.JmsAutoConfiguration,\
org.springframework.boot.autoconfigure.jmx.JmxAutoConfiguration,\
org.springframework.boot.autoconfigure.jms.JndiConnectionFactoryAutoConfiguration,\
org.springframework.boot.autoconfigure.jms.activemq.ActiveMQAutoConfiguration,\
org.springframework.boot.autoconfigure.jms.artemis.ArtemisAutoConfiguration,\
org.springframework.boot.autoconfigure.jersey.JerseyAutoConfiguration,\
org.springframework.boot.autoconfigure.jooq.JooqAutoConfiguration,\
org.springframework.boot.autoconfigure.jsonb.JsonbAutoConfiguration,\
org.springframework.boot.autoconfigure.kafka.KafkaAutoConfiguration,\
org.springframework.boot.autoconfigure.availability.ApplicationAvailabilityAutoConfiguration,\
org.springframework.boot.autoconfigure.ldap.embedded.EmbeddedLdapAutoConfiguration,\
org.springframework.boot.autoconfigure.ldap.LdapAutoConfiguration,\
org.springframework.boot.autoconfigure.liquibase.LiquibaseAutoConfiguration,\
org.springframework.boot.autoconfigure.mail.MailSenderAutoConfiguration,\
org.springframework.boot.autoconfigure.mail.MailSenderValidatorAutoConfiguration,\
org.springframework.boot.autoconfigure.mongo.embedded.EmbeddedMongoAutoConfiguration,\
org.springframework.boot.autoconfigure.mongo.MongoAutoConfiguration,\
org.springframework.boot.autoconfigure.mongo.MongoReactiveAutoConfiguration,\
org.springframework.boot.autoconfigure.mustache.MustacheAutoConfiguration,\
org.springframework.boot.autoconfigure.neo4j.Neo4jAutoConfiguration,\
org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration,\
org.springframework.boot.autoconfigure.quartz.QuartzAutoConfiguration,\
org.springframework.boot.autoconfigure.r2dbc.R2dbcAutoConfiguration,\
org.springframework.boot.autoconfigure.r2dbc.R2dbcTransactionManagerAutoConfiguration,\
org.springframework.boot.autoconfigure.rsocket.RSocketMessagingAutoConfiguration,\
org.springframework.boot.autoconfigure.rsocket.RSocketRequesterAutoConfiguration,\
org.springframework.boot.autoconfigure.rsocket.RSocketServerAutoConfiguration,\
org.springframework.boot.autoconfigure.rsocket.RSocketStrategiesAutoConfiguration,\
org.springframework.boot.autoconfigure.security.servlet.SecurityAutoConfiguration,\
org.springframework.boot.autoconfigure.security.servlet.UserDetailsServiceAutoConfiguration,\
org.springframework.boot.autoconfigure.security.servlet.SecurityFilterAutoConfiguration,\
org.springframework.boot.autoconfigure.security.reactive.ReactiveSecurityAutoConfiguration,\
org.springframework.boot.autoconfigure.security.reactive.ReactiveUserDetailsServiceAutoConfiguration,\
org.springframework.boot.autoconfigure.security.rsocket.RSocketSecurityAutoConfiguration,\
org.springframework.boot.autoconfigure.security.saml2.Saml2RelyingPartyAutoConfiguration,\
org.springframework.boot.autoconfigure.sendgrid.SendGridAutoConfiguration,\
org.springframework.boot.autoconfigure.session.SessionAutoConfiguration,\
org.springframework.boot.autoconfigure.security.oauth2.client.servlet.OAuth2ClientAutoConfiguration,\
org.springframework.boot.autoconfigure.security.oauth2.client.reactive.ReactiveOAuth2ClientAutoConfiguration,\
org.springframework.boot.autoconfigure.security.oauth2.resource.servlet.OAuth2ResourceServerAutoConfiguration,\
org.springframework.boot.autoconfigure.security.oauth2.resource.reactive.ReactiveOAuth2ResourceServerAutoConfiguration,\
org.springframework.boot.autoconfigure.solr.SolrAutoConfiguration,\
org.springframework.boot.autoconfigure.task.TaskExecutionAutoConfiguration,\
org.springframework.boot.autoconfigure.task.TaskSchedulingAutoConfiguration,\
org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration,\
org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration,\
org.springframework.boot.autoconfigure.transaction.jta.JtaAutoConfiguration,\
org.springframework.boot.autoconfigure.validation.ValidationAutoConfiguration,\
org.springframework.boot.autoconfigure.web.client.RestTemplateAutoConfiguration,\
org.springframework.boot.autoconfigure.web.embedded.EmbeddedWebServerFactoryCustomizerAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.HttpHandlerAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.ReactiveWebServerFactoryAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.WebFluxAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.error.ErrorWebFluxAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.function.client.ClientHttpConnectorAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.function.client.WebClientAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.DispatcherServletAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.ServletWebServerFactoryAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.error.ErrorMvcAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.HttpEncodingAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.MultipartAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfiguration,\
org.springframework.boot.autoconfigure.websocket.reactive.WebSocketReactiveAutoConfiguration,\
org.springframework.boot.autoconfigure.websocket.servlet.WebSocketServletAutoConfiguration,\
org.springframework.boot.autoconfigure.websocket.servlet.WebSocketMessagingAutoConfiguration,\
org.springframework.boot.autoconfigure.webservices.WebServicesAutoConfiguration,\
org.springframework.boot.autoconfigure.webservices.client.WebServiceTemplateAutoConfiguration

# 失败分析器
org.springframework.boot.diagnostics.FailureAnalyzer=\
org.springframework.boot.autoconfigure.data.redis.RedisUrlSyntaxFailureAnalyzer,\
org.springframework.boot.autoconfigure.diagnostics.analyzer.NoSuchBeanDefinitionFailureAnalyzer,\
org.springframework.boot.autoconfigure.flyway.FlywayMigrationScriptMissingFailureAnalyzer,\
org.springframework.boot.autoconfigure.jdbc.DataSourceBeanCreationFailureAnalyzer,\
org.springframework.boot.autoconfigure.jdbc.HikariDriverConfigurationFailureAnalyzer,\
org.springframework.boot.autoconfigure.r2dbc.ConnectionFactoryBeanCreationFailureAnalyzer,\
org.springframework.boot.autoconfigure.session.NonUniqueSessionRepositoryFailureAnalyzer

# 检查模板可用提供器
org.springframework.boot.autoconfigure.template.TemplateAvailabilityProvider=\
org.springframework.boot.autoconfigure.freemarker.FreeMarkerTemplateAvailabilityProvider,\
org.springframework.boot.autoconfigure.mustache.MustacheTemplateAvailabilityProvider,\
org.springframework.boot.autoconfigure.groovy.template.GroovyTemplateAvailabilityProvider,\
org.springframework.boot.autoconfigure.thymeleaf.ThymeleafTemplateAvailabilityProvider,\
org.springframework.boot.autoconfigure.web.servlet.JspTemplateAvailabilityProvider

1. 初始化器

org.springframework.context.ApplicationContextInitializer=\
org.springframework.boot.autoconfigure.SharedMetadataReaderFactoryContextInitializer,\
org.springframework.boot.autoconfigure.logging.ConditionEvaluationReportLoggingListener

1.1. SharedMetadataReaderFactoryContextInitializer

SharedMetadataReaderFactoryContextInitializer 的主要功能是提供一个共享的缓存元信息读取工厂

class SharedMetadataReaderFactoryContextInitializer
        implements ApplicationContextInitializer<ConfigurableApplicationContext>, Ordered {
    // 初始化
    @Override
    public void initialize(ConfigurableApplicationContext applicationContext) {
        BeanFactoryPostProcessor postProcessor = new CachingMetadataReaderFactoryPostProcessor(applicationContext);
        applicationContext.addBeanFactoryPostProcessor(postProcessor);
    }

    static class CachingMetadataReaderFactoryPostProcessor
            implements BeanDefinitionRegistryPostProcessor, PriorityOrdered {
        // 注册bean定义
        @Override
        public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
            // 注册bean定义注册器
            register(registry);
            // 配置 @Configuration bean
            configureConfigurationClassPostProcessor(registry);
        }

        // 注册bean定义注册器
        private void register(BeanDefinitionRegistry registry) {
            BeanDefinition definition = BeanDefinitionBuilder
                    .genericBeanDefinition(SharedMetadataReaderFactoryBean.class, SharedMetadataReaderFactoryBean::new)
                    .getBeanDefinition();
            // 注册为 "org.springframework.boot.autoconfigure.internalCachingMetadataReaderFactory" 名字
            registry.registerBeanDefinition(BEAN_NAME, definition);
        }

        // 配置 @Configuration bean
        private void configureConfigurationClassPostProcessor(BeanDefinitionRegistry registry) {
            try {
                // 配置bean "org.springframework.context.annotation.internalConfigurationAnnotationProcessor"
                configureConfigurationClassPostProcessor(
                        registry.getBeanDefinition(AnnotationConfigUtils.CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME));
            }
            catch (NoSuchBeanDefinitionException ex) {
            }
        }
    }
}

1.2. ConditionEvaluationReportLoggingListener

ConditionEvaluationReportLoggingListener 的主要功能是输出日志到文件

2. 应用事件监听器

org.springframework.context.ApplicationListener=\
org.springframework.boot.autoconfigure.BackgroundPreinitializer

BackgroundPreinitializer 的主要功能是初始化数据转换与编码等服务

public class BackgroundPreinitializer implements ApplicationListener<SpringApplicationEvent> {
    @Override
    public void onApplicationEvent(SpringApplicationEvent event) {
        // ... 代码省略

        if (event instanceof ApplicationEnvironmentPreparedEvent
                && preinitializationStarted.compareAndSet(false, true)) {
            performPreinitialization();
        }
        if ((event instanceof ApplicationReadyEvent || event instanceof ApplicationFailedEvent)
                && preinitializationStarted.get()) {
            try {
                preinitializationComplete.await();
            }
            catch (InterruptedException ex) {
                Thread.currentThread().interrupt();
            }
        }
    }

    // 初始化其他组件
    private void performPreinitialization() {
        try {
            Thread thread = new Thread(new Runnable() {

                @Override
                public void run() {
                    // 初始化数据转换服务，DefaultFormattingConversionService
                    runSafely(new ConversionServiceInitializer());
                    // 初始化数据验证服务，Validation.byDefaultProvider()
                    runSafely(new ValidationInitializer());
                    // 初始化消息转换服务，AllEncompassingFormHttpMessageConverter
                    runSafely(new MessageConverterInitializer());
                    // 初始化JSON服务，Jackson2ObjectMapperBuilder
                    runSafely(new JacksonInitializer());
                    // 初始化字符编码服务，StandardCharsets
                    runSafely(new CharsetInitializer());
                    preinitializationComplete.countDown();
                }

                public void runSafely(Runnable runnable) {
                    try {
                        runnable.run();
                    }
                    catch (Throwable ex) {}
                }

            }, "background-preinit");
            thread.start();
        }
        catch (Exception ex) {
            // ... 代码省略
        }
    }

    private static class MessageConverterInitializer implements Runnable {
        @Override
        public void run() {
            new AllEncompassingFormHttpMessageConverter();
        }
    }

    private static class ValidationInitializer implements Runnable {
        @Override
        public void run() {
            Configuration<?> configuration = Validation.byDefaultProvider().configure();
            configuration.buildValidatorFactory().getValidator();
        }
    }

    private static class JacksonInitializer implements Runnable {
        @Override
        public void run() {
            Jackson2ObjectMapperBuilder.json().build();
        }
    }

    private static class ConversionServiceInitializer implements Runnable {
        @Override
        public void run() {
            new DefaultFormattingConversionService();
        }
    }

    private static class CharsetInitializer implements Runnable {
        @Override
        public void run() {
            StandardCharsets.UTF_8.name();
        }
    }
}

3. 自动配置导入监听器

org.springframework.boot.autoconfigure.AutoConfigurationImportListener=\
org.springframework.boot.autoconfigure.condition.ConditionEvaluationReportAutoConfigurationImportListener

ConditionEvaluationReportAutoConfigurationImportListener 的主要功能是从 Report 中读取结果

4. 自动配置导入过滤器

org.springframework.boot.autoconfigure.AutoConfigurationImportFilter=\
org.springframework.boot.autoconfigure.condition.OnBeanCondition,\
org.springframework.boot.autoconfigure.condition.OnClassCondition,\
org.springframework.boot.autoconfigure.condition.OnWebApplicationCondition

4.1. OnBeanCondition

OnBeanCondition 的主要功能是处理注解 @ConditionalOnBean、@ConditionalOnMissingBean、@ConditionalOnSingleCandidate，按条件动态载入 bean

@ConditionOnBean 判断条件 bean 存在，注入当下注解的 bean
@ConditionOnMissingBean 判断条件 bean 不存在，才注入当下注解的 bean
@ConditionalOnSingleCandidate 判断条件 bean 只能有一个实例或多个但只有一个 primary 实例，才注入当下注解的 bean

先来看看继承关系

- SpringBootCondition
  - FilteringSpringBootCondition
    - OnBeanCondition

4.1.1. SpringBootCondition

SpringBootCondition 是用条件来检查组件的基础类

public abstract class SpringBootCondition implements Condition {
    // 元信息代表的组件是否匹配
    @Override
    public final boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
        // 获取类名或方法名
        String classOrMethodName = getClassOrMethodName(metadata);
        try {
            // 获取匹配结果
            ConditionOutcome outcome = getMatchOutcome(context, metadata);

            // ... 代码省略

            // 返回是否匹配
            return outcome.isMatch();
        }
        catch (NoClassDefFoundError ex) {
            // ... 代码省略
        }

        // ... 代码省略
    }

    // 获取匹配结果，由子类实现
    public abstract ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata);
}

4.1.2. FilteringSpringBootCondition

FilteringSpringBootCondition 的主要功能是添加过滤功能

abstract class FilteringSpringBootCondition extends SpringBootCondition
        implements AutoConfigurationImportFilter, BeanFactoryAware, BeanClassLoaderAware {
    // 元信息代表的组件是否匹配
    @Override
    public boolean[] match(String[] autoConfigurationClasses, AutoConfigurationMetadata autoConfigurationMetadata) {
        // 获取结果
        ConditionOutcome[] outcomes = getOutcomes(autoConfigurationClasses, autoConfigurationMetadata);
        boolean[] match = new boolean[outcomes.length];
        for (int i = 0; i < outcomes.length; i++) {
            // 如果返回为null或true，则表示匹配
            match[i] = (outcomes[i] == null || outcomes[i].isMatch());
            // ... 代码省略
        }
        return match;
    }

    // 获取结果，由子类实现
    protected abstract ConditionOutcome[] getOutcomes(String[] autoConfigurationClasses,
            AutoConfigurationMetadata autoConfigurationMetadata);
}

4.1.3. SpringBootCondition

SpringBootCondition 的主要功能是处理注解 @ConditionalOnBean、@ConditionalOnMissingBean、@ConditionalOnSingleCandidate，按条件动态载入 bean

class OnBeanCondition extends FilteringSpringBootCondition implements ConfigurationCondition {
    // 获取结果
    @Override
    protected final ConditionOutcome[] getOutcomes(String[] autoConfigurationClasses,
            AutoConfigurationMetadata autoConfigurationMetadata) {
        // 结果集
        ConditionOutcome[] outcomes = new ConditionOutcome[autoConfigurationClasses.length];
        for (int i = 0; i < outcomes.length; i++) {
            // 自动配置类
            String autoConfigurationClass = autoConfigurationClasses[i];
            if (autoConfigurationClass != null) {
                // 获取ConditionalOnBean的bean类型
                Set<String> onBeanTypes = autoConfigurationMetadata.getSet(autoConfigurationClass, "ConditionalOnBean");
                // 确定有没有ConditionalOnBean的bean类型
                outcomes[i] = getOutcome(onBeanTypes, ConditionalOnBean.class);
                if (outcomes[i] == null) {
                    // 获取ConditionalOnSingleCandidate的bean类型
                    Set<String> onSingleCandidateTypes = autoConfigurationMetadata.getSet(autoConfigurationClass,
                            "ConditionalOnSingleCandidate");
                    // 确定有没有ConditionalOnSingleCandidate的bean类型
                    outcomes[i] = getOutcome(onSingleCandidateTypes, ConditionalOnSingleCandidate.class);
                }
            }
        }
        return outcomes;
    }
}

class OnBeanCondition extends FilteringSpringBootCondition implements ConfigurationCondition {
    // 获取匹配结果
    @Override
    public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {
        // 匹配信息
        ConditionMessage matchMessage = ConditionMessage.empty();
        // 元信息中的注解
        MergedAnnotations annotations = metadata.getAnnotations();
        // 有@ConditionalOnBean注解
        if (annotations.isPresent(ConditionalOnBean.class)) {
            // 创建ConditionalOnBean的匹配标准对象
            Spec<ConditionalOnBean> spec = new Spec<>(context, metadata, annotations, ConditionalOnBean.class);
            // 获取匹配的bean
            MatchResult matchResult = getMatchingBeans(context, spec);
            // 如果一个都没有匹配到
            if (!matchResult.isAllMatched()) {
                // 返回匹配不到的信息
                String reason = createOnBeanNoMatchReason(matchResult);
                return ConditionOutcome.noMatch(spec.message().because(reason));
            }
            // 匹配到了，继续
            matchMessage = spec.message(matchMessage).found("bean", "beans").items(Style.QUOTE,
                    matchResult.getNamesOfAllMatches());
        }
        // 有@ConditionalOnSingleCandidate注解
        if (metadata.isAnnotated(ConditionalOnSingleCandidate.class.getName())) {
            // 创建ConditionalOnSingleCandidate的匹配标准对象
            Spec<ConditionalOnSingleCandidate> spec = new SingleCandidateSpec(context, metadata, annotations);
            // 获取匹配的bean
            MatchResult matchResult = getMatchingBeans(context, spec);
            // 如果一个都没有匹配到
            if (!matchResult.isAllMatched()) {
                // 返回匹配不到的信息
                return ConditionOutcome.noMatch(spec.message().didNotFind("any beans").atAll());
            }
            // 匹配到多个bean，但没有primary bean
            else if (!hasSingleAutowireCandidate(context.getBeanFactory(), matchResult.getNamesOfAllMatches(),
                    spec.getStrategy() == SearchStrategy.ALL)) {
                // 返回匹配到多个的信息
                return ConditionOutcome.noMatch(spec.message().didNotFind("a primary bean from beans")
                        .items(Style.QUOTE, matchResult.getNamesOfAllMatches()));
            }
            // 匹配到了，继续
            matchMessage = spec.message(matchMessage).found("a primary bean from beans").items(Style.QUOTE,
                    matchResult.getNamesOfAllMatches());
        }
        // 有@ConditionalOnMissingBean注解
        if (metadata.isAnnotated(ConditionalOnMissingBean.class.getName())) {
            // 创建ConditionalOnMissingBean的匹配标准对象
            Spec<ConditionalOnMissingBean> spec = new Spec<>(context, metadata, annotations,
                    ConditionalOnMissingBean.class);
            // 获取匹配的bean
            MatchResult matchResult = getMatchingBeans(context, spec);
            // 如果匹配到了
            if (matchResult.isAnyMatched()) {
                // 返回匹配到了的信息
                String reason = createOnMissingBeanNoMatchReason(matchResult);
                return ConditionOutcome.noMatch(spec.message().because(reason));
            }
            // 匹配不到，继续
            matchMessage = spec.message(matchMessage).didNotFind("any beans").atAll();
        }
        return ConditionOutcome.match(matchMessage);
    }
}

4.2. OnClassCondition

OnClassCondition 的主要功能是处理注解 @ConditionalOnClass、@ConditionalOnMissingClass，按条件动态载入 bean

@ConditionalOnClass 判断条件类存在，注入当下注解的 bean
@ConditionalOnMissingClass 判断条件类不存在，才注入当下注解的 bean

class OnClassCondition extends FilteringSpringBootCondition {
    // 获取结果
    @Override
    protected final ConditionOutcome[] getOutcomes(String[] autoConfigurationClasses,
            AutoConfigurationMetadata autoConfigurationMetadata) {
        // ... 代码省略

        OutcomesResolver outcomesResolver = new StandardOutcomesResolver(autoConfigurationClasses, 0,
                autoConfigurationClasses.length, autoConfigurationMetadata, getBeanClassLoader());
        // 获取ConditionalOnClass的输出
        return outcomesResolver.resolveOutcomes();

    }

    // 获取匹配结果
    @Override
    public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {
        ClassLoader classLoader = context.getClassLoader();
        // 匹配信息
        ConditionMessage matchMessage = ConditionMessage.empty();
        // 获取标记有@ConditionalOnClass注解的类
        List<String> onClasses = getCandidates(metadata, ConditionalOnClass.class);
        if (onClasses != null) {
            List<String> missing = filter(onClasses, ClassNameFilter.MISSING, classLoader);
            // 类不存在，返回
            if (!missing.isEmpty()) {
                return ConditionOutcome.noMatch(ConditionMessage.forCondition(ConditionalOnClass.class)
                        .didNotFind("required class", "required classes").items(Style.QUOTE, missing));
            }
            // 类存在，继续
            matchMessage = matchMessage.andCondition(ConditionalOnClass.class)
                    .found("required class", "required classes")
                    .items(Style.QUOTE, filter(onClasses, ClassNameFilter.PRESENT, classLoader));
        }
        // 获取标记有@ConditionalOnMissingClass注解的类
        List<String> onMissingClasses = getCandidates(metadata, ConditionalOnMissingClass.class);
        if (onMissingClasses != null) {
            List<String> present = filter(onMissingClasses, ClassNameFilter.PRESENT, classLoader);
            // 类存在，返回
            if (!present.isEmpty()) {
                return ConditionOutcome.noMatch(ConditionMessage.forCondition(ConditionalOnMissingClass.class)
                        .found("unwanted class", "unwanted classes").items(Style.QUOTE, present));
            }
            // 类不存在，继续
            matchMessage = matchMessage.andCondition(ConditionalOnMissingClass.class)
                    .didNotFind("unwanted class", "unwanted classes")
                    .items(Style.QUOTE, filter(onMissingClasses, ClassNameFilter.MISSING, classLoader));
        }
        return ConditionOutcome.match(matchMessage);
    }

}

4.3. OnWebApplicationCondition

OnWebApplicationCondition 的主要功能是处理注解 @ConditionalOnWebApplication、@ConditionalOnNotWebApplication，按条件动态载入 bean

@ConditionalOnWebApplication 判断应用时 Web 应用时，注入当下注解的 bean
@ConditionalOnNotWebApplication 判断应用时不是 Web 应用时，才注入当下注解的 bean

5. 自动配置

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
org.springframework.boot.autoconfigure.admin.SpringApplicationAdminJmxAutoConfiguration,\
org.springframework.boot.autoconfigure.aop.AopAutoConfiguration,\
org.springframework.boot.autoconfigure.amqp.RabbitAutoConfiguration,\
org.springframework.boot.autoconfigure.batch.BatchAutoConfiguration,\
org.springframework.boot.autoconfigure.cache.CacheAutoConfiguration,\
org.springframework.boot.autoconfigure.cassandra.CassandraAutoConfiguration,\
org.springframework.boot.autoconfigure.context.ConfigurationPropertiesAutoConfiguration,\
org.springframework.boot.autoconfigure.context.LifecycleAutoConfiguration,\
org.springframework.boot.autoconfigure.context.MessageSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.context.PropertyPlaceholderAutoConfiguration,\
org.springframework.boot.autoconfigure.couchbase.CouchbaseAutoConfiguration,\
org.springframework.boot.autoconfigure.dao.PersistenceExceptionTranslationAutoConfiguration,\
org.springframework.boot.autoconfigure.data.cassandra.CassandraDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.cassandra.CassandraReactiveDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.cassandra.CassandraReactiveRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.cassandra.CassandraRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.couchbase.CouchbaseDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.couchbase.CouchbaseReactiveDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.couchbase.CouchbaseReactiveRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.couchbase.CouchbaseRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.elasticsearch.ElasticsearchRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.elasticsearch.ReactiveElasticsearchRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.elasticsearch.ReactiveElasticsearchRestClientAutoConfiguration,\
org.springframework.boot.autoconfigure.data.jdbc.JdbcRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.jpa.JpaRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.ldap.LdapRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.mongo.MongoDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.mongo.MongoReactiveDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.mongo.MongoReactiveRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.mongo.MongoRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.neo4j.Neo4jDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.neo4j.Neo4jReactiveDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.neo4j.Neo4jReactiveRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.neo4j.Neo4jRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.r2dbc.R2dbcDataAutoConfiguration,\
org.springframework.boot.autoconfigure.data.r2dbc.R2dbcRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.redis.RedisAutoConfiguration,\
org.springframework.boot.autoconfigure.data.redis.RedisReactiveAutoConfiguration,\
org.springframework.boot.autoconfigure.data.redis.RedisRepositoriesAutoConfiguration,\
org.springframework.boot.autoconfigure.data.rest.RepositoryRestMvcAutoConfiguration,\
org.springframework.boot.autoconfigure.data.web.SpringDataWebAutoConfiguration,\
org.springframework.boot.autoconfigure.elasticsearch.ElasticsearchRestClientAutoConfiguration,\
org.springframework.boot.autoconfigure.flyway.FlywayAutoConfiguration,\
org.springframework.boot.autoconfigure.freemarker.FreeMarkerAutoConfiguration,\
org.springframework.boot.autoconfigure.groovy.template.GroovyTemplateAutoConfiguration,\
org.springframework.boot.autoconfigure.gson.GsonAutoConfiguration,\
org.springframework.boot.autoconfigure.h2.H2ConsoleAutoConfiguration,\
org.springframework.boot.autoconfigure.hateoas.HypermediaAutoConfiguration,\
org.springframework.boot.autoconfigure.hazelcast.HazelcastAutoConfiguration,\
org.springframework.boot.autoconfigure.hazelcast.HazelcastJpaDependencyAutoConfiguration,\
org.springframework.boot.autoconfigure.http.HttpMessageConvertersAutoConfiguration,\
org.springframework.boot.autoconfigure.http.codec.CodecsAutoConfiguration,\
org.springframework.boot.autoconfigure.influx.InfluxDbAutoConfiguration,\
org.springframework.boot.autoconfigure.info.ProjectInfoAutoConfiguration,\
org.springframework.boot.autoconfigure.integration.IntegrationAutoConfiguration,\
org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.JdbcTemplateAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.JndiDataSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.XADataSourceAutoConfiguration,\
org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration,\
org.springframework.boot.autoconfigure.jms.JmsAutoConfiguration,\
org.springframework.boot.autoconfigure.jmx.JmxAutoConfiguration,\
org.springframework.boot.autoconfigure.jms.JndiConnectionFactoryAutoConfiguration,\
org.springframework.boot.autoconfigure.jms.activemq.ActiveMQAutoConfiguration,\
org.springframework.boot.autoconfigure.jms.artemis.ArtemisAutoConfiguration,\
org.springframework.boot.autoconfigure.jersey.JerseyAutoConfiguration,\
org.springframework.boot.autoconfigure.jooq.JooqAutoConfiguration,\
org.springframework.boot.autoconfigure.jsonb.JsonbAutoConfiguration,\
org.springframework.boot.autoconfigure.kafka.KafkaAutoConfiguration,\
org.springframework.boot.autoconfigure.availability.ApplicationAvailabilityAutoConfiguration,\
org.springframework.boot.autoconfigure.ldap.embedded.EmbeddedLdapAutoConfiguration,\
org.springframework.boot.autoconfigure.ldap.LdapAutoConfiguration,\
org.springframework.boot.autoconfigure.liquibase.LiquibaseAutoConfiguration,\
org.springframework.boot.autoconfigure.mail.MailSenderAutoConfiguration,\
org.springframework.boot.autoconfigure.mail.MailSenderValidatorAutoConfiguration,\
org.springframework.boot.autoconfigure.mongo.embedded.EmbeddedMongoAutoConfiguration,\
org.springframework.boot.autoconfigure.mongo.MongoAutoConfiguration,\
org.springframework.boot.autoconfigure.mongo.MongoReactiveAutoConfiguration,\
org.springframework.boot.autoconfigure.mustache.MustacheAutoConfiguration,\
org.springframework.boot.autoconfigure.neo4j.Neo4jAutoConfiguration,\
org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration,\
org.springframework.boot.autoconfigure.quartz.QuartzAutoConfiguration,\
org.springframework.boot.autoconfigure.r2dbc.R2dbcAutoConfiguration,\
org.springframework.boot.autoconfigure.r2dbc.R2dbcTransactionManagerAutoConfiguration,\
org.springframework.boot.autoconfigure.rsocket.RSocketMessagingAutoConfiguration,\
org.springframework.boot.autoconfigure.rsocket.RSocketRequesterAutoConfiguration,\
org.springframework.boot.autoconfigure.rsocket.RSocketServerAutoConfiguration,\
org.springframework.boot.autoconfigure.rsocket.RSocketStrategiesAutoConfiguration,\
org.springframework.boot.autoconfigure.security.servlet.SecurityAutoConfiguration,\
org.springframework.boot.autoconfigure.security.servlet.UserDetailsServiceAutoConfiguration,\
org.springframework.boot.autoconfigure.security.servlet.SecurityFilterAutoConfiguration,\
org.springframework.boot.autoconfigure.security.reactive.ReactiveSecurityAutoConfiguration,\
org.springframework.boot.autoconfigure.security.reactive.ReactiveUserDetailsServiceAutoConfiguration,\
org.springframework.boot.autoconfigure.security.rsocket.RSocketSecurityAutoConfiguration,\
org.springframework.boot.autoconfigure.security.saml2.Saml2RelyingPartyAutoConfiguration,\
org.springframework.boot.autoconfigure.sendgrid.SendGridAutoConfiguration,\
org.springframework.boot.autoconfigure.session.SessionAutoConfiguration,\
org.springframework.boot.autoconfigure.security.oauth2.client.servlet.OAuth2ClientAutoConfiguration,\
org.springframework.boot.autoconfigure.security.oauth2.client.reactive.ReactiveOAuth2ClientAutoConfiguration,\
org.springframework.boot.autoconfigure.security.oauth2.resource.servlet.OAuth2ResourceServerAutoConfiguration,\
org.springframework.boot.autoconfigure.security.oauth2.resource.reactive.ReactiveOAuth2ResourceServerAutoConfiguration,\
org.springframework.boot.autoconfigure.solr.SolrAutoConfiguration,\
org.springframework.boot.autoconfigure.task.TaskExecutionAutoConfiguration,\
org.springframework.boot.autoconfigure.task.TaskSchedulingAutoConfiguration,\
org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration,\
org.springframework.boot.autoconfigure.transaction.TransactionAutoConfiguration,\
org.springframework.boot.autoconfigure.transaction.jta.JtaAutoConfiguration,\
org.springframework.boot.autoconfigure.validation.ValidationAutoConfiguration,\
org.springframework.boot.autoconfigure.web.client.RestTemplateAutoConfiguration,\
org.springframework.boot.autoconfigure.web.embedded.EmbeddedWebServerFactoryCustomizerAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.HttpHandlerAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.ReactiveWebServerFactoryAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.WebFluxAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.error.ErrorWebFluxAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.function.client.ClientHttpConnectorAutoConfiguration,\
org.springframework.boot.autoconfigure.web.reactive.function.client.WebClientAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.DispatcherServletAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.ServletWebServerFactoryAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.error.ErrorMvcAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.HttpEncodingAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.MultipartAutoConfiguration,\
org.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfiguration,\
org.springframework.boot.autoconfigure.websocket.reactive.WebSocketReactiveAutoConfiguration,\
org.springframework.boot.autoconfigure.websocket.servlet.WebSocketServletAutoConfiguration,\
org.springframework.boot.autoconfigure.websocket.servlet.WebSocketMessagingAutoConfiguration,\
org.springframework.boot.autoconfigure.webservices.WebServicesAutoConfiguration,\
org.springframework.boot.autoconfigure.webservices.client.WebServiceTemplateAutoConfiguration

SpringApplicationAdminJmxAutoConfiguration
AopAutoConfiguration
RabbitAutoConfiguration
BatchAutoConfiguration
CacheAutoConfiguration
CassandraAutoConfiguration
ConfigurationPropertiesAutoConfiguration
LifecycleAutoConfiguration
MessageSourceAutoConfiguration
PropertyPlaceholderAutoConfiguration
CouchbaseAutoConfiguration
PersistenceExceptionTranslationAutoConfiguration
CassandraDataAutoConfiguration
CassandraReactiveDataAutoConfiguration
CassandraReactiveRepositoriesAutoConfiguration
CassandraRepositoriesAutoConfiguration
CouchbaseDataAutoConfiguration
CouchbaseReactiveDataAutoConfiguration
CouchbaseReactiveRepositoriesAutoConfiguration
CouchbaseRepositoriesAutoConfiguration
ElasticsearchDataAutoConfiguration
ElasticsearchRepositoriesAutoConfiguration
ReactiveElasticsearchRepositoriesAutoConfiguration
ReactiveElasticsearchRestClientAutoConfiguration
JdbcRepositoriesAutoConfiguration
JpaRepositoriesAutoConfiguration
LdapRepositoriesAutoConfiguration
MongoDataAutoConfiguration
MongoReactiveDataAutoConfiguration
MongoReactiveRepositoriesAutoConfiguration
MongoRepositoriesAutoConfiguration
Neo4jDataAutoConfiguration
Neo4jReactiveDataAutoConfiguration
Neo4jReactiveRepositoriesAutoConfiguration
Neo4jRepositoriesAutoConfiguration
R2dbcDataAutoConfiguration
R2dbcRepositoriesAutoConfiguration
RedisAutoConfiguration
RedisReactiveAutoConfiguration
RedisRepositoriesAutoConfiguration
RepositoryRestMvcAutoConfiguration
SpringDataWebAutoConfiguration
ElasticsearchRestClientAutoConfiguration
FlywayAutoConfiguration
FreeMarkerAutoConfiguration
GroovyTemplateAutoConfiguration
GsonAutoConfiguration
H2ConsoleAutoConfiguration
HypermediaAutoConfiguration
HazelcastAutoConfiguration
HazelcastJpaDependencyAutoConfiguration
HttpMessageConvertersAutoConfiguration
CodecsAutoConfiguration
InfluxDbAutoConfiguration
ProjectInfoAutoConfiguration
IntegrationAutoConfiguration
JacksonAutoConfiguration
DataSourceAutoConfiguration
JdbcTemplateAutoConfiguration
JndiDataSourceAutoConfiguration
XADataSourceAutoConfiguration
DataSourceTransactionManagerAutoConfiguration
JmsAutoConfiguration
JmxAutoConfiguration
JndiConnectionFactoryAutoConfiguration
ActiveMQAutoConfiguration
ArtemisAutoConfiguration
JerseyAutoConfiguration
JooqAutoConfiguration
JsonbAutoConfiguration
KafkaAutoConfiguration
ApplicationAvailabilityAutoConfiguration
EmbeddedLdapAutoConfiguration
LdapAutoConfiguration
LiquibaseAutoConfiguration
MailSenderAutoConfiguration
MailSenderValidatorAutoConfiguration
EmbeddedMongoAutoConfiguration
MongoAutoConfiguration
MongoReactiveAutoConfiguration
MustacheAutoConfiguration
Neo4jAutoConfiguration
HibernateJpaAutoConfiguration
QuartzAutoConfiguration
R2dbcAutoConfiguration
R2dbcTransactionManagerAutoConfiguration
RSocketMessagingAutoConfiguration
RSocketRequesterAutoConfiguration
RSocketServerAutoConfiguration
RSocketStrategiesAutoConfiguration
SecurityAutoConfiguration
UserDetailsServiceAutoConfiguration
SecurityFilterAutoConfiguration
ReactiveSecurityAutoConfiguration
ReactiveUserDetailsServiceAutoConfiguration
RSocketSecurityAutoConfiguration
Saml2RelyingPartyAutoConfiguration
SendGridAutoConfiguration
SessionAutoConfiguration
OAuth2ClientAutoConfiguration
ReactiveOAuth2ClientAutoConfiguration
OAuth2ResourceServerAutoConfiguration
ReactiveOAuth2ResourceServerAutoConfiguration
SolrAutoConfiguration
TaskExecutionAutoConfiguration
TaskSchedulingAutoConfiguration
ThymeleafAutoConfiguration
TransactionAutoConfiguration
JtaAutoConfiguration
ValidationAutoConfiguration
RestTemplateAutoConfiguration
EmbeddedWebServerFactoryCustomizerAutoConfiguration
HttpHandlerAutoConfiguration
ReactiveWebServerFactoryAutoConfiguration
WebFluxAutoConfiguration
ErrorWebFluxAutoConfiguration
ClientHttpConnectorAutoConfiguration
WebClientAutoConfiguration
DispatcherServletAutoConfiguration
ServletWebServerFactoryAutoConfiguration
ErrorMvcAutoConfiguration
HttpEncodingAutoConfiguration
MultipartAutoConfiguration
WebMvcAutoConfiguration
WebSocketReactiveAutoConfiguration
WebSocketServletAutoConfiguration
WebSocketMessagingAutoConfiguration
WebServicesAutoConfiguration
WebServiceTemplateAutoConfiguration

以上的类都是通过 application*.yaml 中的属性配置自动装载成 bean。这些类比较多，可以自行探索

6. 失败分析器

org.springframework.boot.diagnostics.FailureAnalyzer=\
org.springframework.boot.autoconfigure.data.redis.RedisUrlSyntaxFailureAnalyzer,\
org.springframework.boot.autoconfigure.diagnostics.analyzer.NoSuchBeanDefinitionFailureAnalyzer,\
org.springframework.boot.autoconfigure.flyway.FlywayMigrationScriptMissingFailureAnalyzer,\
org.springframework.boot.autoconfigure.jdbc.DataSourceBeanCreationFailureAnalyzer,\
org.springframework.boot.autoconfigure.jdbc.HikariDriverConfigurationFailureAnalyzer,\
org.springframework.boot.autoconfigure.r2dbc.ConnectionFactoryBeanCreationFailureAnalyzer,\
org.springframework.boot.autoconfigure.session.NonUniqueSessionRepositoryFailureAnalyzer

RedisUrlSyntaxFailureAnalyzer Redis url 语法错误
NoSuchBeanDefinitionFailureAnalyzer 没有 bean 定义
FlywayMigrationScriptMissingFailureAnalyzer Flyway 没有可用的 sql 脚本
DataSourceBeanCreationFailureAnalyzer 数据库源 bean 创建失败
HikariDriverConfigurationFailureAnalyzer HikariCP 配置失败
ConnectionFactoryBeanCreationFailureAnalyzer ConnectionFactory bean 创建失败
NonUniqueSessionRepositoryFailureAnalyzer 多个 Spring Session 错误

这些类都比较简单，可以自行探索

7. 检查模板可用提供器

org.springframework.boot.autoconfigure.template.TemplateAvailabilityProvider=\
org.springframework.boot.autoconfigure.freemarker.FreeMarkerTemplateAvailabilityProvider,\
org.springframework.boot.autoconfigure.mustache.MustacheTemplateAvailabilityProvider,\
org.springframework.boot.autoconfigure.groovy.template.GroovyTemplateAvailabilityProvider,\
org.springframework.boot.autoconfigure.thymeleaf.ThymeleafTemplateAvailabilityProvider,\
org.springframework.boot.autoconfigure.web.servlet.JspTemplateAvailabilityProvider

FreeMarkerTemplateAvailabilityProvider FreeMarker 模板检查
MustacheTemplateAvailabilityProvider Mustache 模板检查
GroovyTemplateAvailabilityProvider Groovy 模板检查
ThymeleafTemplateAvailabilityProvider Thymeleaf 模板检查
JspTemplateAvailabilityProvider Jsp 模板检查

这些类都比较简单，可以自行探索

后续

更多博客，查看 https://github.com/deepraining/blogs

作者：深雨 (@deepraining)

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

14.md

14.md

Spring 源码解析十四：SpringBoot Autoconfigure 初始化应用时加载的组件

1. 初始化器

1.1. SharedMetadataReaderFactoryContextInitializer

1.2. ConditionEvaluationReportLoggingListener

2. 应用事件监听器

3. 自动配置导入监听器

4. 自动配置导入过滤器

4.1. OnBeanCondition

4.1.1. SpringBootCondition

4.1.2. FilteringSpringBootCondition

4.1.3. SpringBootCondition

4.2. OnClassCondition

4.3. OnWebApplicationCondition

5. 自动配置

6. 失败分析器

7. 检查模板可用提供器

后续

Files

14.md

Latest commit

History

14.md

File metadata and controls

Spring 源码解析十四：SpringBoot Autoconfigure 初始化应用时加载的组件

1. 初始化器

1.1. SharedMetadataReaderFactoryContextInitializer

1.2. ConditionEvaluationReportLoggingListener

2. 应用事件监听器

3. 自动配置导入监听器

4. 自动配置导入过滤器

4.1. OnBeanCondition

4.1.1. SpringBootCondition

4.1.2. FilteringSpringBootCondition

4.1.3. SpringBootCondition

4.2. OnClassCondition

4.3. OnWebApplicationCondition

5. 自动配置

6. 失败分析器

7. 检查模板可用提供器

后续