\/*\n\u6839\u636e\u63a5\u53e3\u7c7b\u83b7\u53d6\u5176\u5b9e\u73b0\u7c7b\u7684\u5b9e\u4f8b\uff0c\u8fd9\u4e2a\u65b9\u6cd5\u8fd4\u56de\u7684\u662f\u5bf9\u8c61\u5217\u8868\u3002\nLoad and instantiate the factory implementations of the given type from \"META-INF\/spring.factories\", using the given class loader.\nThe returned factories are sorted through AnnotationAwareOrderComparator.\nIf a custom instantiation strategy is required, use loadFactoryNames(java.lang.Class<?>, java.lang.ClassLoader) to obtain all registered factory names.\n*\/\npublic static <T> List<T> loadFactories(Class<T> factoryType, @Nullable ClassLoader classLoader)\n\n\/*\n\u6839\u636e\u63a5\u53e3\u83b7\u53d6\u5176\u63a5\u53e3\u7c7b\u7684\u540d\u79f0\uff0c\u8fd9\u4e2a\u65b9\u6cd5\u8fd4\u56de\u7684\u662f\u7c7b\u540d\u7684\u5217\u8868\u3002\nLoad the fully qualified class names of factory implementations of the given type from \"META-INF\/spring.factories\", using the given class loader.\n*\/\npublic static List<String> loadFactoryNames(Class<?> factoryType, @Nullable ClassLoader classLoader)\n<\/code><\/pre>\n\u800c\u4e0a\u9762\u8fd9\u4e24\u4e2a\u65b9\u6cd5\uff0c\u6700\u7ec8\u90fd\u4f1a\u8c03\u7528\u4e00\u4e2aSpringFactoriesLoader\u7684\u79c1\u6709\u65b9\u6cd5loadSpringFactories\uff0c\u4ece\u6307\u5b9a\u7684ClassLoader\u4e2d\u83b7\u53d6spring.factories\u6587\u4ef6\uff0c\u5e76\u89e3\u6790\u5f97\u5230\u7c7b\u540d\u5217\u8868\u3002\u5177\u4f53\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n
private static Map<String, List<String>> loadSpringFactories(@Nullable ClassLoader classLoader) {\n MultiValueMap<String, String> result = cache.get(classLoader);\n if (result != null) {\n return result;\n }\n\n try {\n Enumeration<URL> urls = (classLoader != null ?\n classLoader.getResources(FACTORIES_RESOURCE_LOCATION) :\n ClassLoader.getSystemResources(FACTORIES_RESOURCE_LOCATION));\n result = new LinkedMultiValueMap<>();\n while (urls.hasMoreElements()) {\n URL url = urls.nextElement();\n UrlResource resource = new UrlResource(url);\n Properties properties = PropertiesLoaderUtils.loadProperties(resource);\n for (Map.Entry<?, ?> entry : properties.entrySet()) {\n String factoryTypeName = ((String) entry.getKey()).trim();\n for (String factoryImplementationName : StringUtils.commaDelimitedListToStringArray((String) entry.getValue())) {\n result.add(factoryTypeName, factoryImplementationName.trim());\n }\n }\n }\n cache.put(classLoader, result);\n return result;\n }\n catch (IOException ex) {\n throw new IllegalArgumentException(\"Unable to load factories from location [\" +\n FACTORIES_RESOURCE_LOCATION + \"]\", ex);\n }\n }\n<\/code><\/pre>\n\u8be5\u4ee3\u7801\u4f5c\u7528\uff1a\u904d\u5386\u6574\u4e2aClassLoader\u4e2d\u6240\u6709jar\u5305\u4e0b\u7684spring.factories\u6587\u4ef6\u3002<\/strong>spring.factories\u6587\u4ef6\u7684\u4f4d\u7f6e\uff1ajar\u5305\u4e0bMETA-INF\/spring.factories\u3002<\/p>\n\u6709\u6ca1\u6709\u611f\u89c9\u5f88\u719f\u6089\uff1fJava SPI\u7684\u8bfb\u53d6\u76ee\u5f55\u5728META-INF\/services<\/code>\u4e0b\uff0c\u5176\u5b9e\u5927\u5bb6\u5199\u4ee3\u7801\u90fd\u662f\u76f8\u4e92\u53c2\u8003\u3001\u7136\u540e\u5f62\u6210\u4e00\u4e2a\u7ea6\u5b9a\u4fd7\u6210\u4e60\u60ef\u7684\u3002<\/p>\n\u6211\u4eec\u53ef\u4ee5\u5728\u81ea\u5df1\u7684jar\u4e2d\u914d\u7f6espring.factories\u6587\u4ef6\uff0c\u4e0d\u4f1a\u5f71\u54cd\u5230\u5176\u5b83\u5730\u65b9\u7684\u914d\u7f6e\uff0c\u4e5f\u4e0d\u4f1a\u88ab\u522b\u4eba\u7684\u914d\u7f6e\u8986\u76d6\u3002<\/p>\n
\u793a\u4f8b<\/h2>\n
\u4e3e\u4e2a\u4f8b\u5b50\uff0cspring boot start\u7684\u5b9e\u73b0\u4e2d\uff0c\u5982\u4e0b\u6240\u793a\uff1a
\n![\"\"](\"http:\/\/prayerlaputa.com\/wp-content\/uploads\/2020\/09\/spring-boot-starter-factories-snapshot-300x124.jpg\")
<\/p>\n
spring-boot\u7684spring.factories\u5177\u4f53\u5185\u5bb9\u5982\u4e0b\uff1a<\/p>\n
# PropertySource Loaders\norg.springframework.boot.env.PropertySourceLoader=\\\norg.springframework.boot.env.PropertiesPropertySourceLoader,\\\norg.springframework.boot.env.YamlPropertySourceLoader\n\n# Run Listeners\norg.springframework.boot.SpringApplicationRunListener=\\\norg.springframework.boot.context.event.EventPublishingRunListener\n\n# Error Reporters\norg.springframework.boot.SpringBootExceptionReporter=\\\norg.springframework.boot.diagnostics.FailureAnalyzers\n\n# Application Context Initializers\norg.springframework.context.ApplicationContextInitializer=\\\norg.springframework.boot.context.ConfigurationWarningsApplicationContextInitializer,\\\norg.springframework.boot.context.ContextIdApplicationContextInitializer,\\\norg.springframework.boot.context.config.DelegatingApplicationContextInitializer,\\\norg.springframework.boot.rsocket.context.RSocketPortInfoApplicationContextInitializer,\\\norg.springframework.boot.web.context.ServerPortInfoApplicationContextInitializer\n\n# Application Listeners\norg.springframework.context.ApplicationListener=\\\norg.springframework.boot.ClearCachesApplicationListener,\\\norg.springframework.boot.builder.ParentContextCloserApplicationListener,\\\norg.springframework.boot.cloud.CloudFoundryVcapEnvironmentPostProcessor,\\\norg.springframework.boot.context.FileEncodingApplicationListener,\\\norg.springframework.boot.context.config.AnsiOutputApplicationListener,\\\norg.springframework.boot.context.config.ConfigFileApplicationListener,\\\norg.springframework.boot.context.config.DelegatingApplicationListener,\\\norg.springframework.boot.context.logging.ClasspathLoggingApplicationListener,\\\norg.springframework.boot.context.logging.LoggingApplicationListener,\\\norg.springframework.boot.liquibase.LiquibaseServiceLocatorApplicationListener\n\n# Environment Post Processors\norg.springframework.boot.env.EnvironmentPostProcessor=\\\norg.springframework.boot.cloud.CloudFoundryVcapEnvironmentPostProcessor,\\\norg.springframework.boot.env.SpringApplicationJsonEnvironmentPostProcessor,\\\norg.springframework.boot.env.SystemEnvironmentPropertySourceEnvironmentPostProcessor,\\\norg.springframework.boot.reactor.DebugAgentEnvironmentPostProcessor\n\n# Failure Analyzers\norg.springframework.boot.diagnostics.FailureAnalyzer=\\\norg.springframework.boot.diagnostics.analyzer.BeanCurrentlyInCreationFailureAnalyzer,\\\norg.springframework.boot.diagnostics.analyzer.BeanDefinitionOverrideFailureAnalyzer,\\\norg.springframework.boot.diagnostics.analyzer.BeanNotOfRequiredTypeFailureAnalyzer,\\\norg.springframework.boot.diagnostics.analyzer.BindFailureAnalyzer,\\\norg.springframework.boot.diagnostics.analyzer.BindValidationFailureAnalyzer,\\\norg.springframework.boot.diagnostics.analyzer.UnboundConfigurationPropertyFailureAnalyzer,\\\norg.springframework.boot.diagnostics.analyzer.ConnectorStartFailureAnalyzer,\\\norg.springframework.boot.diagnostics.analyzer.NoSuchMethodFailureAnalyzer,\\\norg.springframework.boot.diagnostics.analyzer.NoUniqueBeanDefinitionFailureAnalyzer,\\\norg.springframework.boot.diagnostics.analyzer.PortInUseFailureAnalyzer,\\\norg.springframework.boot.diagnostics.analyzer.ValidationExceptionFailureAnalyzer,\\\norg.springframework.boot.diagnostics.analyzer.InvalidConfigurationPropertyNameFailureAnalyzer,\\\norg.springframework.boot.diagnostics.analyzer.InvalidConfigurationPropertyValueFailureAnalyzer\n\n# FailureAnalysisReporters\norg.springframework.boot.diagnostics.FailureAnalysisReporter=\\\norg.springframework.boot.diagnostics.LoggingFailureAnalysisReporter\n\n<\/code><\/pre>\nspring boot\u5982\u4f55\u5229\u7528spring.factories\u8fdb\u884c\u6ce8\u5165<\/h2>\n
\u4e00\u4e2aspring boot\u9879\u76ee\uff0c\u5728\u542f\u52a8\u7c7b\u4e0a\u4f1a\u6709@SpringBootApplication<\/code>\u6ce8\u89e3\uff0c\u8be5\u6ce8\u89e3\u5b9e\u73b0\uff1a<\/p>\n@Target(ElementType.TYPE)\n@Retention(RetentionPolicy.RUNTIME)\n@Documented\n@Inherited\n@SpringBootConfiguration\n@EnableAutoConfiguration\n@ComponentScan(excludeFilters = { @Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class),\n @Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) })\npublic @interface SpringBootApplication {\n ...\n}\n<\/code><\/pre>\n\u5176\u4e2d\uff0c@EnableAutoConfiguration<\/code>\u6ce8\u89e3\u5b9a\u4e49\u5927\u4f53\u5982\u4e0b\uff1a<\/p>\n@Target(ElementType.TYPE)\n@Retention(RetentionPolicy.RUNTIME)\n@Documented\n@Inherited\n@AutoConfigurationPackage\n@Import(AutoConfigurationImportSelector.class)\npublic @interface EnableAutoConfiguration {\n ...\n}\n<\/code><\/pre>\n\u5176\u4e2d@Import(AutoConfigurationImportSelector.class)<\/code> \u5f88\u5173\u952e\uff0c@Import\u6ce8\u89e3\u901a\u8fc7\u5feb\u901f\u5bfc\u5165\u7684\u65b9\u5f0f\u5b9e\u73b0\u628a\u5b9e\u4f8b\u52a0\u5165spring\u7684IOC\u5bb9\u5668\u4e2d\uff0c\u53ef\u4ee5\u7528\u4e8e\u5bfc\u5165\u7b2c\u4e09\u65b9\u5305\u3002AutoConfigurationImportSelector\u5b9e\u73b0\u4e86ImportSelector\u63a5\u53e3\uff0c\u4efb\u4f55\u5b9e\u73b0ImportSelector\u7684\u7c7b\uff0c\u90fd\u4f1a\u5728\u542f\u52a8\u65f6\u88abspring-context\u5305ConfigurationClassParser<\/code>\u4e2d\u7684processImports<\/code>\u8fdb\u884c\u5b9e\u4f8b\u5316\uff0c\u5e76\u6267\u884cselectImports<\/code>\u65b9\u6cd5\u3002<\/p>\nAutoConfigurationImportSelector\u7684selectImports\u4ee5\u53ca\u76f8\u5173\u7684\u65b9\u6cd5\u5b9e\u73b0\u5982\u4e0b\uff1a<\/p>\n
\/*\n\u8fd9\u90e8\u5206\u662fAutoConfigurationImportSelector\u7684\u4ee3\u7801\n*\/\npublic String[] selectImports(AnnotationMetadata annotationMetadata) {\n if (!isEnabled(annotationMetadata)) {\n return NO_IMPORTS;\n }\n AutoConfigurationMetadata autoConfigurationMetadata = AutoConfigurationMetadataLoader\n .loadMetadata(this.beanClassLoader);\n AutoConfigurationEntry autoConfigurationEntry = getAutoConfigurationEntry(autoConfigurationMetadata,\n annotationMetadata);\n return StringUtils.toStringArray(autoConfigurationEntry.getConfigurations());\n}\n\nprotected AutoConfigurationEntry getAutoConfigurationEntry(AutoConfigurationMetadata autoConfigurationMetadata,\n AnnotationMetadata annotationMetadata) {\n if (!isEnabled(annotationMetadata)) {\n return EMPTY_ENTRY;\n }\n AnnotationAttributes attributes = getAttributes(annotationMetadata);\n List<String> configurations = getCandidateConfigurations(annotationMetadata, attributes);\n configurations = removeDuplicates(configurations);\n Set<String> exclusions = getExclusions(annotationMetadata, attributes);\n checkExcludedClasses(configurations, exclusions);\n configurations.removeAll(exclusions);\n configurations = filter(configurations, autoConfigurationMetadata);\n fireAutoConfigurationImportEvents(configurations, exclusions);\n return new AutoConfigurationEntry(configurations, exclusions);\n}\n\nprotected List<String> getCandidateConfigurations(AnnotationMetadata metadata, AnnotationAttributes attributes) {\n List<String> configurations = SpringFactoriesLoader.loadFactoryNames(getSpringFactoriesLoaderFactoryClass(),\n getBeanClassLoader());\n Assert.notEmpty(configurations, \"No auto configuration classes found in META-INF\/spring.factories. If you \"\n + \"are using a custom packaging, make sure that file is correct.\");\n return configurations;\n }\n\nprotected Class<?> getSpringFactoriesLoaderFactoryClass() {\n return EnableAutoConfiguration.class;\n}\n\n\n\/*\n\u4e0b\u9762\u662fAutoConfigurationMetadataLoader\u4e2d\u7684\u4ee3\u7801\n*\/\nprotected static final String PATH = \"META-INF\/spring-autoconfigure-metadata.properties\";\nstatic AutoConfigurationMetadata loadMetadata(ClassLoader classLoader) {\n return loadMetadata(classLoader, PATH);\n }\n\nstatic AutoConfigurationMetadata loadMetadata(ClassLoader classLoader, String path) {\n try {\n Enumeration<URL> urls = (classLoader != null) ? classLoader.getResources(path)\n : ClassLoader.getSystemResources(path);\n Properties properties = new Properties();\n while (urls.hasMoreElements()) {\n properties.putAll(PropertiesLoaderUtils.loadProperties(new UrlResource(urls.nextElement())));\n }\n return loadMetadata(properties);\n }\n catch (IOException ex) {\n throw new IllegalArgumentException(\"Unable to load @ConditionalOnClass location [\" + path + \"]\", ex);\n }\n}\n<\/code><\/pre>\n\u53ef\u4ee5\u770b\u5230\uff0cAutoConfigurationImportSelector\u7684selectImports\u65b9\u6cd5\u4e3b\u8981\u662f\u7528\u4e8e\u52a0\u8f7d\u7c7b\uff0c\u4f46\u4e3a\u4e86\u83b7\u53d6\u54ea\u4e9b\u7c7b\u9700\u8981\u52a0\u8f7d\uff0c\u5219\u662f\u901a\u8fc7SpringFactoriesLoader\u53bb\u52a0\u8f7d\u5bf9\u5e94\u7684spring.factories\u3002\u5927\u4f53\u8c03\u7528\u94fe\u8def\uff1a<\/p>\n
AutoConfigurationImportSelector#selectImports()\n -> AutoConfigurationImportSelector#getAutoConfigurationEntry()\n -> AutoConfigurationImportSelector#getCandidateConfigurations()\n -> SpringFactoriesLoader#loadFactoryNames()\n<\/code><\/pre>\n\u6700\u7ec8\u6267\u884c\u7684\u662f loadFactoryNames(EnableAutoConfiguration.class, \u5f53\u524dclassloader)<\/code>\uff0c \u7ed3\u5408\u4e0a\u9762Spring Factories\u7684\u6838\u5fc3<\/code>\u8fd9\u4e00\u5c0f\u8282\uff0c\u53ef\u4ee5\u83b7\u77e5\uff0cSpringFactoriesLoader\u5c06\u4f1a\u6839\u636eEnableAutoConfiguration\u63a5\u53e3\uff0c\u53bb\u6240\u6709spring.factories<\/code>\u627eEnableAutoConfiguration.class<\/code>\u6240\u5bf9\u5e94\u7684values<\/code>\uff0c\u5e76\u8fd4\u56de\u3002<\/p>\n\u5e38\u89c1\u6269\u5c55\u70b9<\/h2>\n
\u4e0a\u9762\u5df2\u7ecf\u63d0\u5230\uff0cspring factories\u9700\u8981\u7ed9\u51fa\u4e00\u4e2aspring.factories\u6587\u4ef6\uff0c\u8be5\u6587\u4ef6\u89c4\u5b9a\u4e86bean\u6ce8\u5165\u7684\u6269\u5c55\u70b9\u3002<\/p>\n
\u5e38\u89c1\u6269\u5c55\u70b9\u5982\u4e0b\uff1a<\/p>\n
# Auto Configure\uff08\u8fd9\u4e2a\u6269\u5c55\u662f\u4f7f\u7528\u7684\u6700\u591a\u7684\uff0c\u7279\u522b\u662f\u662f\u4e00\u4e9b\u516c\u5171SDK\uff0c\u4f1a\u8fd9\u501f\u52a9\u8fd9\u6269\u5c55\u5b9e\u73b0Bean\u7684\u81ea\u52a8\u6ce8\u5165\uff09\norg.springframework.boot.autoconfigure.EnableAutoConfiguration\n\n# PropertySource Loaders\norg.springframework.boot.env.PropertySourceLoader\n\n# Run Listeners\norg.springframework.boot.SpringApplicationRunListener\n\n# Error Reporters\norg.springframework.boot.SpringBootExceptionReporter\n\n# Application Context Initializers\norg.springframework.context.ApplicationContextInitializer\n\n# Application Listeners\norg.springframework.context.ApplicationListener\n\n# Environment Post Processors\norg.springframework.boot.env.EnvironmentPostProcessor\n\n# Failure Analyzers\norg.springframework.boot.diagnostics.FailureAnalyzer\n\n# FailureAnalysisReporters\norg.springframework.boot.diagnostics.FailureAnalysisReporter\n<\/code><\/pre>\n\u53c2\u8003\u8d44\u6599<\/h2>\n