springboot spring.factories说明

桃扇骨 2022-09-12 07:49 105阅读 0赞

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## springboot spring.factories说明 ##

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**spring.factories 简介**

![watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBAb1_nk5znlLDmnY7kuItfbw_size_9_color_FFFFFF_t_70_g_se_x_16][]

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**springboot-autoconfigure META-INF/spring.factories（部分）**

# Initializers
    org.springframework.context.ApplicationContextInitializer=\
    org.springframework.boot.autoconfigure.SharedMetadataReaderFactoryContextInitializer,\
    org.springframework.boot.autoconfigure.logging.ConditionEvaluationReportLoggingListener
    
    # Application Listeners
    org.springframework.context.ApplicationListener=\
    org.springframework.boot.autoconfigure.BackgroundPreinitializer
    
    # Environment Post Processors
    org.springframework.boot.env.EnvironmentPostProcessor=\
    org.springframework.boot.autoconfigure.integration.IntegrationPropertiesEnvironmentPostProcessor
    
    # Auto Configuration Import Listeners
    org.springframework.boot.autoconfigure.AutoConfigurationImportListener=\
    org.springframework.boot.autoconfigure.condition.ConditionEvaluationReportAutoConfigurationImportListener
    
    # Auto Configuration Import Filters
    org.springframework.boot.autoconfigure.AutoConfigurationImportFilter=\
    org.springframework.boot.autoconfigure.condition.OnBeanCondition,\
    org.springframework.boot.autoconfigure.condition.OnClassCondition,\
    org.springframework.boot.autoconfigure.condition.OnWebApplicationCondition
    
    # Auto Configure
    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,\
    
    。。。

**key = value：value可为多个，多个值之间用逗号间隔**

**常见应用**

自定义springboot starter
    
    将类写在org.springframework.boot.autoconfigure.EnableAutoConfiguration=\下，
    实现类的注入（包括项目中的类、项目路径外的类）

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**springboot 自动装配原理**

**                       **

**加载spring.factories自动配置类调用栈**

# SpringFactoriesLoader loadFactoryNames方法加载自动配置类
    org.springframework.core.io.support.SpringFactoriesLoader.loadFactoryNames(SpringFactoriesLoader.java:132)
    
    # AutoConfigurationImportSelector
    org.springframework.boot.autoconfigure.AutoConfigurationImportSelector.getCandidateConfigurations(AutoConfigurationImportSelector.java:178)
    org.springframework.boot.autoconfigure.AutoConfigurationImportSelector.getAutoConfigurationEntry(AutoConfigurationImportSelector.java:123)
    org.springframework.boot.autoconfigure.AutoConfigurationImportSelector$AutoConfigurationGroup.process(AutoConfigurationImportSelector.java:434)
    
    # ConfigurationClassParser
    org.springframework.context.annotation.ConfigurationClassParser$DeferredImportSelectorGrouping.getImports(ConfigurationClassParser.java:879)
    org.springframework.context.annotation.ConfigurationClassParser$DeferredImportSelectorGroupingHandler.processGroupImports(ConfigurationClassParser.java:809)
    org.springframework.context.annotation.ConfigurationClassParser$DeferredImportSelectorHandler.process(ConfigurationClassParser.java:780)
    org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:193)
    
    # ConfigurationClassPostProcessor
    org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:331)
    org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:247)
    
    # PostProcessorRegistrationDelegate
    org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.java:311)
    org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:112)
    
    # AbstractApplicationContext 
    org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:746)
    org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:564)
    
    # ServletWebServerApplicationContext refresh方法
    org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:145)
    
    # SpringApplication refresh方法
    org.springframework.boot.SpringApplication.refresh(SpringApplication.java:754)
    org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:434)
    
    # SpringApplication run方法
    org.springframework.boot.SpringApplication.run(SpringApplication.java:338)
    org.springframework.boot.SpringApplication.run(SpringApplication.java:1343)
    org.springframework.boot.SpringApplication.run(SpringApplication.java:1332)
    
    # springboot 项目启动
    com.example.demo.DemoApplication.main(DemoApplication.java:10)

**说明：springboot 版本不同，调用路径可能不一致**

**SpringFactoriesLoader**

public final class SpringFactoriesLoader {
        public static final String FACTORIES_RESOURCE_LOCATION = "META-INF/spring.factories";
        private static final Log logger = LogFactory.getLog(SpringFactoriesLoader.class);
        static final Map<ClassLoader, Map<String, List<String>>> cache = new ConcurrentReferenceHashMap();
    
        private SpringFactoriesLoader() {
        }
    
        public static <T> List<T> loadFactories(Class<T> factoryType, @Nullable ClassLoader classLoader) {
                                  //获取key=factoryType.getName()，对应所有value的实例对象
            Assert.notNull(factoryType, "'factoryType' must not be null");
            ClassLoader classLoaderToUse = classLoader;
            if (classLoader == null) {
                classLoaderToUse = SpringFactoriesLoader.class.getClassLoader();
            }
    
            List<String> factoryImplementationNames = loadFactoryNames(factoryType, classLoaderToUse);
            if (logger.isTraceEnabled()) {
                logger.trace("Loaded [" + factoryType.getName() + "] names: " + factoryImplementationNames);
            }
    
            List<T> result = new ArrayList(factoryImplementationNames.size());
            Iterator var5 = factoryImplementationNames.iterator();
    
            while(var5.hasNext()) {
                String factoryImplementationName = (String)var5.next();
                result.add(instantiateFactory(factoryImplementationName, factoryType, classLoaderToUse));
            }
    
            AnnotationAwareOrderComparator.sort(result);
            return result;
        }
    
        public static List<String> loadFactoryNames(Class<?> factoryType, @Nullable ClassLoader classLoader) {
                                   //获取key=factoryType.getName()，对应的所有value的全限定名
            ClassLoader classLoaderToUse = classLoader;
            if (classLoader == null) {
                classLoaderToUse = SpringFactoriesLoader.class.getClassLoader();
            }
    
            String factoryTypeName = factoryType.getName();
            return (List)loadSpringFactories(classLoaderToUse).getOrDefault(factoryTypeName, Collections.emptyList());
        }
    
        private static Map<String, List<String>> loadSpringFactories(ClassLoader classLoader) {
                                                 //key：spring.factories中键值对的key
                                                 //List<String>：key对应的value集合
            Map<String, List<String>> result = (Map)cache.get(classLoader);
            if (result != null) {
                return result;
            } else {
                HashMap result = new HashMap();
    
                try {
                    Enumeration urls = classLoader.getResources("META-INF/spring.factories");
    
                    while(urls.hasMoreElements()) {
                        URL url = (URL)urls.nextElement();
                        UrlResource resource = new UrlResource(url);
                        Properties properties = PropertiesLoaderUtils.loadProperties(resource);
                        Iterator var6 = properties.entrySet().iterator();
    
                        while(var6.hasNext()) {
                            Entry<?, ?> entry = (Entry)var6.next();
                            String factoryTypeName = ((String)entry.getKey()).trim();
                            String[] factoryImplementationNames = StringUtils.commaDelimitedListToStringArray((String)entry.getValue());
                            String[] var10 = factoryImplementationNames;
                            int var11 = factoryImplementationNames.length;
    
                            for(int var12 = 0; var12 < var11; ++var12) {
                                String factoryImplementationName = var10[var12];
                                ((List)result.computeIfAbsent(factoryTypeName, (key) -> {
                                    return new ArrayList();
                                })).add(factoryImplementationName.trim());
                            }
                        }
                    }
    
                    result.replaceAll((factoryType, implementations) -> {
                        return (List)implementations.stream().distinct().collect(Collectors.collectingAndThen(Collectors.toList(), Collections::unmodifiableList));
                    });
                    cache.put(classLoader, result);
                    return result;
                } catch (IOException var14) {
                    throw new IllegalArgumentException("Unable to load factories from location [META-INF/spring.factories]", var14);
                }
            }
        }
    
        private static <T> T instantiateFactory(String factoryImplementationName, Class<T> factoryType, ClassLoader classLoader) {
            try {
                Class<?> factoryImplementationClass = ClassUtils.forName(factoryImplementationName, classLoader);
                if (!factoryType.isAssignableFrom(factoryImplementationClass)) {
                    throw new IllegalArgumentException("Class [" + factoryImplementationName + "] is not assignable to factory type [" + factoryType.getName() + "]");
                } else {
                    return ReflectionUtils.accessibleConstructor(factoryImplementationClass, new Class[0]).newInstance();
                           //使用默认构造函数，实例化factoryImplementationClass
                }
            } catch (Throwable var4) {
                throw new IllegalArgumentException("Unable to instantiate factory class [" + factoryImplementationName + "] for factory type [" + factoryType.getName() + "]", var4);
            }
        }
    }

**ConfigurationClassPostProcessor**

public class ConfigurationClassPostProcessor implements BeanDefinitionRegistryPostProcessor, PriorityOrdered, ResourceLoaderAware, ApplicationStartupAware, BeanClassLoaderAware, EnvironmentAware {
    
        public void processConfigBeanDefinitions(BeanDefinitionRegistry registry) {
            List<BeanDefinitionHolder> configCandidates = new ArrayList();
            String[] candidateNames = registry.getBeanDefinitionNames();
            String[] var4 = candidateNames;
            int var5 = candidateNames.length;
    
            for(int var6 = 0; var6 < var5; ++var6) {
                String beanName = var4[var6];
                BeanDefinition beanDef = registry.getBeanDefinition(beanName);
                if (beanDef.getAttribute(ConfigurationClassUtils.CONFIGURATION_CLASS_ATTRIBUTE) != null) {
                    if (this.logger.isDebugEnabled()) {
                        this.logger.debug("Bean definition has already been processed as a configuration class: " + beanDef);
                    }
                } else if (ConfigurationClassUtils.checkConfigurationClassCandidate(beanDef, this.metadataReaderFactory)) {
                    configCandidates.add(new BeanDefinitionHolder(beanDef, beanName));
                }
            }
    
            if (!configCandidates.isEmpty()) {
                configCandidates.sort((bd1, bd2) -> {
                    int i1 = ConfigurationClassUtils.getOrder(bd1.getBeanDefinition());
                    int i2 = ConfigurationClassUtils.getOrder(bd2.getBeanDefinition());
                    return Integer.compare(i1, i2);
                });
                SingletonBeanRegistry sbr = null;
                if (registry instanceof SingletonBeanRegistry) {
                    sbr = (SingletonBeanRegistry)registry;
                    if (!this.localBeanNameGeneratorSet) {
                        BeanNameGenerator generator = (BeanNameGenerator)sbr.getSingleton("org.springframework.context.annotation.internalConfigurationBeanNameGenerator");
                        if (generator != null) {
                            this.componentScanBeanNameGenerator = generator;
                            this.importBeanNameGenerator = generator;
                        }
                    }
                }
    
                if (this.environment == null) {
                    this.environment = new StandardEnvironment();
                }
    
                ConfigurationClassParser parser = new ConfigurationClassParser(this.metadataReaderFactory, this.problemReporter, this.environment, this.resourceLoader, this.componentScanBeanNameGenerator, registry);
                Set<BeanDefinitionHolder> candidates = new LinkedHashSet(configCandidates);
                HashSet alreadyParsed = new HashSet(configCandidates.size());
    
                do {
                    StartupStep processConfig = this.applicationStartup.start("spring.context.config-classes.parse");
                    parser.parse(candidates);    //解析配置类
                    parser.validate();
                    Set<ConfigurationClass> configClasses = new LinkedHashSet(parser.getConfigurationClasses());
                    configClasses.removeAll(alreadyParsed);
                    if (this.reader == null) {
                        this.reader = new ConfigurationClassBeanDefinitionReader(registry, this.sourceExtractor, this.resourceLoader, this.environment, this.importBeanNameGenerator, parser.getImportRegistry());
                    }
    
                    this.reader.loadBeanDefinitions(configClasses);
                                               //加载配置类信息
    
                    alreadyParsed.addAll(configClasses);
                    processConfig.tag("classCount", () -> {
                        return String.valueOf(configClasses.size());
                    }).end();
                    candidates.clear();
                    if (registry.getBeanDefinitionCount() > candidateNames.length) {
                        String[] newCandidateNames = registry.getBeanDefinitionNames();
                        Set<String> oldCandidateNames = new HashSet(Arrays.asList(candidateNames));
                        Set<String> alreadyParsedClasses = new HashSet();
                        Iterator var13 = alreadyParsed.iterator();
    
                        while(var13.hasNext()) {
                            ConfigurationClass configurationClass = (ConfigurationClass)var13.next();
                            alreadyParsedClasses.add(configurationClass.getMetadata().getClassName());
                        }
    
                        String[] var24 = newCandidateNames;
                        int var25 = newCandidateNames.length;
    
                        for(int var15 = 0; var15 < var25; ++var15) {
                            String candidateName = var24[var15];
                            if (!oldCandidateNames.contains(candidateName)) {
                                BeanDefinition bd = registry.getBeanDefinition(candidateName);
                                if (ConfigurationClassUtils.checkConfigurationClassCandidate(bd, this.metadataReaderFactory) && !alreadyParsedClasses.contains(bd.getBeanClassName())) {
                                    candidates.add(new BeanDefinitionHolder(bd, candidateName));
                                }
                            }
                        }
    
                        candidateNames = newCandidateNames;
                    }
                } while(!candidates.isEmpty());
    
                if (sbr != null && !sbr.containsSingleton(IMPORT_REGISTRY_BEAN_NAME)) {
                    sbr.registerSingleton(IMPORT_REGISTRY_BEAN_NAME, parser.getImportRegistry());
                }
    
                if (this.metadataReaderFactory instanceof CachingMetadataReaderFactory) {
                    ((CachingMetadataReaderFactory)this.metadataReaderFactory).clearCache();
                }
    
            }
        }

**ConfigurationClassBeanDefinitionReader**

class ConfigurationClassBeanDefinitionReader {
    
        public void loadBeanDefinitions(Set<ConfigurationClass> configurationModel) {
                                        //加载类信息
            ConfigurationClassBeanDefinitionReader.TrackedConditionEvaluator trackedConditionEvaluator = new ConfigurationClassBeanDefinitionReader.TrackedConditionEvaluator();
            Iterator var3 = configurationModel.iterator();
    
            while(var3.hasNext()) {
                ConfigurationClass configClass = (ConfigurationClass)var3.next();
                this.loadBeanDefinitionsForConfigurationClass(configClass, trackedConditionEvaluator);
            }
    
        }
    
        private void loadBeanDefinitionsForConfigurationClass(ConfigurationClass configClass, ConfigurationClassBeanDefinitionReader.TrackedConditionEvaluator trackedConditionEvaluator) {
            if (trackedConditionEvaluator.shouldSkip(configClass)) {
                String beanName = configClass.getBeanName();
                if (StringUtils.hasLength(beanName) && this.registry.containsBeanDefinition(beanName)) {
                    this.registry.removeBeanDefinition(beanName);
                }
    
                this.importRegistry.removeImportingClass(configClass.getMetadata().getClassName());
            } else {
                if (configClass.isImported()) {
                    this.registerBeanDefinitionForImportedConfigurationClass(configClass);
                }    //注册类信息（import导入的类）
    
                Iterator var3 = configClass.getBeanMethods().iterator();
    
                while(var3.hasNext()) {
                    BeanMethod beanMethod = (BeanMethod)var3.next();
                    this.loadBeanDefinitionsForBeanMethod(beanMethod);
                }    //注册类信息（@Bean）
    
                this.loadBeanDefinitionsFromImportedResources(configClass.getImportedResources());
                    //加载注册ImportedResources导入的类
                this.loadBeanDefinitionsFromRegistrars(configClass.getImportBeanDefinitionRegistrars());
                    //加载注册ImportBeanDefinitionRegistrar导入的类
            }
        }

## \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* ##

**示例**

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**pojo 层**

**Person**

@Data
    public class Person {
    
        private String name="gtlx";
        private Integer age=20;
    }

**\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\***

**service 层**

**HelloService**

public interface HelloService {
    
        void fun();
    }

**                     **

**\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\***

**service.impl 层**

**HelloServiceImpl**

public class HelloServiceImpl implements HelloService {
    
        @Override
        public void fun() {
            System.out.println("hello");
        }
    }

**HelloServiceImpl2**

public class HelloServiceImpl2 implements HelloService {
    
        @Override
        public void fun() {
            System.out.println("hello 2");
        }
    }

**\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\***

**controller 层**

**HelloController**

@RestController
    public class HelloController {
    
        @Resource
        private Person person;
    
        @Resource
        private ApplicationContext applicationContext;
    
        @Resource
        private List<HelloService> helloServiceList;
    
        @RequestMapping("/hello")
        public String hello(){
            System.out.println(person);
            helloServiceList.forEach(HelloService::fun);
    
            System.out.println();
            System.out.println(applicationContext.getBean("com.example.demo.pojo.Person"));
            ((HelloService)applicationContext.getBean("com.example.demo.service.impl.HelloServiceImpl")).fun();
            ((HelloService)applicationContext.getBean("com.example.demo.service.impl.HelloServiceImpl2")).fun();
    
            System.out.println();
            SpringFactoriesLoader.loadFactoryNames(HelloService.class,null).forEach(System.out::println);
            SpringFactoriesLoader.loadFactories(HelloService.class,null).forEach(System.out::println);
            System.out.println("EnableAutoConfiguration size："+SpringFactoriesLoader.loadFactoryNames(EnableAutoConfiguration.class,null).size());
    
            return "success";
        }
    }

**\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\***

**resources**

**新建目录META-INF**

![watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBAb1_nk5znlLDmnY7kuItfbw_size_9_color_FFFFFF_t_70_g_se_x_16 2][]

**spring.factories**

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
      com.example.demo.pojo.Person,\
      com.example.demo.service.impl.HelloServiceImpl,\
      com.example.demo.service.impl.HelloServiceImpl2
    
    com.example.demo.service.HelloService=\
      com.example.demo.service.impl.HelloServiceImpl,\
      com.example.demo.service.impl.HelloServiceImpl2

## \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* ##

**使用测试**

**localhost:8080/hello，控制台输出：**

2021-09-25 10:22:42.646  INFO 3280 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Initializing Servlet 'dispatcherServlet'
    2021-09-25 10:22:42.647  INFO 3280 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Completed initialization in 1 ms
    Person(name=gtlx, age=20)
    hello
    hello 2
    
    Person(name=gtlx, age=20)
    hello
    hello 2
    
    com.example.demo.service.impl.HelloServiceImpl
    com.example.demo.service.impl.HelloServiceImpl2
    com.example.demo.service.impl.HelloServiceImpl@6e2d868f
    com.example.demo.service.impl.HelloServiceImpl2@6c79885e
    EnableAutoConfiguration size：134

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