SpringBoot @ComponentScan排除扫描

指定包扫描的根路径，让 Spring 来扫描指定包及子包下的组件。不过在上面的声明中有显式的指定了两个过滤条件：

@ComponentScan(excludeFilters = {
		@Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class),
		@Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) })

AutoConfigurationExcludeFilter # match
match 方法要判断两个部分：是否是一个配置类，是否是一个自动配置类；当match方法为true，返回扫描类对象，否则过滤掉?
isAutoConfiguration

	private boolean isAutoConfiguration(MetadataReader metadataReader) {
		//查看这个方法返回值是否包含着两个部分的数据
		return getAutoConfigurations()
				.contains(metadataReader.getClassMetadata().getClassName());
	}

getAutoConfigurations

	protected List<String> getAutoConfigurations() {
		if (this.autoConfigurations == null) {
			this.autoConfigurations = SpringFactoriesLoader.loadFactoryNames(
					EnableAutoConfiguration.class, this.beanClassLoader);
		}
		return this.autoConfigurations;
	}

SpringFactoriesLoader.loadFactoryNames

public static final String FACTORIES_RESOURCE_LOCATION = "META-INF/spring.factories";

public static List<String> loadFactoryNames(Class<?> factoryClass, @Nullable ClassLoader classLoader) {
    String factoryClassName = factoryClass.getName();
    //     ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓
    return loadSpringFactories(classLoader).getOrDefault(factoryClassName, Collections.emptyList());
}

private static Map<String, List<String>> loadSpringFactories(@Nullable ClassLoader classLoader) {
    MultiValueMap<String, String> result = cache.get(classLoader);
    if (result != null) {
        return result;
    }

    try {
        // ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓
        Enumeration<URL> urls = (classLoader != null ?
                 classLoader.getResources(FACTORIES_RESOURCE_LOCATION) :
                 ClassLoader.getSystemResources(FACTORIES_RESOURCE_LOCATION));
        result = new LinkedMultiValueMap<>();
        while (urls.hasMoreElements()) {
            URL url = urls.nextElement();
            UrlResource resource = new UrlResource(url);
            Properties properties = PropertiesLoaderUtils.loadProperties(resource);
            for (Map.Entry<?, ?> entry : properties.entrySet()) {
                String factoryClassName = ((String) entry.getKey()).trim();
                for (String factoryName : StringUtils.commaDelimitedListToStringArray((String) entry.getValue())) {
                    result.add(factoryClassName, factoryName.trim());
                }
            }
        }
        cache.put(classLoader, result);
        return result;
    }
    catch (IOException ex) {
        throw new IllegalArgumentException("Unable to load factories from location [" +
                                       FACTORIES_RESOURCE_LOCATION + "]", ex);
    }
}

classLoader 去加载了指定常量路径下的资源： FACTORIES_RESOURCE_LOCATION ，而这个常量指定的路径实际是：META-INF/spring.factories
读取其中的数据后最终会封装到一个List中：

	public static List<String> loadFactoryNames(Class<?> factoryClass, @Nullable ClassLoader classLoader) {
		String factoryClassName = factoryClass.getName();
		return loadSpringFactories(classLoader).getOrDefault(factoryClassName, Collections.emptyList());
	}

这个很大的List中就有自动装配的类和启动类，于是在先前的如下代码中进行判断

return getAutoConfigurations()
				.contains(metadataReader.getClassMetadata().getClassName());

最后我们得出结论：
打了@SpringBootApplication注解后，在扫包的时候会把主启动类、自动配置类屏蔽掉！