第7-1 章：@SpringBootApplication的ComponentScan

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李延 LV6 2021-05-22

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# 使用

在@SpringBootApplication的注解上面我们发现：

@ComponentScan(excludeFilters = { @Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class),
		@Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) })
		
		
添加了TypeExcludeFilter与AutoConfigurationExcludeFilter两个用于排除自动扫描的类。我们再下面解析一下都排除了哪些内容

# TypeExcludeFilter

```java
@Override
	public boolean match(MetadataReader metadataReader, MetadataReaderFactory metadataReaderFactory)
			throws IOException {
		if (this.beanFactory instanceof ListableBeanFactory && getClass() == TypeExcludeFilter.class) {
			for (TypeExcludeFilter delegate : getDelegates()) {
				if (delegate.match(metadataReader, metadataReaderFactory)) {
					return true;
				}
			}
		}
		return false;
	}

private Collection<TypeExcludeFilter> getDelegates() {
		Collection<TypeExcludeFilter> delegates = this.delegates;
		if (delegates == null) {
			delegates = ((ListableBeanFactory) this.beanFactory).getBeansOfType(TypeExcludeFilter.class).values();
			this.delegates = delegates;
		}
		return delegates;
	}

```

我们看到首先通过beanFactory中获取TypeExcludeFilter类型的bean。并一次调用其方法，用于排除扫描的bean。

也就是我们我们可以通过向spring中注入TypeExcludeFilter类型的bean。自定义排除方案。

# AutoConfigurationExcludeFilter

```java
@Override
	public boolean match(MetadataReader metadataReader, MetadataReaderFactory metadataReaderFactory)
			throws IOException {
		return isConfiguration(metadataReader) && isAutoConfiguration(metadataReader);
	}

private boolean isConfiguration(MetadataReader metadataReader) {
		return metadataReader.getAnnotationMetadata().isAnnotated(Configuration.class.getName());
	}

private boolean isAutoConfiguration(MetadataReader metadataReader) {
		return getAutoConfigurations().contains(metadataReader.getClassMetadata().getClassName());
	}

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

```

很明显，是将有EnableAutoConfiguration的类排除掉

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