死磕源码系列【springcloud之BootstrapImportSelector将BootstrapConfiguration配置加载到容器源码分析】

你的名字 2022-12-27 07:26 64阅读 0赞

在BootstrapApplicationListener监听器中会将BootstrapImportSelectorConfiguration配置类注入到IOC容器，配置类上有一个@Import注解将BootstrapImportSelector类注入容器并获取spring.factories配置中key为org.springframework.cloud.bootstrap.BootstrapConfiguration的配置组件；

@Configuration(proxyBeanMethods = false)
    @Import(BootstrapImportSelector.class)
    public class BootstrapImportSelectorConfiguration { 
    
    }

##### BootstrapImportSelector类是DeferredImportSelector个延迟selector，会在所有的类加载完成后加载spring.factories配置文件中的配置： #####

public class BootstrapImportSelector implements EnvironmentAware, DeferredImportSelector { 
    
    	private Environment environment;
    
    	private MetadataReaderFactory metadataReaderFactory = new CachingMetadataReaderFactory();
    
    	@Override
    	public void setEnvironment(Environment environment) { 
    		this.environment = environment;
    	}
    
    	@Override
    	public String[] selectImports(AnnotationMetadata annotationMetadata) { 
        //获取当前的类加载器
    		ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
    		// 通过SpringFactoriesLoader获取配置spring.factories中key为org.springframework.cloud.bootstrap.BootstrapConfiguration的组件
    		List<String> names = new ArrayList<>(SpringFactoriesLoader
    				.loadFactoryNames(BootstrapConfiguration.class, classLoader));
        //获取属性配置文件中key为spring.cloud.bootstrap.sources的组件，并将其加入到集合
    		names.addAll(Arrays.asList(StringUtils.commaDelimitedListToStringArray(
    				this.environment.getProperty("spring.cloud.bootstrap.sources", ""))));
    
    		List<OrderedAnnotatedElement> elements = new ArrayList<>();
    		for (String name : names) { 
    			try { 
            // 将组将包装成OrderedAnnotatedElement对象加入集合，包含类名、order对象、order值
    				elements.add(
    						new OrderedAnnotatedElement(this.metadataReaderFactory, name));
    			}
    			catch (IOException e) { 
    				continue;
    			}
    		}
        //按照优先级排序
    		AnnotationAwareOrderComparator.sort(elements);
    		//获取所有的组件类名
    		String[] classNames = elements.stream().map(e -> e.name).toArray(String[]::new);
    
    		return classNames;
    	}
    	}

总结：此类会将springcloud中bootstrap上下文需要加载的组件注入到IOC容器，其spring.factories配置文件中的配置key为org.springframework.cloud.bootstrap.BootstrapConfiguration。

GitHub地址：[https://github.com/mingyang66/spring-parent][https_github.com_mingyang66_spring-parent]

[https_github.com_mingyang66_spring-parent]: https://github.com/mingyang66/spring-parent