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98 lines
3.8 KiB
98 lines
3.8 KiB
5 years ago
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# Spring Import
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- Author: [HuiFer](https://github.com/huifer)
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- 源码阅读仓库: [SourceHot-spring](https://github.com/SourceHot/spring-framework-read)
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## 分析
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- org.springframework.context.annotation.Import
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```java
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@Target(ElementType.TYPE)
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@Retention(RetentionPolicy.RUNTIME)
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@Documented
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public @interface Import {
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/**
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* {@link Configuration @Configuration}, {@link ImportSelector},
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* {@link ImportBeanDefinitionRegistrar}, or regular component classes to import.
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*
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* 需要导入的类
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*/
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Class<?>[] value();
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}
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```
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### ImportBeanDefinitionRegistrar
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- 注册Import Bean
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- `org.springframework.context.annotation.ImportBeanDefinitionRegistrar`
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```java
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public interface ImportBeanDefinitionRegistrar {
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/**
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* Register bean definitions as necessary based on the given annotation metadata of
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* the importing {@code @Configuration} class.
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* <p>Note that {@link BeanDefinitionRegistryPostProcessor} types may <em>not</em> be
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* registered here, due to lifecycle constraints related to {@code @Configuration}
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* class processing.
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*
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* 对import value属性的注册
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* @param importingClassMetadata annotation metadata of the importing class
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* @param registry current bean definition registry
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*/
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void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry);
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}
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```
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- 两个实现类
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1. `org.springframework.context.annotation.AutoProxyRegistrar`
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2. `org.springframework.context.annotation.AspectJAutoProxyRegistrar`
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#### AutoProxyRegistrar
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```java
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public class AutoProxyRegistrar implements ImportBeanDefinitionRegistrar {
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private final Log logger = LogFactory.getLog(getClass());
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/**
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* 注册import bean定义
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*/
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@Override
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public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
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boolean candidateFound = false;
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// 获取注解
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Set<String> annTypes = importingClassMetadata.getAnnotationTypes();
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for (String annType : annTypes) {
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// 注解属性
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AnnotationAttributes candidate = AnnotationConfigUtils.attributesFor(importingClassMetadata, annType);
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if (candidate == null) {
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continue;
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}
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// 获取 mode 属性
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Object mode = candidate.get("mode");
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// 获取代理对象
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Object proxyTargetClass = candidate.get("proxyTargetClass");
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if (mode != null && proxyTargetClass != null && AdviceMode.class == mode.getClass() &&
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Boolean.class == proxyTargetClass.getClass()) {
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candidateFound = true;
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if (mode == AdviceMode.PROXY) {
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// 注册
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AopConfigUtils.registerAutoProxyCreatorIfNecessary(registry);
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if ((Boolean) proxyTargetClass) {
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AopConfigUtils.forceAutoProxyCreatorToUseClassProxying(registry);
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return;
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}
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}
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}
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}
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if (!candidateFound && logger.isInfoEnabled()) {
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String name = getClass().getSimpleName();
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logger.info(String.format("%s was imported but no annotations were found " +
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"having both 'mode' and 'proxyTargetClass' attributes of type " +
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"AdviceMode and boolean respectively. This means that auto proxy " +
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"creator registration and configuration may not have occurred as " +
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"intended, and components may not be proxied as expected. Check to " +
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"ensure that %s has been @Import'ed on the same class where these " +
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"annotations are declared; otherwise remove the import of %s " +
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"altogether.", name, name, name));
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}
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}
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}
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```
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