Spring源码(三)-Context的创建核心逻辑(下)

由于该篇文章较多，所以就拆分为了上下两篇，接上面完成了beanFactory的信息处理，接下来是bean的相关定义的处理。

1、BEANDEFINITION

获取完beanFactory的之后，代码涉及到了一些bean的定义，接下来看beanDefination的定义。

1、BeanDefinition 设计bean相关信息

2、BeanDefinitionHolder 封装bean定义相关信息，以及bean名称、别名等

3、BeanDefinitionRegistry 持有所有注册的bean相关信息

下面我们接着上面一篇 registerAnnotationConfigProcessors()方法的分析。

1. if (!registry.containsBeanDefinition(CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME)) {

2. RootBeanDefinition def = new RootBeanDefinition(ConfigurationClassPostProcessor.class);

3. def.setSource(source);

4. beanDefs.add(registerPostProcessor(registry, def, CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME));

5. }

这段代码以及其紧跟的代码为创建若干bean，其中

1. registerPostProcessor(registry, def, CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME)

表示注册名称为 org.springframework.context.annotation.internalConfigurationAnnotationProcessor，beanClass对应为ConfigurationClassPostProcessor的bean

2、BEAN注册

1. private static BeanDefinitionHolder registerPostProcessor(

2. BeanDefinitionRegistry registry, RootBeanDefinition definition, String beanName) {

3. definition.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);

4. registry.registerBeanDefinition(beanName, definition);

5. return new BeanDefinitionHolder(definition, beanName);

6. }

其中 registry.registerBeanDefinition(beanName,definition)调用GenericApplicationContext中的方法

1. public void registerBeanDefinition(String beanName, BeanDefinition beanDefinition)

2. throws BeanDefinitionStoreException {

3. this.beanFactory.registerBeanDefinition(beanName, beanDefinition);

4. }

其中this.beanFactory为DefaultListableBeanFactory实例

1. @Override

2. public void registerBeanDefinition(String beanName, BeanDefinition beanDefinition)

3. throws BeanDefinitionStoreException {

4. Assert.hasText(beanName, "Bean name must not be empty");

5. Assert.notNull(beanDefinition, "BeanDefinition must not be null");

6. if (beanDefinition instanceof AbstractBeanDefinition) {

7. try {

8. ((AbstractBeanDefinition) beanDefinition).validate();

9. }

10. catch (BeanDefinitionValidationException ex) {

11. throw new BeanDefinitionStoreException(beanDefinition.getResourceDescription(), beanName,

12. "Validation of bean definition failed", ex);

13. }

14. }

15. BeanDefinition oldBeanDefinition;

16. oldBeanDefinition = this.beanDefinitionMap.get(beanName);

17. if (oldBeanDefinition != null) {

18. if (!isAllowBeanDefinitionOverriding()) {

19. throw new BeanDefinitionStoreException(beanDefinition.getResourceDescription(), beanName,

20. "Cannot register bean definition [" + beanDefinition + "] for bean '" + beanName +

21. "': There is already [" + oldBeanDefinition + "] bound.");

22. }

23. else if (oldBeanDefinition.getRole() < beanDefinition.getRole()) {

24. // e.g. was ROLE_APPLICATION, now overriding with ROLE_SUPPORT or ROLE_INFRASTRUCTURE

25. if (this.logger.isWarnEnabled()) {

26. this.logger.warn("Overriding user-defined bean definition for bean '" + beanName +

27. "' with a framework-generated bean definition: replacing [" +

28. oldBeanDefinition + "] with [" + beanDefinition + "]");

29. }

30. }

31. else if (!beanDefinition.equals(oldBeanDefinition)) {

32. if (this.logger.isInfoEnabled()) {

33. this.logger.info("Overriding bean definition for bean '" + beanName +

34. "' with a different definition: replacing [" + oldBeanDefinition +

35. "] with [" + beanDefinition + "]");

36. }

37. }

38. else {

39. if (this.logger.isDebugEnabled()) {

40. this.logger.debug("Overriding bean definition for bean '" + beanName +

41. "' with an equivalent definition: replacing [" + oldBeanDefinition +

42. "] with [" + beanDefinition + "]");

43. }

44. }

45. this.beanDefinitionMap.put(beanName, beanDefinition);

46. }

47. else {

48. if (hasBeanCreationStarted()) {

49. // Cannot modify startup-time collection elements anymore (for stable iteration)

50. synchronized (this.beanDefinitionMap) {

51. this.beanDefinitionMap.put(beanName, beanDefinition);

52. List<String> updatedDefinitions = new ArrayList<>(this.beanDefinitionNames.size() + 1);

53. updatedDefinitions.addAll(this.beanDefinitionNames);

54. updatedDefinitions.add(beanName);

55. this.beanDefinitionNames = updatedDefinitions;

56. if (this.manualSingletonNames.contains(beanName)) {

57. Set<String> updatedSingletons = new LinkedHashSet<>(this.manualSingletonNames);

58. updatedSingletons.remove(beanName);

59. this.manualSingletonNames = updatedSingletons;

60. }

61. }

62. }

63. else {

64. // Still in startup registration phase

65. this.beanDefinitionMap.put(beanName, beanDefinition);

66. this.beanDefinitionNames.add(beanName);

67. this.manualSingletonNames.remove(beanName);

68. }

69. this.frozenBeanDefinitionNames = null;

70. }

71. if (oldBeanDefinition != null || containsSingleton(beanName)) {

72. resetBeanDefinition(beanName);

73. }

74. }

以上方法完成了bean的注册；1、首先完成校验

1. ((AbstractBeanDefinition) beanDefinition).validate()

2、接下来从map中获取bean，首次获取肯定是空

1. oldBeanDefinition = this.beanDefinitionMap.get(beanName);

3、为空进入以下代码

1. if (hasBeanCreationStarted()) {

2. // Cannot modify startup-time collection elements anymore (for stable iteration)

3. synchronized (this.beanDefinitionMap) {

4. this.beanDefinitionMap.put(beanName, beanDefinition);

5. List<String> updatedDefinitions = new ArrayList<>(this.beanDefinitionNames.size() + 1);

6. updatedDefinitions.addAll(this.beanDefinitionNames);

7. updatedDefinitions.add(beanName);

8. this.beanDefinitionNames = updatedDefinitions;

9. if (this.manualSingletonNames.contains(beanName)) {

10. Set<String> updatedSingletons = new LinkedHashSet<>(this.manualSingletonNames);

11. updatedSingletons.remove(beanName);

12. this.manualSingletonNames = updatedSingletons;

13. }

14. }

15. }

16. else {

17. // Still in startup registration phase

18. this.beanDefinitionMap.put(beanName, beanDefinition);

19. this.beanDefinitionNames.add(beanName);

20. this.manualSingletonNames.remove(beanName);

21. }

22. this.frozenBeanDefinitionNames = null;

这里顺便解释下，在从map中获取到bean时表示bean已经注册，则会判断是否可以覆盖oldBean，也需要判断bean对应的Role级别

以上完成了AnnotationConfigEmbeddedWebApplicationContext中 AnnotatedBeanDefinitionReader实例的构造

接下来为ClassPathBeanDefinitionScanner实例的创建

1. public ClassPathBeanDefinitionScanner(BeanDefinitionRegistry registry, boolean useDefaultFilters) {

2. this(registry, useDefaultFilters, getOrCreateEnvironment(registry));

3. }

调用内部方法

1. public ClassPathBeanDefinitionScanner(BeanDefinitionRegistry registry, boolean useDefaultFilters,

2. Environment environment, @Nullable ResourceLoader resourceLoader) {

3. Assert.notNull(registry, "BeanDefinitionRegistry must not be null");

4. this.registry = registry;

5. if (useDefaultFilters) {

6. //注册默认拦截器，将Component、ManagedBean、Named注解增加到包含过滤规则中。

7. registerDefaultFilters();

8. }

9. setEnvironment(environment);

10. //完成对resourcePatternResolver以及metadataReaderFactory的赋值操作。

11. setResourceLoader(resourceLoader);

12. }

调用super构造

1. public ClassPathScanningCandidateComponentProvider(boolean useDefaultFilters, Environment environment) {

2. if (useDefaultFilters) {

3. registerDefaultFilters();

4. }

5. Assert.notNull(environment, "Environment must not be null");

6. this.environment = environment;

7. }

在该方法中完成了environment的赋值以及为ClassPathScanningCandidateComponentProvider完成了默认过滤器的注册

1. protected void registerDefaultFilters() {

2. this.includeFilters.add(new AnnotationTypeFilter(Component.class));

3. ClassLoader cl = ClassPathScanningCandidateComponentProvider.class.getClassLoader();

4. try {

5. this.includeFilters.add(new AnnotationTypeFilter(

6. ((Class<? extends Annotation>) ClassUtils.forName("javax.annotation.ManagedBean", cl)), false));

7. logger.debug("JSR-250 'javax.annotation.ManagedBean' found and supported for component scanning");

8. }

9. catch (ClassNotFoundException ex) {

10. // JSR-250 1.1 API (as included in Java EE 6) not available - simply skip.

11. }

12. try {

13. this.includeFilters.add(new AnnotationTypeFilter(

14. ((Class<? extends Annotation>) ClassUtils.forName("javax.inject.Named", cl)), false));

15. logger.debug("JSR-330 'javax.inject.Named' annotation found and supported for component scanning");

16. }

17. catch (ClassNotFoundException ex) {

18. // JSR-330 API not available - simply skip.

19. }

20. }

将Component、ManagedBean、Named注解增加到包含过滤规则中。

1. setResourceLoader((ResourceLoader) this.registry)

2. public void setResourceLoader(@Nullable ResourceLoader resourceLoader) {

3. this.resourcePatternResolver = ResourcePatternUtils.getResourcePatternResolver(resourceLoader);

4. this.metadataReaderFactory = new CachingMetadataReaderFactory(resourceLoader);

5. this.componentsIndex = CandidateComponentsIndexLoader.loadIndex(this.resourcePatternResolver.getClassLoader());

6. }

完成对resourcePatternResolver以及metadataReaderFactory的赋值操作。至此，完成了对上下文的创建

代码的构建请参考 github该地址有相应代码的注释

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