Spring源码(三)-Context的创建核心逻辑(下)

2020-05-28 00:00:00 方法 赋值 注册 相关信息 完成了


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. 

  2.               RootBeanDefinition def = new RootBeanDefinition(ConfigurationClassPostProcessor.class);  
    3. 

  3.               def.setSource(source);  
    4. 

  4.               beanDefs.add(registerPostProcessor(registry, def, CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME));  
    5. 

  5.           }
    6.

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. 

  2.         BeanDefinitionRegistry registry, RootBeanDefinition definition, String beanName) {
    3. 


    4. 

  4.     definition.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
    5. 

  5.     registry.registerBeanDefinition(beanName, definition);
    6. 

  6.     return new BeanDefinitionHolder(definition, beanName);
    7. 

  7. }
    8.

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

    

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

  2.         throws BeanDefinitionStoreException {
    3. 


    4. 

  4.     this.beanFactory.registerBeanDefinition(beanName, beanDefinition);
    5. 

  5. }
    6.

其中this.beanFactory为DefaultListableBeanFactory实例

    

  1. @Override
    2. 

  2. public void registerBeanDefinition(String beanName, BeanDefinition beanDefinition)
    3. 

  3.         throws BeanDefinitionStoreException {
    4. 


    5. 

  5.     Assert.hasText(beanName, "Bean name must not be empty");
    6. 

  6.     Assert.notNull(beanDefinition, "BeanDefinition must not be null");
    7. 


    8. 

  8.     if (beanDefinition instanceof AbstractBeanDefinition) {
    9. 

  9.         try {
    10. 

  10.             ((AbstractBeanDefinition) beanDefinition).validate();
    11. 

  11.         }
    12. 

  12.         catch (BeanDefinitionValidationException ex) {
    13. 

  13.             throw new BeanDefinitionStoreException(beanDefinition.getResourceDescription(), beanName,
    14. 

  14.                     "Validation of bean definition failed", ex);
    15. 

  15.         }
    16. 

  16.     }
    17. 


    18. 

  18.     BeanDefinition oldBeanDefinition;
    19. 


    20. 

  20.     oldBeanDefinition = this.beanDefinitionMap.get(beanName);
    21. 

  21.     if (oldBeanDefinition != null) {
    22. 

  22.         if (!isAllowBeanDefinitionOverriding()) {
    23. 

  23.             throw new BeanDefinitionStoreException(beanDefinition.getResourceDescription(), beanName,
    24. 

  24.                     "Cannot register bean definition [" + beanDefinition + "] for bean '" + beanName +
    25. 

  25.                     "': There is already [" + oldBeanDefinition + "] bound.");
    26. 

  26.         }
    27. 

  27.         else if (oldBeanDefinition.getRole() < beanDefinition.getRole()) {
    28. 

  28.             // e.g. was ROLE_APPLICATION, now overriding with ROLE_SUPPORT or ROLE_INFRASTRUCTURE
    29. 

  29.             if (this.logger.isWarnEnabled()) {
    30. 

  30.                 this.logger.warn("Overriding user-defined bean definition for bean '" + beanName +
    31. 

  31.                         "' with a framework-generated bean definition: replacing [" +
    32. 

  32.                         oldBeanDefinition + "] with [" + beanDefinition + "]");
    33. 

  33.             }
    34. 

  34.         }
    35. 

  35.         else if (!beanDefinition.equals(oldBeanDefinition)) {
    36. 

  36.             if (this.logger.isInfoEnabled()) {
    37. 

  37.                 this.logger.info("Overriding bean definition for bean '" + beanName +
    38. 

  38.                         "' with a different definition: replacing [" + oldBeanDefinition +
    39. 

  39.                         "] with [" + beanDefinition + "]");
    40. 

  40.             }
    41. 

  41.         }
    42. 

  42.         else {
    43. 

  43.             if (this.logger.isDebugEnabled()) {
    44. 

  44.                 this.logger.debug("Overriding bean definition for bean '" + beanName +
    45. 

  45.                         "' with an equivalent definition: replacing [" + oldBeanDefinition +
    46. 

  46.                         "] with [" + beanDefinition + "]");
    47. 

  47.             }
    48. 

  48.         }
    49. 

  49.         this.beanDefinitionMap.put(beanName, beanDefinition);
    50. 

  50.     }
    51. 

  51.     else {
    52. 

  52.         if (hasBeanCreationStarted()) {
    53. 

  53.             // Cannot modify startup-time collection elements anymore (for stable iteration)
    54. 

  54.             synchronized (this.beanDefinitionMap) {
    55. 

  55.                 this.beanDefinitionMap.put(beanName, beanDefinition);
    56. 

  56.                 List<String> updatedDefinitions = new ArrayList<>(this.beanDefinitionNames.size() + 1);
    57. 

  57.                 updatedDefinitions.addAll(this.beanDefinitionNames);
    58. 

  58.                 updatedDefinitions.add(beanName);
    59. 

  59.                 this.beanDefinitionNames = updatedDefinitions;
    60. 

  60.                 if (this.manualSingletonNames.contains(beanName)) {
    61. 

  61.                     Set<String> updatedSingletons = new LinkedHashSet<>(this.manualSingletonNames);
    62. 

  62.                     updatedSingletons.remove(beanName);
    63. 

  63.                     this.manualSingletonNames = updatedSingletons;
    64. 

  64.                 }
    65. 

  65.             }
    66. 

  66.         }
    67. 

  67.         else {
    68. 

  68.             // Still in startup registration phase
    69. 

  69.             this.beanDefinitionMap.put(beanName, beanDefinition);
    70. 

  70.             this.beanDefinitionNames.add(beanName);
    71. 

  71.             this.manualSingletonNames.remove(beanName);
    72. 

  72.         }
    73. 

  73.         this.frozenBeanDefinitionNames = null;
    74. 

  74.     }
    75. 


    76. 

  76.     if (oldBeanDefinition != null || containsSingleton(beanName)) {
    77. 

  77.         resetBeanDefinition(beanName);
    78. 

  78.     }
    79. 

  79. }
    80.

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，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. 

  2.     // Cannot modify startup-time collection elements anymore (for stable iteration)
    3. 

  3.     synchronized (this.beanDefinitionMap) {
    4. 

  4.         this.beanDefinitionMap.put(beanName, beanDefinition);
    5. 

  5.         List<String> updatedDefinitions = new ArrayList<>(this.beanDefinitionNames.size() + 1);
    6. 

  6.         updatedDefinitions.addAll(this.beanDefinitionNames);
    7. 

  7.         updatedDefinitions.add(beanName);
    8. 

  8.         this.beanDefinitionNames = updatedDefinitions;
    9. 

  9.         if (this.manualSingletonNames.contains(beanName)) {
    10. 

  10.             Set<String> updatedSingletons = new LinkedHashSet<>(this.manualSingletonNames);
    11. 

  11.             updatedSingletons.remove(beanName);
    12. 

  12.             this.manualSingletonNames = updatedSingletons;
    13. 

  13.         }
    14. 

  14.     }
    15. 

  15. }
    16. 

  16. else {
    17. 

  17.     // Still in startup registration phase
    18. 

  18.     this.beanDefinitionMap.put(beanName, beanDefinition);
    19. 

  19.     this.beanDefinitionNames.add(beanName);
    20. 

  20.     this.manualSingletonNames.remove(beanName);
    21. 

  21. }
    22. 

  22. this.frozenBeanDefinitionNames = null;
    23.

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. 

  2.         this(registry, useDefaultFilters, getOrCreateEnvironment(registry));  
    3. 

  3.     }
    4.

调用内部方法

    

  1. public ClassPathBeanDefinitionScanner(BeanDefinitionRegistry registry, boolean useDefaultFilters,
    2. 

  2.         Environment environment, @Nullable ResourceLoader resourceLoader) {
    3. 


    4. 

  4.     Assert.notNull(registry, "BeanDefinitionRegistry must not be null");
    5. 

  5.     this.registry = registry;
    6. 


    7. 

  7.     if (useDefaultFilters) {
    8. 

  8.         //注册默认拦截器，将Component、ManagedBean、Named注解增加到包含过滤规则中。
    9. 

  9.         registerDefaultFilters();
    10. 

  10.     }
    11. 

  11.     setEnvironment(environment);
    12. 

  12.     //完成对resourcePatternResolver以及metadataReaderFactory的赋值操作。
    13. 

  13.     setResourceLoader(resourceLoader);
    14. 

  14. }
    15.

调用super构造

    

  1. public ClassPathScanningCandidateComponentProvider(boolean useDefaultFilters, Environment environment) {  
    2. 

  2.         if (useDefaultFilters) {  
    3. 

  3.             registerDefaultFilters();  
    4. 

  4.         }  
    5. 

  5.         Assert.notNull(environment, "Environment must not be null");  
    6. 

  6.         this.environment = environment;  
    7. 

  7. }
    8.

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. 

  2.         this.includeFilters.add(new AnnotationTypeFilter(Component.class));  
    3. 

  3.         ClassLoader cl = ClassPathScanningCandidateComponentProvider.class.getClassLoader();  
    4. 

  4.         try {  
    5. 

  5.             this.includeFilters.add(new AnnotationTypeFilter(  
    6. 

  6.                     ((Class<? extends Annotation>) ClassUtils.forName("javax.annotation.ManagedBean", cl)), false));  
    7. 

  7.             logger.debug("JSR-250 'javax.annotation.ManagedBean' found and supported for component scanning");  
    8. 

  8.         }  
    9. 

  9.         catch (ClassNotFoundException ex) {  
    10. 

  10.             // JSR-250 1.1 API (as included in Java EE 6) not available - simply skip.
    11. 

  11.         }  
    12. 

  12.         try {  
    13. 

  13.             this.includeFilters.add(new AnnotationTypeFilter(  
    14. 

  14.                     ((Class<? extends Annotation>) ClassUtils.forName("javax.inject.Named", cl)), false));  
    15. 

  15.             logger.debug("JSR-330 'javax.inject.Named' annotation found and supported for component scanning");  
    16. 

  16.         }  
    17. 

  17.         catch (ClassNotFoundException ex) {  
    18. 

  18.             // JSR-330 API not available - simply skip.
    19. 

  19.         }  
    20. 

  20.     }
    21.

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

    

  1. setResourceLoader((ResourceLoader) this.registry)
    2. 

  2. public void setResourceLoader(@Nullable ResourceLoader resourceLoader) {
    3. 

  3.     this.resourcePatternResolver = ResourcePatternUtils.getResourcePatternResolver(resourceLoader);
    4. 

  4.     this.metadataReaderFactory = new CachingMetadataReaderFactory(resourceLoader);
    5. 

  5.     this.componentsIndex = CandidateComponentsIndexLoader.loadIndex(this.resourcePatternResolver.getClassLoader());
    6. 

  6. }
    7.

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

 



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