写了BeanFactoryPostProcessor的博客才发现，需要提前先介绍spring在解析之前做的容器准备，要不然感觉直接介绍解析源码的话，会有一点懵逼，这里会介绍Spring容器前期准备。
这里问题问题：AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(MainConfig.class);这句代码相信很多人都用过并且很熟悉，但是大家有思考过，它为了我们做了哪些事情？
一AnnotationConfigApplicationContext的构造函数 i1:org.springframework.context.annotation.AnnotationConfigApplicationContext#AnnotationConfigApplicationContext public AnnotationConfigApplicationContext(Class... annotatedClasses) {
// 调用无参的构造器，会调用父类的无参构造器
this();
// 注册配合类
register(annotatedClasses);
// 容器刷新
refresh();
}
i2>org.springframework.context.support.GenericApplicationContext#GenericApplicationContext()
然后我们看下父类的构造函数，调用父类的构造函数，创建一个IOC容器。
public GenericApplicationContext() {
this.beanFactory = new DefaultListableBeanFactory();
}
i3>org.springframework.context.annotation.AnnotationConfigApplicationContext#AnnotationConfigApplicationContext()
然后调用自己的构造方法：
public AnnotationConfigApplicationContext() {
// 为IOC容器赋值，AnnotatedBeanDefinitionReader(注解bean定义的读取器)
this.reader = new AnnotatedBeanDefinitionReader(this);
// 为IOC容器赋值 类路径下的bean定义扫描器
this.scanner = new ClassPathBeanDefinitionScanner(this);
}
i3.1>org.springframework.context.annotation.AnnotatedBeanDefinitionReader#AnnotatedBeanDefinitionReader
org.springframework.context.annotation.AnnotatedBeanDefinitionReader#AnnotatedBeanDefinitionReader 为bean定义读取器赋值
public AnnotatedBeanDefinitionReader(BeanDefinitionRegistry registry) {
this(registry, getOrCreateEnvironment(registry));
}
i3.1.1>org.springframework.context.annotation.AnnotatedBeanDefinitionReader#getOrCreateEnvironment
org.springframework.context.annotation.AnnotatedBeanDefinitionReader#getOrCreateEnvironment 创建环境
private static Environment getOrCreateEnvironment(BeanDefinitionRegistry registry) {
Assert.notNull(registry, "BeanDefinitionRegistry must not be null");
if (registry instanceof EnvironmentCapable) {
return ((EnvironmentCapable) registry).getEnvironment();
}
return new StandardEnvironment();
}
i3.2>org.springframework.context.annotation.Conditionevaluator 创建一个条件计算器对象
public AnnotatedBeanDefinitionReader(BeanDefinitionRegistry registry, Environment environment) {
Assert.notNull(registry, "BeanDefinitionRegistry must not be null");
Assert.notNull(environment, "Environment must not be null");
this.registry = registry;
this.conditionevaluator = new Conditionevaluator(registry, environment, null);
AnnotationConfigUtils.registerAnnotationConfigProcessors(this.registry);
}
条件计算器对象。
public ConditionContextImpl(BeanDefinitionRegistry registry, Environment environment, ResourceLoader resourceLoader) {
this.registry = registry;
this.beanFactory = deduceBeanFactory(registry);
this.environment = (environment != null ? environment : deduceEnvironment(registry));
this.resourceLoader = (resourceLoader != null ? resourceLoader : deduceResourceLoader(registry));
}
i3.3> AnnotationConfigUtils.registerAnnotationConfigProcessors(this.registry);为容器注册系统的bean定义信息
- 首先获取一个IOC容器
- 注册一个配置类解析器的bean定义ConfigurationClassPostProcessor
- 设置@AutoWired注解解析器的bean定义
- 设置@Required注解处理器
- 检查是否支持JSR250规范，如果支持则注册解析JSR250规范的注解
- 检查是否支持jpa，若支持则注册jpa规范的注解
- 注册解析@EventListener的注解
public static SetregisterAnnotationConfigProcessors( BeanDefinitionRegistry registry, Object source) { // 获取一个IOC容器 DefaultListableBeanFactory beanFactory = unwrapDefaultListableBeanFactory(registry); if (beanFactory != null) { if (!(beanFactory.getDependencyComparator() instanceof AnnotationAwareOrderComparator)) { beanFactory.setDependencyComparator(AnnotationAwareOrderComparator.INSTANCE); } if (!(beanFactory.getAutowireCandidateResolver() instanceof ContextAnnotationAutowireCandidateResolver)) { beanFactory.setAutowireCandidateResolver(new ContextAnnotationAutowireCandidateResolver()); } } Set beanDefs = new linkedHashSet (8); // 注册一个配置类解析器的bean定义ConfigurationClassPostProcessor if (!registry.containsBeanDefinition(CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME)) { RootBeanDefinition def = new RootBeanDefinition(ConfigurationClassPostProcessor.class); def.setSource(source); beanDefs.add(registerPostProcessor(registry, def, CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME)); } // 设置AutoWired注解解析器的bean定义信息 if (!registry.containsBeanDefinition(AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME)) { RootBeanDefinition def = new RootBeanDefinition(AutowiredAnnotationBeanPostProcessor.class); def.setSource(source); beanDefs.add(registerPostProcessor(registry, def, AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME)); }
// 注册解析@Required注解的处理器
if (!registry.containsBeanDefinition(REQUIRED_ANNOTATION_PROCESSOR_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition(RequiredAnnotationBeanPostProcessor.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, REQUIRED_ANNOTATION_PROCESSOR_BEAN_NAME));
}
// 检查是否支持JSR250规范，如果支持则注册JSR250规范的注解
if (jsr250Present && !registry.containsBeanDefinition(COMMON_ANNOTATION_PROCESSOR_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition(CommonAnnotationBeanPostProcessor.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, COMMON_ANNOTATION_PROCESSOR_BEAN_NAME));
}
// 检查是否支持jpa，若支持注册解析jpa注解的规范
if (jpaPresent && !registry.containsBeanDefinition(PERSISTENCE_ANNOTATION_PROCESSOR_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition();
try {
def.setBeanClass(ClassUtils.forName(PERSISTENCE_ANNOTATION_PROCESSOR_CLASS_NAME,
AnnotationConfigUtils.class.getClassLoader()));
}
catch (ClassNotFoundException ex) {
throw new IllegalStateException(
"Cannot load optional framework class: " + PERSISTENCE_ANNOTATION_PROCESSOR_CLASS_NAME, ex);
}
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, PERSISTENCE_ANNOTATION_PROCESSOR_BEAN_NAME));
}
// 注册解析@EventListener的注解
if (!registry.containsBeanDefinition(EVENT_LISTENER_PROCESSOR_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition(EventListenerMethodProcessor.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, EVENT_LISTENER_PROCESSOR_BEAN_NAME));
}
if (!registry.containsBeanDefinition(EVENT_LISTENER_FACTORY_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition(DefaultEventListenerFactory.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, EVENT_LISTENER_FACTORY_BEAN_NAME));
}
return beanDefs;
}
i4>: this.scanner = new ClassPathBeanDefinitionScanner(this);创建类路径下的bean定义扫描器
public ClassPathBeanDefinitionScanner(BeanDefinitionRegistry registry, boolean useDefaultFilters,
Environment environment, ResourceLoader resourceLoader) {
Assert.notNull(registry, "BeanDefinitionRegistry must not be null");
this.registry = registry;
// 使用默认的规则
if (useDefaultFilters) {
registerDefaultFilters();
}
// 设置环境
setEnvironment(environment);
// 设置资源加载器
setResourceLoader(resourceLoader);
}
i4.1>: org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider#registerDefaultFilters注册包扫描默认的规则
@SuppressWarnings("unchecked")
protected void registerDefaultFilters() {
this.includeFilters.add(new AnnotationTypeFilter(Component.class));
ClassLoader cl = ClassPathScanningCandidateComponentProvider.class.getClassLoader();
try {
this.includeFilters.add(new AnnotationTypeFilter(
((Class) ClassUtils.forName("javax.annotation.ManagedBean", cl)), false));
logger.debug("JSR-250 'javax.annotation.ManagedBean' found and supported for component scanning");
}
catch (ClassNotFoundException ex) {
// JSR-250 1.1 API (as included in Java EE 6) not available - simply skip.
}
try {
this.includeFilters.add(new AnnotationTypeFilter(
((Class) ClassUtils.forName("javax.inject.Named", cl)), false));
logger.debug("JSR-330 'javax.inject.Named' annotation found and supported for component scanning");
}
catch (ClassNotFoundException ex) {
// JSR-330 API not available - simply skip.
}
}
i5>org.springframework.context.annotation.AnnotatedBeanDefinitionReader#register 使用
i3.1步生成的bean定义读取器注册配置类
public void registerBean(Class annotatedClass, String name, Class... qualifiers) {
AnnotatedGenericBeanDefinition abd = new AnnotatedGenericBeanDefinition(annotatedClass);
if (this.conditionevaluator.shouldSkip(abd.getmetadata())) {
return;
}
Scopemetadata scopemetadata = this.scopemetadataResolver.resolveScopemetadata(abd);
abd.setScope(scopemetadata.getScopeName());
String beanName = (name != null ? name : this.beanNameGenerator.generateBeanName(abd, this.registry));
AnnotationConfigUtils.processCommonDefinitionAnnotations(abd);
if (qualifiers != null) {
for (Class qualifier : qualifiers) {
if (Primary.class == qualifier) {
abd.setPrimary(true);
}
else if (Lazy.class == qualifier) {
abd.setLazyInit(true);
}
else {
abd.addQualifier(new AutowireCandidateQualifier(qualifier));
}
}
}
// 注册自己传入的主配置类bean定义到容器中
BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(abd, beanName);
definitionHolder = AnnotationConfigUtils.applyScopedProxyMode(scopemetadata, definitionHolder, this.registry);
BeanDefinitionReaderUtils.registerBeanDefinition(definitionHolder, this.registry);
}
