[心得体会]Spring容器的初始化
1. Spring容器的初始化过程
public AnnotationConfigApplicationContext(Class<?>... annotatedClasses) {
this();
register(annotatedClasses);
refresh();
}
1. this() 方法的执行过程
(1) 父类构造方法的初始化
1) 在DefaultResourceLoader 类里面初始化创建了个classLoad2) PathMatchingResourcePatternResolver
① 初始化了resourceLoader 属性
② 同时创建了
private PathMatcher pathMatcher = new AntPathMatcher(); 3) GenericApplicationContext类初始化this.beanFactory
public GenericApplicationContext() {
this.beanFactory = new DefaultListableBeanFactory();
}
跟进DefaultListableBeanFactory这个方法
public DefaultListableBeanFactory() { super();}public AbstractAutowireCapableBeanFactory() {
super();
ignoreDependencyInterface(BeanNameAware.class);
ignoreDependencyInterface(BeanFactoryAware.class);
ignoreDependencyInterface(BeanClassLoaderAware.class);
}
上面这个代码主要的功能就是初始化很多属性, 比如Map之类的属性并且忽略了三个Aware
(2) 方法AnnotatedBeanDefinitionReader(this)的执行
public AnnotatedBeanDefinitionReader(BeanDefinitionRegistry registry) {
this(registry, getOrCreateEnvironment(registry));
}
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);
}
public static void registerAnnotationConfigProcessors(BeanDefinitionRegistry registry) {
registerAnnotationConfigProcessors(registry, null);
}
进入上面的方法之后一顿操作就做了两件事情
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());
}
}
初始化了两个对象
DependencyComparator
AutowireCandidateResolver
注册了几个处理器
org.springframework.context.annotation.internalConfigurationAnnotationProcessor
org.springframework.context.annotation.internalAutowiredAnnotationProcessor
org.springframework.context.annotation.internalCommonAnnotationProcessor
org.springframework.context.annotation.internalPersistenceAnnotationProcessor
org.springframework.context.event.internalEventListenerProcessor
org.springframework.context.event.internalEventListenerFactory
(3) 方法ClassPathBeanDefinitionScanner(this)的执行
public ClassPathBeanDefinitionScanner(BeanDefinitionRegistry registry) {
this(registry, true);
}
public ClassPathBeanDefinitionScanner(BeanDefinitionRegistry registry, boolean useDefaultFilters) {
this(registry, useDefaultFilters, getOrCreateEnvironment(registry));
}
public ClassPathBeanDefinitionScanner(BeanDefinitionRegistry registry, boolean useDefaultFilters,
Environment environment) {
this(registry, useDefaultFilters, environment,
(registry instanceof ResourceLoader ? (ResourceLoader) registry : null));
}
public ClassPathBeanDefinitionScanner(BeanDefinitionRegistry registry, boolean useDefaultFilters,
Environment environment, ResourceLoader resourceLoader) {
Assert.notNull(registry, "BeanDefinitionRegistry must not be null");
this.registry = registry;
if (useDefaultFilters) {
// 默认的过滤器
registerDefaultFilters();
}
setEnvironment(environment);
setResourceLoader(resourceLoader);
}
注入默认的类型过滤器
protected void registerDefaultFilters() {
this.includeFilters.add(new AnnotationTypeFilter(Component.class));
ClassLoader cl = ClassPathScanningCandidateComponentProvider.class.getClassLoader();
try {
this.includeFilters.add(new AnnotationTypeFilter(
((Class<? extends Annotation>) ClassUtils.forName("javax.annotation.ManagedBean", cl)), false));
logger.trace("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<? extends Annotation>) ClassUtils.forName("javax.inject.Named", cl)), false));
logger.trace("JSR-330 'javax.inject.Named' annotation found and supported for component scanning");
}
catch (ClassNotFoundException ex) {
// JSR-330 API not available - simply skip.
}
}
2. 配置类的扫描和注册
(1) register(annotatedClasses)注册方式
private final AnnotatedBeanDefinitionReader reader; // bean读取加载器public void register(Class<?>... annotatedClasses) {
Assert.notEmpty(annotatedClasses, "At least one annotated class must be specified");
this.reader.register(annotatedClasses);
}
<T> void doRegisterBean(Class<T> annotatedClass, Supplier<T> instanceSupplier, String name,
Class<? extends Annotation>[] qualifiers, BeanDefinitionCustomizer... definitionCustomizers) {
// 作用: 将Class类保存到abd对象里面, 并且保存了这个配置类中的所以注解
AnnotatedGenericBeanDefinition abd = new AnnotatedGenericBeanDefinition(annotatedClass);
// 判断是否存在condition注解, 是否可以跳过
if (this.conditionEvaluator.shouldSkip(abd.getMetadata())) {
return;
}
abd.setInstanceSupplier(instanceSupplier);
// 解析scope注解
ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(abd);
// 设置这个注解的value
abd.setScope(scopeMetadata.getScopeName());
// 获取beanName名字
String beanName = (name != null ? name : this.beanNameGenerator.generateBeanName(abd, this.registry));
// 判断是否有: lazy Primary dependsOn role description 这些注解
AnnotationConfigUtils.processCommonDefinitionAnnotations(abd);
if (qualifiers != null) {
for (Class<? extends Annotation> qualifier : qualifiers) {
if (Primary.class == qualifier) {
abd.setPrimary(true);
}
else if (Lazy.class == qualifier) {
abd.setLazyInit(true);
}
else {
abd.addQualifier(new AutowireCandidateQualifier(qualifier));
}
}
}
for (BeanDefinitionCustomizer customizer : definitionCustomizers) {
customizer.customize(abd);
}
// 创建BeanDefinitionHolder
BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(abd, beanName);
// 创建代理类
definitionHolder = AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
// 注册beandefinition
BeanDefinitionReaderUtils.registerBeanDefinition(definitionHolder, this.registry);
}
(2) 使用scan(basePackages)实现的注册
public int scan(String... basePackages) {
int beanCountAtScanStart = this.registry.getBeanDefinitionCount();
// 扫描包
doScan(basePackages);
// 这里就是this()方法里面执行的注册的6个类, 不过现在默认不会再初始化了
if (this.includeAnnotationConfig) {
AnnotationConfigUtils.registerAnnotationConfigProcessors(this.registry);
}
return (this.registry.getBeanDefinitionCount() - beanCountAtScanStart);
}
protected Set<BeanDefinitionHolder> doScan(String... basePackages) {
Assert.notEmpty(basePackages, "At least one base package must be specified");
Set<BeanDefinitionHolder> beanDefinitions = new LinkedHashSet<>();
// 这个就是我们 AnnotationConfigApplicationContext ac = new AnnotationConfigApplicationContext("com"); 定义的扫描包的位置, 里面基本上都是配置类
for (String basePackage : basePackages) {
// 扫描出所有我们定义的bean
Set<BeanDefinition> candidates = findCandidateComponents(basePackage);
for (BeanDefinition candidate : candidates) {
// scope 的读取和设置
ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(candidate);
candidate.setScope(scopeMetadata.getScopeName());
// 生成BeanName的名字
String beanName = this.beanNameGenerator.generateBeanName(candidate, this.registry);
if (candidate instanceof AbstractBeanDefinition) {
// 初始化后置处理器
postProcessBeanDefinition((AbstractBeanDefinition) candidate, beanName);
}
if (candidate instanceof AnnotatedBeanDefinition) {
// 判断是否有 lazy dependsOn role description 属性
AnnotationConfigUtils.processCommonDefinitionAnnotations((AnnotatedBeanDefinition) candidate);
}
if (checkCandidate(beanName, candidate)) {
BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(candidate, beanName);
definitionHolder =
AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
// 把BeanDefinition设置到备份的这个对象中, 到时候返回
beanDefinitions.add(definitionHolder);
// 注册BeanDefinition
registerBeanDefinition(definitionHolder, this.registry);
}
}
}
return beanDefinitions;
}
public Set<BeanDefinition> findCandidateComponents(String basePackage) {
if (this.componentsIndex != null && indexSupportsIncludeFilters()) {
return addCandidateComponentsFromIndex(this.componentsIndex, basePackage);
}
else {
return scanCandidateComponents(basePackage);
}
}
private Set<BeanDefinition> scanCandidateComponents(String basePackage) {
Set<BeanDefinition> candidates = new LinkedHashSet<>();
try {
String packageSearchPath = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX +
resolveBasePackage(basePackage) + '/' + this.resourcePattern;
// 获取所有的字节码文件
Resource[] resources = getResourcePatternResolver().getResources(packageSearchPath);
boolean traceEnabled = logger.isTraceEnabled();
boolean debugEnabled = logger.isDebugEnabled();
for (Resource resource : resources) {
if (traceEnabled) {
logger.trace("Scanning " + resource);
}
if (resource.isReadable()) {
try {
MetadataReader metadataReader = getMetadataReaderFactory().getMetadataReader(resource);
if (isCandidateComponent(metadataReader)) {
ScannedGenericBeanDefinition sbd = new ScannedGenericBeanDefinition(metadataReader);
sbd.setResource(resource);
sbd.setSource(resource);
if (isCandidateComponent(sbd)) {
if (debugEnabled) {
logger.debug("Identified candidate component class: " + resource);
}
candidates.add(sbd);
}
else {
if (debugEnabled) {
logger.debug("Ignored because not a concrete top-level class: " + resource);
}
}
}
else {
if (traceEnabled) {
logger.trace("Ignored because not matching any filter: " + resource);
}
}
}
catch (Throwable ex) {
throw new BeanDefinitionStoreException(
"Failed to read candidate component class: " + resource, ex);
}
}
else {
if (traceEnabled) {
logger.trace("Ignored because not readable: " + resource);
}
}
}
}
catch (IOException ex) {
throw new BeanDefinitionStoreException("I/O failure during classpath scanning", ex);
}
return candidates;
}
public Resource[] getResources(String locationPattern) throws IOException {
Assert.notNull(locationPattern, "Location pattern must not be null");
if (locationPattern.startsWith(CLASSPATH_ALL_URL_PREFIX)) {
// a class path resource (multiple resources for same name possible)
if (getPathMatcher().isPattern(locationPattern.substring(CLASSPATH_ALL_URL_PREFIX.length()))) {
// a class path resource pattern
return findPathMatchingResources(locationPattern);
}
else {
// all class path resources with the given name
return findAllClassPathResources(locationPattern.substring(CLASSPATH_ALL_URL_PREFIX.length()));
}
}
else {
// Generally only look for a pattern after a prefix here,
// and on Tomcat only after the "*/" separator for its "war:" protocol.
int prefixEnd = (locationPattern.startsWith("war:") ? locationPattern.indexOf("*/") + 1 :
locationPattern.indexOf(':') + 1);
if (getPathMatcher().isPattern(locationPattern.substring(prefixEnd))) {
// a file pattern
return findPathMatchingResources(locationPattern);
}
else {
// a single resource with the given name
return new Resource[] {getResourceLoader().getResource(locationPattern)};
}
}
}
protected Resource[] findPathMatchingResources(String locationPattern) throws IOException {
String rootDirPath = determineRootDir(locationPattern);
String subPattern = locationPattern.substring(rootDirPath.length());
// 获取包目录
Resource[] rootDirResources = getResources(rootDirPath);
Set<Resource> result = new LinkedHashSet<>(16);
// 遍历包, com.zhazha.dao, com.zhazha.service, com.zhazha.controller
for (Resource rootDirResource : rootDirResources) {
rootDirResource = resolveRootDirResource(rootDirResource);
URL rootDirUrl = rootDirResource.getURL();
if (equinoxResolveMethod != null && rootDirUrl.getProtocol().startsWith("bundle")) {
URL resolvedUrl = (URL) ReflectionUtils.invokeMethod(equinoxResolveMethod, null, rootDirUrl);
if (resolvedUrl != null) {
rootDirUrl = resolvedUrl;
}
rootDirResource = new UrlResource(rootDirUrl);
}
if (rootDirUrl.getProtocol().startsWith(ResourceUtils.URL_PROTOCOL_VFS)) {
result.addAll(VfsResourceMatchingDelegate.findMatchingResources(rootDirUrl, subPattern, getPathMatcher()));
}
else if (ResourceUtils.isJarURL(rootDirUrl) || isJarResource(rootDirResource)) {
result.addAll(doFindPathMatchingJarResources(rootDirResource, rootDirUrl, subPattern));
}
else {
// 遍历出一个包, 放入这个方法进行扫描字节码文件
result.addAll(doFindPathMatchingFileResources(rootDirResource, subPattern));
}
}
if (logger.isTraceEnabled()) {
logger.trace("Resolved location pattern [" + locationPattern + "] to resources " + result);
}
return result.toArray(new Resource[0]);
}
protected Set<Resource> doFindPathMatchingFileResources(Resource rootDirResource, String subPattern)
throws IOException {
File rootDir;
try {
rootDir = rootDirResource.getFile().getAbsoluteFile();
}
catch (FileNotFoundException ex) {
if (logger.isDebugEnabled()) {
logger.debug("Cannot search for matching files underneath " + rootDirResource +
" in the file system: " + ex.getMessage());
}
return Collections.emptySet();
}
catch (Exception ex) {
if (logger.isInfoEnabled()) {
logger.info("Failed to resolve " + rootDirResource + " in the file system: " + ex);
}
return Collections.emptySet();
}
// 遍历com.zhazha.dao这个包里面的.class字节码文件
return doFindMatchingFileSystemResources(rootDir, subPattern);
}
protected Set<Resource> doFindMatchingFileSystemResources(File rootDir, String subPattern) throws IOException {
if (logger.isTraceEnabled()) {
logger.trace("Looking for matching resources in directory tree [" + rootDir.getPath() + "]");
}
// 获得.class字节码文件的列表
Set<File> matchingFiles = retrieveMatchingFiles(rootDir, subPattern);
Set<Resource> result = new LinkedHashSet<>(matchingFiles.size());
// 把发现的所有.class文件的file对象放入result中, 这个result是资源的
for (File file : matchingFiles) {
result.add(new FileSystemResource(file));
}
return result;
}
protected Set<File> retrieveMatchingFiles(File rootDir, String pattern) throws IOException {
if (!rootDir.exists()) {
// Silently skip non-existing directories.
if (logger.isDebugEnabled()) {
logger.debug("Skipping [" + rootDir.getAbsolutePath() + "] because it does not exist");
}
return Collections.emptySet();
}
if (!rootDir.isDirectory()) {
// Complain louder if it exists but is no directory.
if (logger.isInfoEnabled()) {
logger.info("Skipping [" + rootDir.getAbsolutePath() + "] because it does not denote a directory");
}
return Collections.emptySet();
}
if (!rootDir.canRead()) {
if (logger.isInfoEnabled()) {
logger.info("Skipping search for matching files underneath directory [" + rootDir.getAbsolutePath() +
"] because the application is not allowed to read the directory");
}
return Collections.emptySet();
}
String fullPattern = StringUtils.replace(rootDir.getAbsolutePath(), File.separator, "/");
if (!pattern.startsWith("/")) {
fullPattern += "/";
}
fullPattern = fullPattern + StringUtils.replace(pattern, File.separator, "/");
Set<File> result = new LinkedHashSet<>(8);
// 匹配字节码文件.class, 将结果放入result
doRetrieveMatchingFiles(fullPattern, rootDir, result);
return result;
}
protected void doRetrieveMatchingFiles(String fullPattern, File dir, Set<File> result) throws IOException {
if (logger.isTraceEnabled()) {
logger.trace("Searching directory [" + dir.getAbsolutePath() +
"] for files matching pattern [" + fullPattern + "]");
}
// 获取包下面的所有文件, 不断的遍历直到找到.class
for (File content : listDirectory(dir)) {
String currPath = StringUtils.replace(content.getAbsolutePath(), File.separator, "/");
if (content.isDirectory() && getPathMatcher().matchStart(fullPattern, currPath + "/")) {
// 不可读的话
if (!content.canRead()) {
if (logger.isDebugEnabled()) {
logger.debug("Skipping subdirectory [" + dir.getAbsolutePath() +
"] because the application is not allowed to read the directory");
}
}
else {
// 回调方法
doRetrieveMatchingFiles(fullPattern, content, result);
}
}
// 把找到的.class字节码放入结果中
if (getPathMatcher().match(fullPattern, currPath)) {
result.add(content);
}
}
}
3. refresh方法详情
总共分为13个步骤
@Override
public void refresh() throws BeansException, IllegalStateException {
synchronized (this.startupShutdownMonitor) {
// 准备此上下文以进行刷新。
prepareRefresh();
// 告诉子类刷新内部bean工厂。
ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
// 准备在这种情况下使用的bean工厂。
prepareBeanFactory(beanFactory);
try {
// 允许在上下文子类中对bean工厂进行后处理。(但是里面的方法是空的)
postProcessBeanFactory(beanFactory);
// 调用在上下文中注册为bean的工厂处理器。
invokeBeanFactoryPostProcessors(beanFactory);
// 注册拦截Bean创建的Bean处理器。
registerBeanPostProcessors(beanFactory);
// 为此上下文初始化消息源。
initMessageSource();
// 为此上下文初始化事件多播器。
initApplicationEventMulticaster();
// 在特定上下文子类中初始化其他特殊bean。
onRefresh();
// 检查侦听器bean并注册它们。
registerListeners();
// 实例化所有剩余的（非延迟初始化）单例。
finishBeanFactoryInitialization(beanFactory);
// 最后一步：发布相应的事件。
finishRefresh();
}
catch (BeansException ex) {
if (logger.isWarnEnabled()) {
logger.warn("Exception encountered during context initialization - " +
"cancelling refresh attempt: " + ex);
}
// 销毁已创建的单例以避免资源悬空。
destroyBeans();
// 重置“活动”标志。
cancelRefresh(ex);
// 将异常传播给呼叫者。
throw ex;
}
finally {
// 在Spring的核心中重置常见的自省缓存，因为我们可能再也不需要单例bean的元数据了。
resetCommonCaches();
}
}
}
(1) 准备此上下文以进行刷新
protected void prepareRefresh() {
// 获取spring容器开启时间
this.startupDate = System.currentTimeMillis();
// 标记closed属性为false
this.closed.set(false);
// 激活标志为true
this.active.set(true);
if (logger.isDebugEnabled()) {
if (logger.isTraceEnabled()) {
logger.trace("Refreshing " + this);
}
else {
logger.debug("Refreshing " + getDisplayName());
}
}
// 在上下文环境中初始化任何占位符属性源
initPropertySources();
// 验证所有标记为必需的属性都是可解析的:
// see ConfigurablePropertyResolver#setRequiredProperties
getEnvironment().validateRequiredProperties();
// 存储预刷新应用程序 / 监听器..。
if (this.earlyApplicationListeners == null) {
this.earlyApplicationListeners = new LinkedHashSet<>(this.applicationListeners);
}
else {
// 将本地应用程序侦听器重置为预刷新状态。
this.applicationListeners.clear();
this.applicationListeners.addAll(this.earlyApplicationListeners);
}
// 允许收集早期应用程序事件，以便在多管道可用时发布..。
this.earlyApplicationEvents = new LinkedHashSet<>();
}
添加监听器
(2) 告诉子类刷新内部bean工厂
protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {
// 产生id
refreshBeanFactory();
return getBeanFactory();
}
里面就这一句话
this.beanFactory.setSerializationId(getId());
(3) 准备在这种情况下使用的bean工厂
protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
// 告诉内部 bean 工厂使用上下文的类装入器等
beanFactory.setBeanClassLoader(getClassLoader());
beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));
// 使用上下文回调配置 bean 工厂
beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
beanFactory.ignoreDependencyInterface(EnvironmentAware.class);
beanFactory.ignoreDependencyInterface(EmbeddedValueResolverAware.class);
beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class);
beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class);
beanFactory.ignoreDependencyInterface(MessageSourceAware.class);
beanFactory.ignoreDependencyInterface(ApplicationContextAware.class);
// 在普通工厂中，BeanFactory 接口未注册为可解析类型。
// Messagesource 以 bean 的形式注册(并在自动装配中找到)。
beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory);
beanFactory.registerResolvableDependency(ResourceLoader.class, this);
beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this);
beanFactory.registerResolvableDependency(ApplicationContext.class, this);
// 将检测内部 bean 的早期后处理程序注册为 ApplicationListeners。
beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(this));
// 检测 LoadTimeWeaver 并准备编织(如果发现)。
if (beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
// 设置用于类型匹配的临时 ClassLoader。
beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
}
// 注册默认环境 bean。
if (!beanFactory.containsLocalBean(ENVIRONMENT_BEAN_NAME)) {
beanFactory.registerSingleton(ENVIRONMENT_BEAN_NAME, getEnvironment());
}
if (!beanFactory.containsLocalBean(SYSTEM_PROPERTIES_BEAN_NAME)) {
beanFactory.registerSingleton(SYSTEM_PROPERTIES_BEAN_NAME, getEnvironment().getSystemProperties());
}
if (!beanFactory.containsLocalBean(SYSTEM_ENVIRONMENT_BEAN_NAME)) {
beanFactory.registerSingleton(SYSTEM_ENVIRONMENT_BEAN_NAME, getEnvironment().getSystemEnvironment());
}
}
(4) 允许在上下文子类中对bean工厂进行后处理。(但是里面的方法是空的)
内部方法为空
(5) 调用在上下文中注册为bean的工厂后置处理器
invokeBeanFactoryPostProcessors(beanFactory);
protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
// 传入beanFactory和所有的PostProcessors, 进行PostProcessors的注册
PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors());
// Detect a LoadTimeWeaver and prepare for weaving, if found in the meantime
// (e.g. through an @Bean method registered by ConfigurationClassPostProcessor)
if (beanFactory.getTempClassLoader() == null && beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
}
}
把注解放入List<BeanDefinitionHolder> configCandidates = new ArrayList<>();
// 配置类的解析读取器: 解析ComponeScan注解扫描的所有bean ConfigurationClassParser parser = new ConfigurationClassParser( this.metadataReaderFactory, this.problemReporter, this.environment, this.resourceLoader, this.componentScanBeanNameGenerator, registry);
// 这里开始真正的解析 parser.parse(candidates);
最终解析完毕之后会把对象放入parser的configurationClasses属性之中
public void parse(Set<BeanDefinitionHolder> configCandidates) {
for (BeanDefinitionHolder holder : configCandidates) {
BeanDefinition bd = holder.getBeanDefinition();
try {
if (bd instanceof AnnotatedBeanDefinition) {
// 我们的这个案例最终往这里走
parse(((AnnotatedBeanDefinition) bd).getMetadata(), holder.getBeanName());
}
else if (bd instanceof AbstractBeanDefinition && ((AbstractBeanDefinition) bd).hasBeanClass()) {
parse(((AbstractBeanDefinition) bd).getBeanClass(), holder.getBeanName());
}
else {
parse(bd.getBeanClassName(), holder.getBeanName());
}
}
catch (BeanDefinitionStoreException ex) {
throw ex;
}
catch (Throwable ex) {
throw new BeanDefinitionStoreException(
"Failed to parse configuration class [" + bd.getBeanClassName() + "]", ex);
}
}
this.deferredImportSelectorHandler.process();
}
protected void processConfigurationClass(ConfigurationClass configClass) throws IOException {
// 检测条件判断
if (this.conditionEvaluator.shouldSkip(configClass.getMetadata(), ConfigurationPhase.PARSE_CONFIGURATION)) {
return;
}
// 判断容器是否已经存在这个配置类
ConfigurationClass existingClass = this.configurationClasses.get(configClass);
if (existingClass != null) {
if (configClass.isImported()) {
if (existingClass.isImported()) {
// 合并
existingClass.mergeImportedBy(configClass);
}
// Otherwise ignore new imported config class; existing non-imported class overrides it.
return;
}
else {
// Explicit bean definition found, probably replacing an import.
// Let's remove the old one and go with the new one.
this.configurationClasses.remove(configClass);
this.knownSuperclasses.values().removeIf(configClass::equals);
}
}
// 递归地处理配置类及其超类层次结构.
SourceClass sourceClass = asSourceClass(configClass);
do {
sourceClass = doProcessConfigurationClass(configClass, sourceClass);
}
while (sourceClass != null);
this.configurationClasses.put(configClass, configClass);
}
// 处理任何@componentscan 注释
Set<AnnotationAttributes> componentScans = AnnotationConfigUtils.attributesForRepeatable(
sourceClass.getMetadata(), ComponentScans.class, ComponentScan.class);
if (!componentScans.isEmpty() &&
!this.conditionEvaluator.shouldSkip(sourceClass.getMetadata(), ConfigurationPhase.REGISTER_BEAN)) {
for (AnnotationAttributes componentScan : componentScans) {
// 配置类使用@componentscan 注释——立即执行扫描
Set<BeanDefinitionHolder> scannedBeanDefinitions =
this.componentScanParser.parse(componentScan, sourceClass.getMetadata().getClassName());
// 检查任何进一步配置类的扫描定义集，并在需要时递归地解析
for (BeanDefinitionHolder holder : scannedBeanDefinitions) {
BeanDefinition bdCand = holder.getBeanDefinition().getOriginatingBeanDefinition();
if (bdCand == null) {
bdCand = holder.getBeanDefinition();
}
if (ConfigurationClassUtils.checkConfigurationClassCandidate(bdCand, this.metadataReaderFactory)) {
parse(bdCand.getBeanClassName(), holder.getBeanName());
}
}
}
}
public Set<BeanDefinitionHolder> parse(AnnotationAttributes componentScan, final String declaringClass) {
// 类扫描工具
ClassPathBeanDefinitionScanner scanner = new ClassPathBeanDefinitionScanner(this.registry,
componentScan.getBoolean("useDefaultFilters"), this.environment, this.resourceLoader);
Class<? extends BeanNameGenerator> generatorClass = componentScan.getClass("nameGenerator");
boolean useInheritedGenerator = (BeanNameGenerator.class == generatorClass);
scanner.setBeanNameGenerator(useInheritedGenerator ? this.beanNameGenerator :
BeanUtils.instantiateClass(generatorClass));
ScopedProxyMode scopedProxyMode = componentScan.getEnum("scopedProxy");
if (scopedProxyMode != ScopedProxyMode.DEFAULT) {
scanner.setScopedProxyMode(scopedProxyMode);
}
else {
Class<? extends ScopeMetadataResolver> resolverClass = componentScan.getClass("scopeResolver");
scanner.setScopeMetadataResolver(BeanUtils.instantiateClass(resolverClass));
}
// 获取扫描包路径的.class字节码文件
scanner.setResourcePattern(componentScan.getString("resourcePattern"));
// 添加包括类型过滤器
for (AnnotationAttributes filter : componentScan.getAnnotationArray("includeFilters")) {
for (TypeFilter typeFilter : typeFiltersFor(filter)) {
scanner.addIncludeFilter(typeFilter);
}
}
// 添加排除类型过滤器
for (AnnotationAttributes filter : componentScan.getAnnotationArray("excludeFilters")) {
for (TypeFilter typeFilter : typeFiltersFor(filter)) {
scanner.addExcludeFilter(typeFilter);
}
}
// 设置懒加载状态
boolean lazyInit = componentScan.getBoolean("lazyInit");
if (lazyInit) {
scanner.getBeanDefinitionDefaults().setLazyInit(true);
}
// 把包componentScan扫描获取的Bean全部放入这个对象中
Set<String> basePackages = new LinkedHashSet<>();
// 获取componentScan扫描包路径的表达式
String[] basePackagesArray = componentScan.getStringArray("basePackages");
for (String pkg : basePackagesArray) {
String[] tokenized = StringUtils.tokenizeToStringArray(this.environment.resolvePlaceholders(pkg),
ConfigurableApplicationContext.CONFIG_LOCATION_DELIMITERS);
Collections.addAll(basePackages, tokenized);
}
for (Class<?> clazz : componentScan.getClassArray("basePackageClasses")) {
basePackages.add(ClassUtils.getPackageName(clazz));
}
if (basePackages.isEmpty()) {
// 获取本类位置的package包的路径
basePackages.add(ClassUtils.getPackageName(declaringClass));
}
// 排除掉本类的路径, 防止重复注册
scanner.addExcludeFilter(new AbstractTypeHierarchyTraversingFilter(false, false) {
@Override
protected boolean matchClassName(String className) {
return declaringClass.equals(className);
}
});
// 做扫描, 返回注解扫描出来的所有类, 并且注册扫描出来的组件到容器中
return scanner.doScan(StringUtils.toStringArray(basePackages));
}
private Set<BeanDefinition> scanCandidateComponents(String basePackage) {
Set<BeanDefinition> candidates = new LinkedHashSet<>();
try {
// 组装 com.**.class
String packageSearchPath = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX +
resolveBasePackage(basePackage) + '/' + this.resourcePattern;
// 获取所有子类的class字节码
Resource[] resources = getResourcePatternResolver().getResources(packageSearchPath);
boolean traceEnabled = logger.isTraceEnabled();
boolean debugEnabled = logger.isDebugEnabled();
// 遍历所有字节码文件资源
for (Resource resource : resources) {
if (traceEnabled) {
logger.trace("Scanning " + resource);
}
if (resource.isReadable()) {
try {
MetadataReader metadataReader = getMetadataReaderFactory().getMetadataReader(resource);
if (isCandidateComponent(metadataReader)) {
ScannedGenericBeanDefinition sbd = new ScannedGenericBeanDefinition(metadataReader);
sbd.setResource(resource);
sbd.setSource(resource);
if (isCandidateComponent(sbd)) {
if (debugEnabled) {
logger.debug("Identified candidate component class: " + resource);
}
candidates.add(sbd);
}
else {
if (debugEnabled) {
logger.debug("Ignored because not a concrete top-level class: " + resource);
}
}
}
else {
if (traceEnabled) {
logger.trace("Ignored because not matching any filter: " + resource);
}
}
}
catch (Throwable ex) {
throw new BeanDefinitionStoreException(
"Failed to read candidate component class: " + resource, ex);
}
}
else {
if (traceEnabled) {
logger.trace("Ignored because not readable: " + resource);
}
}
}
}
catch (IOException ex) {
throw new BeanDefinitionStoreException("I/O failure during classpath scanning", ex);
}
return candidates;
}
protected Set<BeanDefinitionHolder> doScan(String... basePackages) {
Assert.notEmpty(basePackages, "At least one base package must be specified");
// 将我们需要扫描到的类加入到这里, 比如UserDao这种
Set<BeanDefinitionHolder> beanDefinitions = new LinkedHashSet<>();
// 遍历前面获取的所有.class字节码文件的路径
for (String basePackage : basePackages) {
// 判断是否是我们需要的组件, 比如UserDao UserService UserController 这种, 不包括配置类
Set<BeanDefinition> candidates = findCandidateComponents(basePackage);
for (BeanDefinition candidate : candidates) {
// 获取scope, 并且设置scope
ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(candidate);
candidate.setScope(scopeMetadata.getScopeName());
// 获取bean的名字, 这里的名字不包含包名
String beanName = this.beanNameGenerator.generateBeanName(candidate, this.registry);
// 设置默认Beandefinition的默认属性, 例如lazy InitMethodName AutowireMode DestroyMethodName 这类属性
if (candidate instanceof AbstractBeanDefinition) {
postProcessBeanDefinition((AbstractBeanDefinition) candidate, beanName);
}
if (candidate instanceof AnnotatedBeanDefinition) {
// 设置lazy Primary dependsOn role description
AnnotationConfigUtils.processCommonDefinitionAnnotations((AnnotatedBeanDefinition) candidate);
}
if (checkCandidate(beanName, candidate)) {
BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(candidate, beanName);
definitionHolder =
AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
beanDefinitions.add(definitionHolder);
// 注册UserDao这样的组件
registerBeanDefinition(definitionHolder, this.registry);
}
}
}
return beanDefinitions;
}
(6) 注册拦截Bean创建的Bean处理器
注册bean的后置处理器
registerBeanPostProcessors(beanFactory)
org.springframework.context.support.PostProcessorRegistrationDelegate#registerBeanPostProcessors(org.springframework.beans.factory.config.ConfigurableListableBeanFactory, org.springframework.context.support.AbstractApplicationContext)
protected void registerBeanPostProcessors(ConfigurableListableBeanFactory beanFactory) {
// 这个beanFactory就是DefaultListableBeanFactory, 这个this就是AnnotationConfigApplicationContext
PostProcessorRegistrationDelegate.registerBeanPostProcessors(beanFactory, this);
}
注册PostProcessors
// 根据类型获取容器中的postProcessor String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false);
根据不同PostProcessor继承的接口把不同的PostProcess放入不同的集合
List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
List<BeanPostProcessor> internalPostProcessors = new ArrayList<>();
List<String> orderedPostProcessorNames = new ArrayList<>();
List<String> nonOrderedPostProcessorNames = new ArrayList<>();
for (String ppName : postProcessorNames) {
if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
priorityOrderedPostProcessors.add(pp);
if (pp instanceof MergedBeanDefinitionPostProcessor) {
internalPostProcessors.add(pp);
}
}
else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
orderedPostProcessorNames.add(ppName);
}
else {
nonOrderedPostProcessorNames.add(ppName);
}
}
// 注册继承了priority的PostProcessor registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);
// 注册实现了Ordered的PostProcessor
List<BeanPostProcessor> orderedPostProcessors = new ArrayList<>();
for (String ppName : orderedPostProcessorNames) {
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
orderedPostProcessors.add(pp);
if (pp instanceof MergedBeanDefinitionPostProcessor) {
internalPostProcessors.add(pp);
}
}
sortPostProcessors(orderedPostProcessors, beanFactory);
registerBeanPostProcessors(beanFactory, orderedPostProcessors);
// 注册所有常规的PostProcessor
List<BeanPostProcessor> nonOrderedPostProcessors = new ArrayList<>();
for (String ppName : nonOrderedPostProcessorNames) {
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
nonOrderedPostProcessors.add(pp);
if (pp instanceof MergedBeanDefinitionPostProcessor) {
internalPostProcessors.add(pp);
}
}
registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors);
// 注册内部类 sortPostProcessors(internalPostProcessors, beanFactory); registerBeanPostProcessors(beanFactory, internalPostProcessors); // 将检测内部 bean 的后处理器重新注册为 ApplicationListeners，将其移动到处理器链的末尾(用于接收代理等)。 beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));
(7) 为此上下文初始化消息源
initMessageSource();
内部做了个消息源的单例的注册
(8) 为此上下文初始化事件多播器
this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory); beanFactory.registerSingleton(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, this.applicationEventMulticaster);
(9) 在特定上下文子类中初始化其他特殊bean
protected void onRefresh() throws BeansException {
// For subclasses: do nothing by default.
}
(10) 检查侦听器bean并注册它们
registerListeners();
protected void registerListeners() {
// 先注册静态指定的侦听器。
for (ApplicationListener<?> listener : getApplicationListeners()) {
getApplicationEventMulticaster().addApplicationListener(listener);
}
// 不要在这里初始化 FactoryBeans: 我们需要保留所有未初始化的常规 beans，以便将后处理器应用于它们！
// 这里其实就是拿到application中的监听器
String[] listenerBeanNames = getBeanNamesForType(ApplicationListener.class, true, false);
for (String listenerBeanName : listenerBeanNames) {
getApplicationEventMulticaster().addApplicationListenerBean(listenerBeanName);
}
// 发布早期的应用程序事件，现在我们终于有了一个多主机..
Set<ApplicationEvent> earlyEventsToProcess = this.earlyApplicationEvents;
this.earlyApplicationEvents = null;
if (earlyEventsToProcess != null) {
for (ApplicationEvent earlyEvent : earlyEventsToProcess) {
getApplicationEventMulticaster().multicastEvent(earlyEvent);
}
}
}
(11) 实例化所有剩余的（非延迟初始化）单例
finishBeanFactoryInitialization(beanFactory);
beanFactory.preInstantiateSingletons(); // 里面最重要的方法
public void preInstantiateSingletons() throws BeansException {
if (logger.isTraceEnabled()) {
logger.trace("Pre-instantiating singletons in " + this);
}
// Iterate over a copy to allow for init methods which in turn register new bean definitions.
// While this may not be part of the regular factory bootstrap, it does otherwise work fine.
// 里面存入beandefinition的名字
List<String> beanNames = new ArrayList<>(this.beanDefinitionNames);
// Trigger initialization of all non-lazy singleton beans...
// 遍历这个definitionBean的名字
for (String beanName : beanNames) {
// 获取BeanDefinition
RootBeanDefinition bd = getMergedLocalBeanDefinition(beanName);
if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) {
// 是工厂类么?
if (isFactoryBean(beanName)) {
// 根据完整的包名获取对象 FACTORY_BEAN_PREFIX = &
Object bean = getBean(FACTORY_BEAN_PREFIX + beanName);
if (bean instanceof FactoryBean) {
final FactoryBean<?> factory = (FactoryBean<?>) bean;
boolean isEagerInit;
if (System.getSecurityManager() != null && factory instanceof SmartFactoryBean) {
isEagerInit = AccessController.doPrivileged((PrivilegedAction<Boolean>)
((SmartFactoryBean<?>) factory)::isEagerInit,
getAccessControlContext());
}
else {
isEagerInit = (factory instanceof SmartFactoryBean &&
((SmartFactoryBean<?>) factory).isEagerInit());
}
if (isEagerInit) {
getBean(beanName);
}
}
}
else {
// 根据这个bean获取对象, 如果没有则创建这个bean
getBean(beanName);
}
}
}
// 触发所有适用bean的初始化后回调...
for (String beanName : beanNames) {
Object singletonInstance = getSingleton(beanName);
if (singletonInstance instanceof SmartInitializingSingleton) {
final SmartInitializingSingleton smartSingleton = (SmartInitializingSingleton) singletonInstance;
if (System.getSecurityManager() != null) {
AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
smartSingleton.afterSingletonsInstantiated();
return null;
}, getAccessControlContext());
}
else {
smartSingleton.afterSingletonsInstantiated();
}
}
}
}
