目錄
- 1. Bean的實例化概述
- 2. 流程概覽
- 3. 源碼分析
- 4. 演示
- 4. 總結
爲源碼付出的每一分努力都不會白費。
1. Bean的實例化概述
前一篇分析了BeanDefinition的封裝過程，最終將beanName與BeanDefinition以一對一映射關係放到beanDefinitionMap容器中，這一篇重點分析如何利用bean的定義信息BeanDefinition實例化bean。
2. 流程概覽
其實bean的實例化過程比較複雜，中間細節很多，爲了抓住重點，先將核心流程梳理出來，主要包含以下幾個流程：
step1: 通過反射創建實例；
step2：給實例屬性賦初始值；
step3：如果Bean類實現BeanNameAware接口，則將通過傳遞Bean的名稱來調用setBeanName()方法；如果Bean類實現BeanClassLoaderAware接口，則將通過傳遞加載此Bean的ClassLoader對象的實例來調用setBeanClassLoader()方法；如果Bean類實現BeanFactoryAware接口，則將通過傳遞BeanFactory對象的實例來調用setBeanFactory()方法；
step4: 如果有類實現BeanPostProcessors接口，則將在初始化之前調用postProcessBeforeInitialization()方法；
step5：如果Bean類實現了InitializingBean接口，將調用afterPropertiesSet()方法，如果配置文件中的Bean定義包含init-method屬性，則該屬性的值將解析爲Bean類中的方法名稱，並將調用該方法；
step6: 如果有類實現BeanPostProcessors接口，則將在初始化之後調用postProcessAfterInitialization()方法；
step7：如果Bean類實現DisposableBean接口，則當Application不再需要Bean引用時，將調用destroy()方法；如果配置文件中的Bean定義包含destroy-method屬性，那麼將調用Bean類中的相應方法定義。
3. 源碼分析
進入AbstractApplicationContext中的fresh()方法，找到finishBeanFactoryInitialization(beanFactory)方法，該類是bean的實例化的入口，具體的實例化由preInstantiateSingletons()方法觸發，見如下代碼：
<code-box id="xHFQpn" style="padding: 0px; margin: 10px 0px; color: rgb(34, 34, 34); font-family: -apple-system, "SF UI Text", Arial, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "WenQuanYi Micro Hei", sans-serif; font-size: 15.5px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgba(255, 255, 255, 0.9); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; position: relative; display: block;"><pre id="pre-xHFQpn" class="hljs armasm mCustomScrollbar _mCS_1 mCS-autoHide" style="padding: 10px !important; margin: 5px 15px; overflow: visible; display: block; background: rgb(43, 43, 43); color: rgb(248, 248, 242); touch-action: pinch-zoom; font-size: 14px !important; font-weight: 400; font-family: "Ubuntu Mono", monospace !important; white-space: pre; overflow-wrap: normal; border-radius: 5px !important; word-break: break-all; counter-reset: itemcounter 0; line-height: 1.5 !important; position: relative;">
<code-pre class="code-pre" id="pre-dCT6nD" style="padding: 0px 0px 0px 10px; margin: 0px; position: relative; display: block; left: 30px; border-left: 1px solid rgb(153, 153, 153);">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.
//xml解析時，把所有beanName都緩存到beanDefinitionNames了 List<String> beanNames = new ArrayList<>(this.beanDefinitionNames);
// Trigger initialization of all non-lazy singleton beans... for (String beanName : beanNames) {
//把父BeanDefinition裏面的屬性拿到子BeanDefinition中 RootBeanDefinition bd = getMergedLocalBeanDefinition(beanName); //如果不是抽象的，單例的，非懶加載的就實例化
if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) {
//判斷bean是否實現了FactoryBean接口 if (isFactoryBean(beanName)) {
Object bean = getBean(FACTORY_BEAN_PREFIX + beanName); if (bean instanceof FactoryBean) {
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 {
// 實例化過程
getBean(beanName); }
}
}</code-pre>
</pre></code-box>
上述代碼主要看getBean方法，隨後進入doGetBean方法:
<code-box id="iaxDFz" style="padding: 0px; margin: 10px 0px; color: rgb(34, 34, 34); font-family: -apple-system, "SF UI Text", Arial, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "WenQuanYi Micro Hei", sans-serif; font-size: 15.5px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgba(255, 255, 255, 0.9); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; position: relative; display: block;"><pre id="pre-iaxDFz" class="hljs pgsql mCustomScrollbar _mCS_2 mCS-autoHide" style="padding: 10px !important; margin: 5px 15px; overflow: visible; display: block; background: rgb(43, 43, 43); color: rgb(248, 248, 242); touch-action: pinch-zoom; font-size: 14px !important; font-weight: 400; font-family: "Ubuntu Mono", monospace !important; white-space: pre; overflow-wrap: normal; border-radius: 5px !important; word-break: break-all; counter-reset: itemcounter 0; line-height: 1.5 !important; position: relative;">
<code-pre class="code-pre" id="pre-QA78ZG" style="padding: 0px 0px 0px 10px; margin: 0px; position: relative; display: block; left: 30px; border-left: 1px solid rgb(153, 153, 153);">protected <T> T doGetBean(
String name, @Nullable Class<T> requiredType, @Nullable Object[] args, boolean typeCheckOnly)
throws BeansException {
String beanName = transformedBeanName(name);
Object bean;
// 從緩存中獲取bean.
Object sharedInstance = getSingleton(beanName);
if (sharedInstance != null && args == null) {
if (logger.isTraceEnabled()) {
if (isSingletonCurrentlyInCreation(beanName)) {
logger.trace("Returning eagerly cached instance of singleton bean '" + beanName +
"' that is not fully initialized yet - a consequence of a circular reference");
}
else {
logger.trace("Returning cached instance of singleton bean '" + beanName + "'");
}
}
bean = getObjectForBeanInstance(sharedInstance, name, beanName, null);
}
else {
// Fail if we're already creating this bean instance: // We're assumably within a circular reference.
if (isPrototypeCurrentlyInCreation(beanName)) {
throw new BeanCurrentlyInCreationException(beanName);
}
// Check if bean definition exists in this factory.
BeanFactory parentBeanFactory = getParentBeanFactory();
if (parentBeanFactory != null && !containsBeanDefinition(beanName)) {
// Not found -> check parent.
String nameToLookup = originalBeanName(name);
if (parentBeanFactory instanceof AbstractBeanFactory) {
return ((AbstractBeanFactory) parentBeanFactory).doGetBean(
nameToLookup, requiredType, args, typeCheckOnly);
}
else if (args != null) {
// Delegation to parent with explicit args.
return (T) parentBeanFactory.getBean(nameToLookup, args);
}
else if (requiredType != null) {
// No args -> delegate to standard getBean method.
return parentBeanFactory.getBean(nameToLookup, requiredType);
}
else {
return (T) parentBeanFactory.getBean(nameToLookup);
}
}
if (!typeCheckOnly) {
markBeanAsCreated(beanName);
}
try {
RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName);
checkMergedBeanDefinition(mbd, beanName, args);
// Guarantee initialization of beans that the current bean depends on.
String[] dependsOn = mbd.getDependsOn();
if (dependsOn != null) {
for (String dep : dependsOn) {
if (isDependent(beanName, dep)) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName,
"Circular depends-on relationship between '" + beanName + "' and '" + dep + "'");
}
registerDependentBean(dep, beanName);
try {
getBean(dep);
}
catch (NoSuchBeanDefinitionException ex) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName,
"'" + beanName + "' depends on missing bean '" + dep + "'", ex);
}
}
}
// Create bean instance
// 創建bean實例
if (mbd.isSingleton()) {
sharedInstance = getSingleton(beanName, () -> {
try {
return createBean(beanName, mbd, args);
}
catch (BeansException ex) {
// Explicitly remove instance from singleton cache: It might have been put there
// eagerly by the creation process, to allow for circular reference resolution.
// Also remove any beans that received a temporary reference to the bean.
destroySingleton(beanName);
throw ex;
}
});
bean = getObjectForBeanInstance(sharedInstance, name, beanName, mbd);
}
...
}</code-pre>
</pre></code-box>
由上述代碼可知，先從緩存中獲取bean，如果沒有，則創建bean，最重要的方法就是getSingleton，該方法第二個參數是個函數式接口，進入getSingleton方法，當調用singletonObject = singletonFactory.getObject()時，會觸發函數式接口中的createBean方法，隨後一路進入doCreateBean，這個方法裏面完成了所有實例化所需的步驟:
<code-box id="fmyDEp" style="padding: 0px; margin: 10px 0px; color: rgb(34, 34, 34); font-family: -apple-system, "SF UI Text", Arial, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "WenQuanYi Micro Hei", sans-serif; font-size: 15.5px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgba(255, 255, 255, 0.9); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; position: relative; display: block;"><pre id="pre-fmyDEp" class="hljs processing mCustomScrollbar _mCS_3 mCS-autoHide" style="padding: 10px !important; margin: 5px 15px; overflow: visible; display: block; background: rgb(43, 43, 43); color: rgb(248, 248, 242); touch-action: pinch-zoom; font-size: 14px !important; font-weight: 400; font-family: "Ubuntu Mono", monospace !important; white-space: pre; overflow-wrap: normal; border-radius: 5px !important; word-break: break-all; counter-reset: itemcounter 0; line-height: 1.5 !important; position: relative;">
<code-pre class="code-pre" id="pre-ZEZrYQ" style="padding: 0px 0px 0px 10px; margin: 0px; position: relative; display: block; left: 30px; border-left: 1px solid rgb(153, 153, 153);">protected Object doCreateBean(String beanName, RootBeanDefinition mbd, @Nullable Object[] args)
throws BeanCreationException {
// Instantiate the bean.
// 真正開始創建bean的實例.
BeanWrapper instanceWrapper = null;
if (mbd.isSingleton()) {
instanceWrapper = this.factoryBeanInstanceCache.remove(beanName);
}
if (instanceWrapper == null) {
instanceWrapper = createBeanInstance(beanName, mbd, args);
}
Object bean = instanceWrapper.getWrappedInstance();
Class<?> beanType = instanceWrapper.getWrappedClass();
if (beanType != NullBean.class) {
mbd.resolvedTargetType = beanType;
}
// Allow post-processors to modify the merged bean definition.
synchronized (mbd.postProcessingLock) {
if (!mbd.postProcessed) {
try {
applyMergedBeanDefinitionPostProcessors(mbd, beanType, beanName);
}
catch (Throwable ex) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName,
"Post-processing of merged bean definition failed", ex);
}
mbd.postProcessed = true;
}
}
// Eagerly cache singletons to be able to resolve circular references
// even when triggered by lifecycle interfaces like BeanFactoryAware.
boolean earlySingletonExposure = (mbd.isSingleton() && this.allowCircularReferences &&
isSingletonCurrentlyInCreation(beanName));
if (earlySingletonExposure) {
if (logger.isTraceEnabled()) {
logger.trace("Eagerly caching bean '" + beanName +
"' to allow for resolving potential circular references");
}
addSingletonFactory(beanName, () -> getEarlyBeanReference(beanName, mbd, bean));
}
// Initialize the bean instance.
Object exposedObject = bean;
try {
// 屬性賦值
populateBean(beanName, mbd, instanceWrapper);
// 初始化bean
exposedObject = initializeBean(beanName, exposedObject, mbd);
}
catch (Throwable ex) {
if (ex instanceof BeanCreationException && beanName.equals(((BeanCreationException) ex).getBeanName())) {
throw (BeanCreationException) ex;
}
else {
throw new BeanCreationException(
mbd.getResourceDescription(), beanName, "Initialization of bean failed", ex);
}
}
if (earlySingletonExposure) {
Object earlySingletonReference = getSingleton(beanName, false);
if (earlySingletonReference != null) {
if (exposedObject == bean) {
exposedObject = earlySingletonReference;
}
else if (!this.allowRawInjectionDespiteWrapping && hasDependentBean(beanName)) {
String[] dependentBeans = getDependentBeans(beanName);
Set<String> actualDependentBeans = new LinkedHashSet<>(dependentBeans.length);
for (String dependentBean : dependentBeans) {
if (!removeSingletonIfCreatedForTypeCheckOnly(dependentBean)) {
actualDependentBeans.add(dependentBean);
}
}
if (!actualDependentBeans.isEmpty()) {
throw new BeanCurrentlyInCreationException(beanName,
"Bean with name '" + beanName + "' has been injected into other beans [" +
StringUtils.collectionToCommaDelimitedString(actualDependentBeans) +
"] in its raw version as part of a circular reference, but has eventually been " +
"wrapped. This means that said other beans do not use the final version of the " +
"bean. This is often the result of over-eager type matching - consider using " +
"'getBeanNamesForType' with the 'allowEagerInit' flag turned off, for example.");
}
}
}
}
// Register bean as disposable.
// 有必要時，註冊bean的銷燬
try {
registerDisposableBeanIfNecessary(beanName, bean, mbd);
}
catch (BeanDefinitionValidationException ex) {
throw new BeanCreationException(
mbd.getResourceDescription(), beanName, "Invalid destruction signature", ex);
}
return exposedObject;
}</code-pre>
</pre></code-box>
從上述源碼中看出bean的實例化主要分爲以下三步：
step1:bean的創建；
step2:給bean的屬性賦值；
step3:bean的初始化；
接着得到exposedObject這個已經完全實例化後的bean返回，其中當有必要時，註冊bean的銷燬，後面再詳細看，先抓住主要流程。其中step3也是比較重要的方法，進入該方法:
<code-box id="8HWMzh" style="padding: 0px; margin: 10px 0px; color: rgb(34, 34, 34); font-family: -apple-system, "SF UI Text", Arial, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "WenQuanYi Micro Hei", sans-serif; font-size: 15.5px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgba(255, 255, 255, 0.9); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; position: relative; display: block;"><pre id="pre-8HWMzh" class="hljs livescript mCustomScrollbar _mCS_4 mCS-autoHide" style="padding: 10px !important; margin: 5px 15px; overflow: visible; display: block; background: rgb(43, 43, 43); color: rgb(248, 248, 242); touch-action: pinch-zoom; font-size: 14px !important; font-weight: 400; font-family: "Ubuntu Mono", monospace !important; white-space: pre; overflow-wrap: normal; border-radius: 5px !important; word-break: break-all; counter-reset: itemcounter 0; line-height: 1.5 !important; position: relative;">
<code-pre class="code-pre" id="pre-8EN74w" style="padding: 0px 0px 0px 10px; margin: 0px; position: relative; display: block; left: 30px; border-left: 1px solid rgb(153, 153, 153);">protected Object initializeBean(String beanName, Object bean, @Nullable RootBeanDefinition mbd) {
if (System.getSecurityManager() != null) {
AccessController.doPrivileged((PrivilegedAction<Object>) () -> { invokeAwareMethods(beanName, bean); return null; }, getAccessControlContext()); } else { // 激活aware接口 invokeAwareMethods(beanName, bean); } Object wrappedBean = bean; if (mbd == null || !mbd.isSynthetic()) { // 初始化前處理的beanPostProcessor wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName); } try { // 激活 init-method方法 invokeInitMethods(beanName, wrappedBean, mbd); } catch (Throwable ex) { throw new BeanCreationException( (mbd != null ? mbd.getResourceDescription() : null), beanName, "Invocation of init method failed", ex); } if (mbd == null || !mbd.isSynthetic()) { // 初始化後處理的beanPostProcessor wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName); } return wrappedBean; }</code-pre>
</pre></code-box>
從上面源碼可知，梳理出主要的四個步驟：
step1:激活aware接口，完成aware接口的相關操作；
step2:初始化前處理的beanPostProcessor；
step3:完成init-method方法；
step4:初始化後處理的beanPostProcessor;
BeanPostProcessor作用是對初始化後的bean進行增強處理，在該階段 BeanPostProcessor 會處理當前容器內所有符合條件的實例化後的 bean 對象。它主要是對 Spring 容器提供的 bean 實例對象進行有效的擴展，允許Spring在初始化 bean 階段對其進行定製化修改，如處理標記接口或者爲其提供代理實現。
4. 演示
定義一個MyBeanPostProcessor實現BeanPostProcessor接口
<code-box id="TNQzyj" style="padding: 0px; margin: 10px 0px; color: rgb(34, 34, 34); font-family: -apple-system, "SF UI Text", Arial, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "WenQuanYi Micro Hei", sans-serif; font-size: 15.5px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgba(255, 255, 255, 0.9); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; position: relative; display: block;"><pre id="pre-TNQzyj" class="hljs java mCustomScrollbar _mCS_5 mCS-autoHide" style="padding: 10px !important; margin: 5px 15px; overflow: visible; display: block; background: rgb(43, 43, 43); color: rgb(248, 248, 242); touch-action: pinch-zoom; font-size: 14px !important; font-weight: 400; font-family: "Ubuntu Mono", monospace !important; white-space: pre; overflow-wrap: normal; border-radius: 5px !important; word-break: break-all; counter-reset: itemcounter 0; line-height: 1.5 !important; position: relative;">
<code-pre class="code-pre" id="pre-CyN7jd" style="padding: 0px 0px 0px 10px; margin: 0px; position: relative; display: block; left: 30px; border-left: 1px solid rgb(153, 153, 153);">public class MyBeanPostProcessor implements BeanPostProcessor {
@Override
public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
System.out.println("post Process Before Initialization 被調用...");
return bean;
}
@Override
public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
System.out.println("post Process after Initialization 被調用...");
return bean;
}
}</code-pre>
</pre></code-box>
定義一個LifeCycleBean類，實現如下接口：
<code-box id="WiaQRB" style="padding: 0px; margin: 10px 0px; color: rgb(34, 34, 34); font-family: -apple-system, "SF UI Text", Arial, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "WenQuanYi Micro Hei", sans-serif; font-size: 15.5px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgba(255, 255, 255, 0.9); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; position: relative; display: block;"><pre id="pre-WiaQRB" class="hljs cs mCustomScrollbar _mCS_6 mCS-autoHide" style="padding: 10px !important; margin: 5px 15px; overflow: visible; display: block; background: rgb(43, 43, 43); color: rgb(248, 248, 242); touch-action: pinch-zoom; font-size: 14px !important; font-weight: 400; font-family: "Ubuntu Mono", monospace !important; white-space: pre; overflow-wrap: normal; border-radius: 5px !important; word-break: break-all; counter-reset: itemcounter 0; line-height: 1.5 !important; position: relative;">
<code-pre class="code-pre" id="pre-ZG6ZfE" style="padding: 0px 0px 0px 10px; margin: 0px; position: relative; display: block; left: 30px; border-left: 1px solid rgb(153, 153, 153);">public class LifeCycleBean implements BeanNameAware, BeanFactoryAware, BeanClassLoaderAware,
InitializingBean, DisposableBean {
private String property;
public String getProperty() {
return property;
}
public void setProperty(String property) {
System.out.println("屬性注入....");
this.property = property;
}
public LifeCycleBean(){
System.out.println("構造函數調用...");
}
@Override public void setBeanClassLoader(ClassLoader classLoader) {
System.out.println("BeanClassLoaderAware 被調用...");
}
@Override public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
System.out.println("BeanFactoryAware 被調用...");
}
@Override public void setBeanName(String name) {
System.out.println("BeanNameAware 被調用...");
}
@Override public void destroy() throws Exception {
System.out.println("DisposableBean destroy 被調用...");
}
@Override public void afterPropertiesSet() throws Exception {
System.out.println("InitializingBean afterPropertiesSet 被調用...");
}
public void initMethod(){
System.out.println("init-method 被調用...");
}
public void destroyMethod(){
System.out.println("destroy-method 被調用...");
}
public void display(){
System.out.println("方法調用...");
}
}</code-pre>
</pre></code-box>
指定配置文件spring.xml，配置init-method與destroy-method方法
<code-box id="n3hbaF" style="padding: 0px; margin: 10px 0px; color: rgb(34, 34, 34); font-family: -apple-system, "SF UI Text", Arial, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "WenQuanYi Micro Hei", sans-serif; font-size: 15.5px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgba(255, 255, 255, 0.9); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; position: relative; display: block;"><pre id="pre-n3hbaF" class="hljs javascript mCustomScrollbar _mCS_7 mCS-autoHide" style="padding: 10px !important; margin: 5px 15px; overflow: visible; display: block; background: rgb(43, 43, 43); color: rgb(248, 248, 242); touch-action: pinch-zoom; font-size: 14px !important; font-weight: 400; font-family: "Ubuntu Mono", monospace !important; white-space: pre; overflow-wrap: normal; border-radius: 5px !important; word-break: break-all; counter-reset: itemcounter 0; line-height: 1.5 !important; position: relative;">
<code-pre class="code-pre" id="pre-xNSXpG" style="padding: 0px 0px 0px 10px; margin: 0px; position: relative; display: block; left: 30px; border-left: 1px solid rgb(153, 153, 153);"><bean id="lifeCycle" class="com.wzj.bean.LifeCycleBean"
init-method="initMethod" destroy-method="destroyMethod">
<property name="property" value="property"/> </bean>
<bean id="myBeanPostProcessor" class="com.wzj.bean.MyBeanPostProcessor" >
</bean></code-pre>
</pre></code-box>
測試類如下：
<code-box id="dzMaNy" style="padding: 0px; margin: 10px 0px; color: rgb(34, 34, 34); font-family: -apple-system, "SF UI Text", Arial, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "WenQuanYi Micro Hei", sans-serif; font-size: 15.5px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgba(255, 255, 255, 0.9); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; position: relative; display: block;"><pre id="pre-dzMaNy" class="hljs groovy mCustomScrollbar _mCS_8 mCS-autoHide" style="padding: 10px !important; margin: 5px 15px; overflow: visible; display: block; background: rgb(43, 43, 43); color: rgb(248, 248, 242); touch-action: pinch-zoom; font-size: 14px !important; font-weight: 400; font-family: "Ubuntu Mono", monospace !important; white-space: pre; overflow-wrap: normal; border-radius: 5px !important; word-break: break-all; counter-reset: itemcounter 0; line-height: 1.5 !important; position: relative;">
<code-pre class="code-pre" id="pre-4hnwjM" style="padding: 0px 0px 0px 10px; margin: 0px; position: relative; display: block; left: 30px; border-left: 1px solid rgb(153, 153, 153);">@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = {"classpath:spring.xml"})
public class TestSpring {
@Test
public void testLifeCycleBean() {
ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("spring.xml");
}</code-pre>
</pre></code-box>
執行結果：
<code-box id="mndr4h" style="padding: 0px; margin: 10px 0px; color: rgb(34, 34, 34); font-family: -apple-system, "SF UI Text", Arial, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "WenQuanYi Micro Hei", sans-serif; font-size: 15.5px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: left; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgba(255, 255, 255, 0.9); text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial; position: relative; display: block;"><pre id="pre-mndr4h" class="hljs erlang mCustomScrollbar _mCS_9 mCS-autoHide" style="padding: 10px !important; margin: 5px 15px; overflow: visible; display: block; background: rgb(43, 43, 43); color: rgb(248, 248, 242); touch-action: pinch-zoom; font-size: 14px !important; font-weight: 400; font-family: "Ubuntu Mono", monospace !important; white-space: pre; overflow-wrap: normal; border-radius: 5px !important; word-break: break-all; counter-reset: itemcounter 0; line-height: 1.5 !important; position: relative;">
<code-pre class="code-pre" id="pre-e4R3km" style="padding: 0px 0px 0px 10px; margin: 0px; position: relative; display: block; left: 30px; border-left: 1px solid rgb(153, 153, 153);">構造函數調用...
屬性注入....
BeanNameAware 被調用...
BeanClassLoaderAware 被調用...
BeanFactoryAware 被調用...
post Process Before Initialization 被調用...
InitializingBean afterPropertiesSet 被調用...
init-method 被調用...
post Process after Initialization 被調用...
DisposableBean destroy 被調用...
destroy-method 被調用...</code-pre>
</pre></code-box>
4. 總結
本篇從一個初學者的角度概覽了bean的整個生命週期，並描述了其中的主要流程，閱讀源碼的初始階段，優先抓住主要流程，別陷入細節，並通過跑案例、寫註解、畫流程圖等方式加深理解，後續將繼續分析bean實例化中的核心流程、設計思想等。