Java教程
Spring DI源码分析5
本文主要是介绍Spring DI源码分析5，对大家解决编程问题具有一定的参考价值，需要的程序猿们随着小编来一起学习吧！
本篇主要是创建Bean后的属性注入
给bean设置属性
protected void populateBean(String beanName, RootBeanDefinition mbd, @Nullable BeanWrapper bw) {
if (bw == null) {
if (mbd.hasPropertyValues()) {
throw new BeanCreationException(
mbd.getResourceDescription(), beanName, "Cannot apply property values to null instance");
}
else {
// Skip property population phase for null instance.
return;
}
}
//属性注入
boolean continueWithPropertyPopulation = true;
if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {
for (BeanPostProcessor bp : getBeanPostProcessors()) {
if (bp instanceof InstantiationAwareBeanPostProcessor) {
InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
if (!ibp.postProcessAfterInstantiation(bw.getWrappedInstance(), beanName)) {
continueWithPropertyPopulation = false;
break;
}
}
}
}
if (!continueWithPropertyPopulation) {
return;
}
//获取要为bean设置的属性值
PropertyValues pvs = (mbd.hasPropertyValues() ? mbd.getPropertyValues() : null);
//对依赖注入处理，处理autowiring自动装配的依赖注入 通过名称 或者 通过类型
if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_NAME ||
mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_TYPE) {
MutablePropertyValues newPvs = new MutablePropertyValues(pvs);
//根据Bean名称进行autowiring自动装配处理
if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_NAME) {
autowireByName(beanName, mbd, bw, newPvs);
}
//根据Bean类型进行autowiring自动装配处理
if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_TYPE) {
autowireByType(beanName, mbd, bw, newPvs);
}
pvs = newPvs;
}
//对非autowiring的属性进行依赖注入处理
boolean hasInstAwareBpps = hasInstantiationAwareBeanPostProcessors();
boolean needsDepCheck = (mbd.getDependencyCheck() != RootBeanDefinition.DEPENDENCY_CHECK_NONE);
if (hasInstAwareBpps || needsDepCheck) {
if (pvs == null) {
pvs = mbd.getPropertyValues();
}
PropertyDescriptor[] filteredPds = filterPropertyDescriptorsForDependencyCheck(bw, mbd.allowCaching);
if (hasInstAwareBpps) {
for (BeanPostProcessor bp : getBeanPostProcessors()) {
if (bp instanceof InstantiationAwareBeanPostProcessor) {
InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
pvs = ibp.postProcessPropertyValues(pvs, filteredPds, bw.getWrappedInstance(), beanName);
if (pvs == null) {
return;
}
}
}
}
if (needsDepCheck) {
checkDependencies(beanName, mbd, filteredPds, pvs);
}
}
if (pvs != null) {
//对属性进行注入，和上面的自动注入不冲突，上面的判断会将两个操作互斥
applyPropertyValues(beanName, mbd, bw, pvs);
}
}
通过名字依赖注入
protected void autowireByName(
String beanName, AbstractBeanDefinition mbd, BeanWrapper bw, MutablePropertyValues pvs) {
//获取非简单类型的属性，
String[] propertyNames = unsatisfiedNonSimpleProperties(mbd, bw);
for (String propertyName : propertyNames) {
//如果Spring IOC容器中包含指定名称的Bean
if (containsBean(propertyName)) {
//调用getBean方法向IOC容器索取指定名称的Bean实例，进行属性的初始化和依赖注入
Object bean = getBean(propertyName);
//为指定名称的属性赋予属性值
pvs.add(propertyName, bean);
//指定名称属性注册依赖Bean名称，进行属性依赖注入
registerDependentBean(propertyName, beanName);
if (logger.isDebugEnabled()) {
logger.debug("Added autowiring by name from bean name '" + beanName +
"' via property '" + propertyName + "' to bean named '" + propertyName + "'");
}
}
else {
if (logger.isTraceEnabled()) {
logger.trace("Not autowiring property '" + propertyName + "' of bean '" + beanName +
"' by name: no matching bean found");
}
}
}
}
获得所有的非简单属性
protected String[] unsatisfiedNonSimpleProperties(AbstractBeanDefinition mbd, BeanWrapper bw) {
Set<String> result = new TreeSet<>();
PropertyValues pvs = mbd.getPropertyValues();
PropertyDescriptor[] pds = bw.getPropertyDescriptors();
for (PropertyDescriptor pd : pds) {
if (pd.getWriteMethod() != null && !isExcludedFromDependencyCheck(pd) && !pvs.contains(pd.getName()) &&
!BeanUtils.isSimpleProperty(pd.getPropertyType())) {
result.add(pd.getName());
}
}
return StringUtils.toStringArray(result);
}
简单属性
public static boolean isSimpleProperty(Class<?> clazz) {
Assert.notNull(clazz, "Class must not be null");
return isSimpleValueType(clazz) || (clazz.isArray() && isSimpleValueType(clazz.getComponentType()));
}
//简单属性
public static boolean isSimpleValueType(Class<?> clazz) {
return (ClassUtils.isPrimitiveOrWrapper(clazz) || clazz.isEnum() ||
CharSequence.class.isAssignableFrom(clazz) ||
Number.class.isAssignableFrom(clazz) ||
Date.class.isAssignableFrom(clazz) ||
URI.class == clazz || URL.class == clazz ||
Locale.class == clazz || Class.class == clazz);
}
通过类型依赖注入
protected void autowireByType(
String beanName, AbstractBeanDefinition mbd, BeanWrapper bw, MutablePropertyValues pvs) {
//获取用户定义的类型转换器
TypeConverter converter = getCustomTypeConverter();
if (converter == null) {
converter = bw;
}
//存放解析的要注入的属性
Set<String> autowiredBeanNames = new LinkedHashSet<>(4);
String[] propertyNames = unsatisfiedNonSimpleProperties(mbd, bw);
for (String propertyName : propertyNames) {
try {
//获取属性名称的属性描述器
PropertyDescriptor pd = bw.getPropertyDescriptor(propertyName);
//不对Object类型的属性进行autowiring自动依赖注入
if (Object.class != pd.getPropertyType()) {
//获取属性的写方法(setter方法)
MethodParameter methodParam = BeanUtils.getWriteMethodParameter(pd);
//优先处理postProcessor，不允许bean初始化
boolean eager = !PriorityOrdered.class.isInstance(bw.getWrappedInstance());
//创建一个要被注入的依赖描述
DependencyDescriptor desc = new AutowireByTypeDependencyDescriptor(methodParam, eager);
//解析依赖，返回所有要被注入的Bean对象
Object autowiredArgument = resolveDependency(desc, beanName, autowiredBeanNames, converter);
if (autowiredArgument != null) {
//为属性赋值所引用的对象
pvs.add(propertyName, autowiredArgument);
}
for (String autowiredBeanName : autowiredBeanNames) {
//指定名称属性注册依赖Bean名称，进行属性依赖注入
registerDependentBean(autowiredBeanName, beanName);
if (logger.isDebugEnabled()) {
logger.debug("Autowiring by type from bean name '" + beanName + "' via property '" +
propertyName + "' to bean named '" + autowiredBeanName + "'");
}
}
//释放已自动注入的属性
autowiredBeanNames.clear();
}
}
catch (BeansException ex) {
throw new UnsatisfiedDependencyException(mbd.getResourceDescription(), beanName, propertyName, ex);
}
}
}
解析依赖
public Object resolveDependency(DependencyDescriptor descriptor, @Nullable String requestingBeanName,
@Nullable Set<String> autowiredBeanNames, @Nullable TypeConverter typeConverter) throws BeansException {
descriptor.initParameterNameDiscovery(getParameterNameDiscoverer());
if (Optional.class == descriptor.getDependencyType()) {
return createOptionalDependency(descriptor, requestingBeanName);
}
else if (ObjectFactory.class == descriptor.getDependencyType() ||
ObjectProvider.class == descriptor.getDependencyType()) {
return new DependencyObjectProvider(descriptor, requestingBeanName);
}
else if (javaxInjectProviderClass == descriptor.getDependencyType()) {
return new Jsr330ProviderFactory().createDependencyProvider(descriptor, requestingBeanName);
}
else {
Object result = getAutowireCandidateResolver().getLazyResolutionProxyIfNecessary(
descriptor, requestingBeanName);
if (result == null) {
result = doResolveDependency(descriptor, requestingBeanName, autowiredBeanNames, typeConverter);
}
return result;
}
}
设置属性
protected void applyPropertyValues(String beanName, BeanDefinition mbd, BeanWrapper bw, PropertyValues pvs) {
if (pvs.isEmpty()) {
return;
}
//封装属性值
MutablePropertyValues mpvs = null;
List<PropertyValue> original;
if (System.getSecurityManager() != null) {
if (bw instanceof BeanWrapperImpl) {
//设置安全上下文，JDK安全机制
((BeanWrapperImpl) bw).setSecurityContext(getAccessControlContext());
}
}
if (pvs instanceof MutablePropertyValues) {
mpvs = (MutablePropertyValues) pvs;
//属性值已经转换
if (mpvs.isConverted()) {
try {
//为实例化对象设置属性值
bw.setPropertyValues(mpvs);
return;
}
catch (BeansException ex) {
throw new BeanCreationException(
mbd.getResourceDescription(), beanName, "Error setting property values", ex);
}
}
//获取属性值对象的原始类型值
original = mpvs.getPropertyValueList();
}
else {
original = Arrays.asList(pvs.getPropertyValues());
}
//获取用户自定义的类型转换
TypeConverter converter = getCustomTypeConverter();
if (converter == null) {
converter = bw;
}
//创建一个Bean定义属性值解析器，将Bean定义中的属性值解析为Bean实例对象的实际值
BeanDefinitionValueResolver valueResolver = new BeanDefinitionValueResolver(this, beanName, mbd, converter);
//为属性的解析值创建一个深拷贝，将拷贝的数据注入到实例对象中
List<PropertyValue> deepCopy = new ArrayList<>(original.size());
boolean resolveNecessary = false;
for (PropertyValue pv : original) {
//属性值不需要转换
if (pv.isConverted()) {
deepCopy.add(pv);
}
//属性值需要转换
else {
String propertyName = pv.getName();
//原始的属性值，即转换之前的属性值
Object originalValue = pv.getValue();
//转换属性值
Object resolvedValue = valueResolver.resolveValueIfNecessary(pv, originalValue);
//转换之后的属性值
Object convertedValue = resolvedValue;
//属性值是否可以转换
boolean convertible = bw.isWritableProperty(propertyName) &&
!PropertyAccessorUtils.isNestedOrIndexedProperty(propertyName);
if (convertible) {
//使用用户自定义的类型转换器转换属性值
convertedValue = convertForProperty(resolvedValue, propertyName, bw, converter);
}
//存储转换后的属性值，避免每次属性注入时的转换工作
if (resolvedValue == originalValue) {
if (convertible) {
//设置属性转换之后的值
pv.setConvertedValue(convertedValue);
}
deepCopy.add(pv);
}
//属性是可转换的，且属性原始值是字符串类型，且属性的原始类型值不是
//动态生成的字符串，且属性的原始值不是集合或者数组类型
else if (convertible && originalValue instanceof TypedStringValue &&
!((TypedStringValue) originalValue).isDynamic() &&
!(convertedValue instanceof Collection || ObjectUtils.isArray(convertedValue))) {
pv.setConvertedValue(convertedValue);
//重新封装属性的值
deepCopy.add(pv);
}
else {
resolveNecessary = true;
deepCopy.add(new PropertyValue(pv, convertedValue));
}
}
}
if (mpvs != null && !resolveNecessary) {
//标记属性值已经转换过
mpvs.setConverted();
}
//进行属性依赖注入
try {
bw.setPropertyValues(new MutablePropertyValues(deepCopy));
}
catch (BeansException ex) {
throw new BeanCreationException(
mbd.getResourceDescription(), beanName, "Error setting property values", ex);
}
}
调用bean的初始化方法，定义的initmethod
protected Object initializeBean(final String beanName, final Object bean, @Nullable RootBeanDefinition mbd) {
//JDK的安全机制验证权限
if (System.getSecurityManager() != null) {
//实现PrivilegedAction接口的匿名内部类
AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
invokeAwareMethods(beanName, bean);
return null;
}, getAccessControlContext());
}
else {
//为Bean实例对象包装相关属性，如名称，类加载器，所属容器等信息
invokeAwareMethods(beanName, bean);
}
Object wrappedBean = bean;
//bean后置处理器，bean初始化前的处理
if (mbd == null || !mbd.isSynthetic()) {
wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);
}
//调用Bean实例对象初始化的方法，类中的initMethod
try {
invokeInitMethods(beanName, wrappedBean, mbd);
}
catch (Throwable ex) {
throw new BeanCreationException(
(mbd != null ? mbd.getResourceDescription() : null),
beanName, "Invocation of init method failed", ex);
}
//bean后置处理器，bean初始化后的操作
if (mbd == null || !mbd.isSynthetic()) {
wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);
}
return wrappedBean;
}
//填充包装属性
private void invokeAwareMethods(final String beanName, final Object bean) {
if (bean instanceof Aware) {
if (bean instanceof BeanNameAware) {
((BeanNameAware) bean).setBeanName(beanName);
}
if (bean instanceof BeanClassLoaderAware) {
ClassLoader bcl = getBeanClassLoader();
if (bcl != null) {
((BeanClassLoaderAware) bean).setBeanClassLoader(bcl);
}
}
if (bean instanceof BeanFactoryAware) {
((BeanFactoryAware) bean).setBeanFactory(AbstractAutowireCapableBeanFactory.this);
}
}
}
//调用initmethod初始化方法
protected void invokeInitMethods(String beanName, final Object bean, @Nullable RootBeanDefinition mbd)
throws Throwable {
boolean isInitializingBean = (bean instanceof InitializingBean);
if (isInitializingBean && (mbd == null || !mbd.isExternallyManagedInitMethod("afterPropertiesSet"))) {
if (logger.isDebugEnabled()) {
logger.debug("Invoking afterPropertiesSet() on bean with name '" + beanName + "'");
}
if (System.getSecurityManager() != null) {
try {
AccessController.doPrivileged((PrivilegedExceptionAction<Object>) () -> {
((InitializingBean) bean).afterPropertiesSet();
return null;
}, getAccessControlContext());
}
catch (PrivilegedActionException pae) {
throw pae.getException();
}
}
else {
((InitializingBean) bean).afterPropertiesSet();
}
}
if (mbd != null && bean.getClass() != NullBean.class) {
String initMethodName = mbd.getInitMethodName();
if (StringUtils.hasLength(initMethodName) &&
!(isInitializingBean && "afterPropertiesSet".equals(initMethodName)) &&
!mbd.isExternallyManagedInitMethod(initMethodName)) {
invokeCustomInitMethod(beanName, bean, mbd);
}
}
}
//调用自定义的initmethod
protected void invokeCustomInitMethod(String beanName, final Object bean, RootBeanDefinition mbd)
throws Throwable {
String initMethodName = mbd.getInitMethodName();
Assert.state(initMethodName != null, "No init method set");
final Method initMethod = (mbd.isNonPublicAccessAllowed() ?
BeanUtils.findMethod(bean.getClass(), initMethodName) :
ClassUtils.getMethodIfAvailable(bean.getClass(), initMethodName));
if (initMethod == null) {
if (mbd.isEnforceInitMethod()) {
throw new BeanDefinitionValidationException("Couldn't find an init method named '" +
initMethodName + "' on bean with name '" + beanName + "'");
}
else {
if (logger.isDebugEnabled()) {
logger.debug("No default init method named '" + initMethodName +
"' found on bean with name '" + beanName + "'");
}
// Ignore non-existent default lifecycle methods.
return;
}
}
if (logger.isDebugEnabled()) {
logger.debug("Invoking init method '" + initMethodName + "' on bean with name '" + beanName + "'");
}
if (System.getSecurityManager() != null) {
AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
ReflectionUtils.makeAccessible(initMethod);
return null;
});
try {
AccessController.doPrivileged((PrivilegedExceptionAction<Object>) () ->
initMethod.invoke(bean), getAccessControlContext());
}
catch (PrivilegedActionException pae) {
InvocationTargetException ex = (InvocationTargetException) pae.getException();
throw ex.getTargetException();
}
}
else {
try {
//反射调用initmethod
ReflectionUtils.makeAccessible(initMethod);
initMethod.invoke(bean);
}
catch (InvocationTargetException ex) {
throw ex.getTargetException();
}
}
}
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