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锁定老帖子 主题：Spring源码浅析 -- 依赖注入
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发表时间：2010-08-21
Ioc已经完成了对配置文件的载入和解析，接下来将会完成Ioc容器的核心功能 依赖注入。 在依赖注入之前，还要进行对bean的生成和初始化，生成方式分为两种JDK自身的方式和引入CGLIB类库的方式。 首先就从触发这一系列过程的入口说起，BeanFactroy.getBean
1.bean在BeanFactroy中的生成 getBean方法的具体实现是在AbstractBeanFactory中 public Object getBean(String name) throws BeansException {
return doGetBean(name, null, null, false);
}
它会调用doGetBean方法 @SuppressWarnings("unchecked")
private <T> T doGetBean(
final String name, final Class<T> requiredType, final Object[] args, boolean typeCheckOnly)
throws BeansException {
final String beanName = transformedBeanName(name);
Object bean;
// Eagerly check singleton cache for manually registered singletons.
Object sharedInstance = getSingleton(beanName);
if (sharedInstance != null && args == null) {
if (logger.isDebugEnabled()) {
if (isSingletonCurrentlyInCreation(beanName)) {
logger.debug("Returning eagerly cached instance of singleton bean '" + beanName +
"' that is not fully initialized yet - a consequence of a circular reference");
}
else {
logger.debug("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 (args != null) {
// Delegation to parent with explicit args.
return (T) parentBeanFactory.getBean(nameToLookup, args);
}
else {
// No args -> delegate to standard getBean method.
return parentBeanFactory.getBean(nameToLookup, requiredType);
}
}
if (!typeCheckOnly) {
markBeanAsCreated(beanName);
}
final 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 dependsOnBean : dependsOn) {
getBean(dependsOnBean);
registerDependentBean(dependsOnBean, beanName);
}
}
// Create bean instance.
if (mbd.isSingleton()) {
sharedInstance = getSingleton(beanName, new ObjectFactory() {
public Object getObject() throws BeansException {
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);
}
else if (mbd.isPrototype()) {
// It's a prototype -> create a new instance.
Object prototypeInstance = null;
try {
beforePrototypeCreation(beanName);
prototypeInstance = createBean(beanName, mbd, args);
}
finally {
afterPrototypeCreation(beanName);
}
bean = getObjectForBeanInstance(prototypeInstance, name, beanName, mbd);
}
else {
String scopeName = mbd.getScope();
final Scope scope = this.scopes.get(scopeName);
if (scope == null) {
throw new IllegalStateException("No Scope registered for scope '" + scopeName + "'");
}
try {
Object scopedInstance = scope.get(beanName, new ObjectFactory() {
public Object getObject() throws BeansException {
beforePrototypeCreation(beanName);
try {
return createBean(beanName, mbd, args);
}
finally {
afterPrototypeCreation(beanName);
}
}
});
bean = getObjectForBeanInstance(scopedInstance, name, beanName, mbd);
}
catch (IllegalStateException ex) {
throw new BeanCreationException(beanName,
"Scope '" + scopeName + "' is not active for the current thread; " +
"consider defining a scoped proxy for this bean if you intend to refer to it from a singleton",
ex);
}
}
}
// Check if required type matches the type of the actual bean instance.
if (requiredType != null && bean != null && !requiredType.isAssignableFrom(bean.getClass())) {
throw new BeanNotOfRequiredTypeException(name, requiredType, bean.getClass());
}
return (T) bean;
}
这个方法首先处理beanName（transformedBeanName(name)），因为会用&开头的情况，然后会在以前的singleton缓存中去找需要的bean（getSingleton(beanName)），因为如果是singleton的bean就不用再创建，然后判断此bean是否在此beanfactory中定义（containsBeanDefinition(beanName)），如果没有递归至双亲beanfactory，以上条件不满足的话，接下来得到beandefination的定义（getMergedLocalBeanDefinition(beanName)），开始创建bean，第一步分析此bean的depand-on的情况，先把它们初始化，第二步判断bean的生命周期，如果是singleton的话，使用对应的singletonFactory来生成，如果是prototype的，使用createBean(beanName, mbd, args)方法生成。
createBean(beanName, mbd, args)方法的具体实现是在AbstractAutowireCapableBeanFactory中实现
@Override
protected Object createBean(final String beanName, final RootBeanDefinition mbd, final Object[] args)
throws BeanCreationException {
if (logger.isDebugEnabled()) {
logger.debug("Creating instance of bean '" + beanName + "'");
}
// Make sure bean class is actually resolved at this point.
resolveBeanClass(mbd, beanName);
// Prepare method overrides.
try {
mbd.prepareMethodOverrides();
}
catch (BeanDefinitionValidationException ex) {
throw new BeanDefinitionStoreException(mbd.getResourceDescription(),
beanName, "Validation of method overrides failed", ex);
}
try {
// Give BeanPostProcessors a chance to return a proxy instead of the target bean instance.
Object bean = resolveBeforeInstantiation(beanName, mbd);
if (bean != null) {
return bean;
}
}
catch (Throwable ex) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName,
"BeanPostProcessor before instantiation of bean failed", ex);
}
Object beanInstance = doCreateBean(beanName, mbd, args);
if (logger.isDebugEnabled()) {
logger.debug("Finished creating instance of bean '" + beanName + "'");
}
return beanInstance;
}
除去一些验证工作，创建bean在doCreateBean(beanName, mbd, args)中实现
protected Object doCreateBean(final String beanName, final RootBeanDefinition mbd, final Object[] args) {
// Instantiate the bean.
BeanWrapper instanceWrapper = null;
if (mbd.isSingleton()) {
instanceWrapper = this.factoryBeanInstanceCache.remove(beanName);
}
if (instanceWrapper == null) {
instanceWrapper = createBeanInstance(beanName, mbd, args);
}
final Object bean = (instanceWrapper != null ? instanceWrapper.getWrappedInstance() : null);
Class beanType = (instanceWrapper != null ? instanceWrapper.getWrappedClass() : null);
// Allow post-processors to modify the merged bean definition.
synchronized (mbd.postProcessingLock) {
if (!mbd.postProcessed) {
applyMergedBeanDefinitionPostProcessors(mbd, beanType, beanName);
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.isDebugEnabled()) {
logger.debug("Eagerly caching bean '" + beanName +
"' to allow for resolving potential circular references");
}
addSingletonFactory(beanName, new ObjectFactory() {
public Object getObject() throws BeansException {
return getEarlyBeanReference(beanName, mbd, bean);
}
});
}
// Initialize the bean instance.
Object exposedObject = bean;
try {
populateBean(beanName, mbd, instanceWrapper);
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<String>(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 " +
"'getBeanNamesOfType' with the 'allowEagerInit' flag turned off, for example.");
}
}
}
}
// Register bean as disposable.
try {
registerDisposableBeanIfNecessary(beanName, bean, mbd);
}
catch (BeanDefinitionValidationException ex) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName, "Invalid destruction signature", ex);
}
return exposedObject;
}
在此引入一个bean的包装类BeanWrapper，如果是singleton的，先从缓存中取（instanceWrapper = this.factoryBeanInstanceCache.remove(beanName)），如果为null的话 进入createBeanInstance(beanName, mbd, args)方法
protected BeanWrapper createBeanInstance(String beanName, RootBeanDefinition mbd, Object[] args) {
// Make sure bean class is actually resolved at this point.
Class beanClass = resolveBeanClass(mbd, beanName);
if (beanClass != null && !Modifier.isPublic(beanClass.getModifiers()) && !mbd.isNonPublicAccessAllowed()) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName,
"Bean class isn't public, and non-public access not allowed: " + beanClass.getName());
}
if (mbd.getFactoryMethodName() != null) {
return instantiateUsingFactoryMethod(beanName, mbd, args);
}
// Shortcut when re-creating the same bean...
if (mbd.resolvedConstructorOrFactoryMethod != null && args == null) {
if (mbd.constructorArgumentsResolved) {
return autowireConstructor(beanName, mbd, null, null);
}
else {
return instantiateBean(beanName, mbd);
}
}
// Need to determine the constructor...
Constructor[] ctors = determineConstructorsFromBeanPostProcessors(beanClass, beanName);
if (ctors != null ||
mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_CONSTRUCTOR ||
mbd.hasConstructorArgumentValues() || !ObjectUtils.isEmpty(args)) {
return autowireConstructor(beanName, mbd, ctors, args);
}
// No special handling: simply use no-arg constructor.
return instantiateBean(beanName, mbd);
}
如果此bean配置了工厂方法（mbd.getFactoryMethodName() != null），则使用工厂类进行bean的创建，如果此bean注入了构造器参数（ctors != null），则使用非默认的构造器对应的方法autowireConstructor进行生成，最后一种情况是最常见的，非工厂类，且使用默认无参的构造方法，instantiateBean(beanName, mbd)
protected BeanWrapper instantiateBean(final String beanName, final RootBeanDefinition mbd) {
try {
Object beanInstance;
final BeanFactory parent = this;
if (System.getSecurityManager() != null) {
beanInstance = AccessController.doPrivileged(new PrivilegedAction<Object>() {
public Object run() {
return getInstantiationStrategy().instantiate(mbd, beanName, parent);
}
}, getAccessControlContext());
}
else {
beanInstance = getInstantiationStrategy().instantiate(mbd, beanName, parent);
}
BeanWrapper bw = new BeanWrapperImpl(beanInstance);
initBeanWrapper(bw);
return bw;
}
catch (Throwable ex) {
throw new BeanCreationException(mbd.getResourceDescription(), beanName, "Instantiation of bean failed", ex);
}
}
在这里首先生成beanInstance对象，然后在对它进行包装（BeanWrapper bw = new BeanWrapperImpl(beanInstance)） 继而完成bean的生成，生成beanInstance 使用getInstantiationStrategy().instantiate(mbd, beanName, parent)方法，在此首先得到InstantiationStrategy的对象，然后进行instantiate，具体实现是在SimpleInstantiationStrategy类中，
public Object instantiate(
RootBeanDefinition beanDefinition, String beanName, BeanFactory owner) {
// Don't override the class with CGLIB if no overrides.
if (beanDefinition.getMethodOverrides().isEmpty()) {
Constructor constructorToUse = (Constructor) beanDefinition.resolvedConstructorOrFactoryMethod;
if (constructorToUse == null) {
final Class clazz = beanDefinition.getBeanClass();
if (clazz.isInterface()) {
throw new BeanInstantiationException(clazz, "Specified class is an interface");
}
try {
if (System.getSecurityManager() != null) {
constructorToUse = AccessController.doPrivileged(new PrivilegedExceptionAction<Constructor>() {
public Constructor run() throws Exception {
return clazz.getDeclaredConstructor((Class[]) null);
}
});
} else {
constructorToUse = clazz.getDeclaredConstructor((Class[]) null);
}
beanDefinition.resolvedConstructorOrFactoryMethod = constructorToUse;
}
catch (Exception ex) {
throw new BeanInstantiationException(clazz, "No default constructor found", ex);
}
}
return BeanUtils.instantiateClass(constructorToUse);
}
else {
// Must generate CGLIB subclass.
return instantiateWithMethodInjection(beanDefinition, beanName, owner);
}
}
这里首先判断次beandefinetion的override方法是否为空，如果是则使用JDK反射进行生成，否则使用CGLIB进行生成。（这里的判断依据我不太明了，希望大牛们指出..）
2.依赖注入 完成了bean对象的生成，接下来就应该是核心的依赖注入了 再次回到AbstractAutowireCapableBeanFactory的doCreateBean方法中，依赖注入发生在populateBean(beanName, mbd, instanceWrapper)方法中
protected void populateBean(String beanName, AbstractBeanDefinition mbd, BeanWrapper bw) {
PropertyValues pvs = mbd.getPropertyValues();
if (bw == null) {
if (!pvs.isEmpty()) {
throw new BeanCreationException(
mbd.getResourceDescription(), beanName, "Cannot apply property values to null instance");
}
else {
// Skip property population phase for null instance.
return;
}
}
// Give any InstantiationAwareBeanPostProcessors the opportunity to modify the
// state of the bean before properties are set. This can be used, for example,
// to support styles of field injection.
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;
}
if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_NAME ||
mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_TYPE) {
MutablePropertyValues newPvs = new MutablePropertyValues(pvs);
// Add property values based on autowire by name if applicable.
if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_NAME) {
autowireByName(beanName, mbd, bw, newPvs);
}
// Add property values based on autowire by type if applicable.
if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_TYPE) {
autowireByType(beanName, mbd, bw, newPvs);
}
pvs = newPvs;
}
boolean hasInstAwareBpps = hasInstantiationAwareBeanPostProcessors();
boolean needsDepCheck = (mbd.getDependencyCheck() != RootBeanDefinition.DEPENDENCY_CHECK_NONE);
if (hasInstAwareBpps || needsDepCheck) {
PropertyDescriptor[] filteredPds = filterPropertyDescriptorsForDependencyCheck(bw);
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);
}
}
applyPropertyValues(beanName, mbd, bw, pvs);
}
首先判断是否有BeanPostProcessors（hasInstantiationAwareBeanPostProcessors()）如果有，则进行一些修改处理。然后判断是否有自动装配属性（mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_NAME || 如果有则进行自动装配。最后应用依赖注入applyPropertyValues(beanName, mbd, bw, pvs);
protected void applyPropertyValues(String beanName, BeanDefinition mbd, BeanWrapper bw, PropertyValues pvs) {
if (pvs == null || pvs.isEmpty()) {
return;
}
MutablePropertyValues mpvs = null;
List<PropertyValue> original;
if (System.getSecurityManager()!= null) {
if (bw instanceof BeanWrapperImpl) {
((BeanWrapperImpl) bw).setSecurityContext(getAccessControlContext());
}
}
if (pvs instanceof MutablePropertyValues) {
mpvs = (MutablePropertyValues) pvs;
if (mpvs.isConverted()) {
// Shortcut: use the pre-converted values as-is.
try {
bw.setPropertyValues(mpvs);
return;
}
catch (BeansException ex) {
throw new BeanCreationException(
mbd.getResourceDescription(), beanName, "Error setting property values", ex);
}
}
original = mpvs.getPropertyValueList();
}
else {
original = Arrays.asList(pvs.getPropertyValues());
}
TypeConverter converter = getCustomTypeConverter();
if (converter == null) {
converter = bw;
}
BeanDefinitionValueResolver valueResolver = new BeanDefinitionValueResolver(this, beanName, mbd, converter);
// Create a deep copy, resolving any references for values.
List<PropertyValue> deepCopy = new ArrayList<PropertyValue>(original.size());
boolean resolveNecessary = false;
for (PropertyValue pv : original) {
if (pv.isConverted()) {
deepCopy.add(pv);
}
else {
String propertyName = pv.getName();
Object originalValue = pv.getValue();
Object resolvedValue = valueResolver.resolveValueIfNecessary(pv, originalValue);
Object convertedValue = resolvedValue;
boolean convertible = bw.isWritableProperty(propertyName) &&
!PropertyAccessorUtils.isNestedOrIndexedProperty(propertyName);
if (convertible) {
convertedValue = convertForProperty(resolvedValue, propertyName, bw, converter);
}
// Possibly store converted value in merged bean definition,
// in order to avoid re-conversion for every created bean instance.
if (resolvedValue == originalValue) {
if (convertible) {
pv.setConvertedValue(convertedValue);
}
deepCopy.add(pv);
}
else if (convertible && originalValue instanceof TypedStringValue &&
!((TypedStringValue) originalValue).isDynamic() &&
!(convertedValue instanceof Collection || ObjectUtils.isArray(convertedValue))) {
pv.setConvertedValue(convertedValue);
deepCopy.add(pv);
}
else {
resolveNecessary = true;
deepCopy.add(new PropertyValue(pv, convertedValue));
}
}
}
if (mpvs != null && !resolveNecessary) {
mpvs.setConverted();
}
// Set our (possibly massaged) deep copy.
try {
bw.setPropertyValues(new MutablePropertyValues(deepCopy));
}
catch (BeansException ex) {
throw new BeanCreationException(
mbd.getResourceDescription(), beanName, "Error setting property values", ex);
}
}
这里首先对所有的属性值进行一次深拷贝（deepCopy.add(pv)），将拷贝的值注入bean 最后进行依赖注入，在BeanWrapper中完成 bw.setPropertyValues(new MutablePropertyValues(deepCopy)) 具体实现是在BeanWrapper中
@Override
public void setPropertyValue(PropertyValue pv) throws BeansException {
PropertyTokenHolder tokens = (PropertyTokenHolder) pv.resolvedTokens;
if (tokens == null) {
String propertyName = pv.getName();
BeanWrapperImpl nestedBw;
try {
nestedBw = getBeanWrapperForPropertyPath(propertyName);
}
catch (NotReadablePropertyException ex) {
throw new NotWritablePropertyException(getRootClass(), this.nestedPath + propertyName,
"Nested property in path '" + propertyName + "' does not exist", ex);
}
tokens = getPropertyNameTokens(getFinalPath(nestedBw, propertyName));
if (nestedBw == this) {
pv.getOriginalPropertyValue().resolvedTokens = tokens;
}
nestedBw.setPropertyValue(tokens, pv);
}
else {
setPropertyValue(tokens, pv);
}
}
这里面主要是生成一个PropertyTokenHolder对象 然后重载到setPropertyValue(tokens, pv)中 @SuppressWarnings("unchecked")
private void setPropertyValue(PropertyTokenHolder tokens, PropertyValue pv) throws BeansException {
String propertyName = tokens.canonicalName;
String actualName = tokens.actualName;
if (tokens.keys != null) {
// Apply indexes and map keys: fetch value for all keys but the last one.
PropertyTokenHolder getterTokens = new PropertyTokenHolder();
getterTokens.canonicalName = tokens.canonicalName;
getterTokens.actualName = tokens.actualName;
getterTokens.keys = new String[tokens.keys.length - 1];
System.arraycopy(tokens.keys, 0, getterTokens.keys, 0, tokens.keys.length - 1);
Object propValue;
try {
propValue = getPropertyValue(getterTokens);
}
catch (NotReadablePropertyException ex) {
throw new NotWritablePropertyException(getRootClass(), this.nestedPath + propertyName,
"Cannot access indexed value in property referenced " +
"in indexed property path '" + propertyName + "'", ex);
}
// Set value for last key.
String key = tokens.keys[tokens.keys.length - 1];
if (propValue == null) {
throw new NullValueInNestedPathException(getRootClass(), this.nestedPath + propertyName,
"Cannot access indexed value in property referenced " +
"in indexed property path '" + propertyName + "': returned null");
}
else if (propValue.getClass().isArray()) {
Class requiredType = propValue.getClass().getComponentType();
int arrayIndex = Integer.parseInt(key);
Object oldValue = null;
try {
if (isExtractOldValueForEditor()) {
oldValue = Array.get(propValue, arrayIndex);
}
Object convertedValue = this.typeConverterDelegate.convertIfNecessary(
propertyName, oldValue, pv.getValue(), requiredType);
Array.set(propValue, Integer.parseInt(key), convertedValue);
}
catch (IllegalArgumentException ex) {
PropertyChangeEvent pce =
new PropertyChangeEvent(this.rootObject, this.nestedPath + propertyName, oldValue, pv.getValue());
throw new TypeMismatchException(pce, requiredType, ex);
}
catch (IllegalStateException ex) {
PropertyChangeEvent pce =
new PropertyChangeEvent(this.rootObject, this.nestedPath + propertyName, oldValue, pv.getValue());
throw new ConversionNotSupportedException(pce, requiredType, ex);
}
catch (IndexOutOfBoundsException ex) {
throw new InvalidPropertyException(getRootClass(), this.nestedPath + propertyName,
"Invalid array index in property path '" + propertyName + "'", ex);
}
}
else if (propValue instanceof List) {
PropertyDescriptor pd = getCachedIntrospectionResults().getPropertyDescriptor(actualName);
Class requiredType = GenericCollectionTypeResolver.getCollectionReturnType(
pd.getReadMethod(), tokens.keys.length);
List list = (List) propValue;
int index = Integer.parseInt(key);
Object oldValue = null;
if (isExtractOldValueForEditor() && index < list.size()) {
oldValue = list.get(index);
}
try {
Object convertedValue = this.typeConverterDelegate.convertIfNecessary(
propertyName, oldValue, pv.getValue(), requiredType);
if (index < list.size()) {
list.set(index, convertedValue);
}
else if (index >= list.size()) {
for (int i = list.size(); i < index; i++) {
try {
list.add(null);
}
catch (NullPointerException ex) {
throw new InvalidPropertyException(getRootClass(), this.nestedPath + propertyName,
"Cannot set element with index " + index + " in List of size " +
list.size() + ", accessed using property path '" + propertyName +
"': List does not support filling up gaps with null elements");
}
}
list.add(convertedValue);
}
}
catch (IllegalArgumentException ex) {
PropertyChangeEvent pce =
new PropertyChangeEvent(this.rootObject, this.nestedPath + propertyName, oldValue, pv.getValue());
throw new TypeMismatchException(pce, requiredType, ex);
}
}
else if (propValue instanceof Map) {
PropertyDescriptor pd = getCachedIntrospectionResults().getPropertyDescriptor(actualName);
Class mapKeyType = GenericCollectionTypeResolver.getMapKeyReturnType(
pd.getReadMethod(), tokens.keys.length);
Class mapValueType = GenericCollectionTypeResolver.getMapValueReturnType(
pd.getReadMethod(), tokens.keys.length);
Map map = (Map) propValue;
Object convertedMapKey;
Object convertedMapValue;
try {
// IMPORTANT: Do not pass full property name in here - property editors
// must not kick in for map keys but rather only for map values.
convertedMapKey = this.typeConverterDelegate.convertIfNecessary(key, mapKeyType);
}
catch (IllegalArgumentException ex) {
PropertyChangeEvent pce =
new PropertyChangeEvent(this.rootObject, this.nestedPath + propertyName, null, pv.getValue());
throw new TypeMismatchException(pce, mapKeyType, ex);
}
Object oldValue = null;
if (isExtractOldValueForEditor()) {
oldValue = map.get(convertedMapKey);
}
try {
// Pass full property name and old value in here, since we want full
// conversion ability for map values.
convertedMapValue = this.typeConverterDelegate.convertIfNecessary(
propertyName, oldValue, pv.getValue(), mapValueType,
new MethodParameter(pd.getReadMethod(), -1, tokens.keys.length + 1));
}
catch (IllegalArgumentException ex) {
PropertyChangeEvent pce =
new PropertyChangeEvent(this.rootObject, this.nestedPath + propertyName, oldValue, pv.getValue());
throw new TypeMismatchException(pce, mapValueType, ex);
}
map.put(convertedMapKey, convertedMapValue);
}
else {
throw new InvalidPropertyException(getRootClass(), this.nestedPath + propertyName,
"Property referenced in indexed property path '" + propertyName +
"' is neither an array nor a List nor a Map; returned value was [" + pv.getValue() + "]");
}
}
else {
PropertyDescriptor pd = pv.resolvedDescriptor;
if (pd == null || !pd.getWriteMethod().getDeclaringClass().isInstance(this.object)) {
pd = getCachedIntrospectionResults().getPropertyDescriptor(actualName);
if (pd == null || pd.getWriteMethod() == null) {
if (pv.isOptional()) {
logger.debug("Ignoring optional value for property '" + actualName +
"' - property not found on bean class [" + getRootClass().getName() + "]");
return;
}
else {
PropertyMatches matches = PropertyMatches.forProperty(propertyName, getRootClass());
throw new NotWritablePropertyException(
getRootClass(), this.nestedPath + propertyName,
matches.buildErrorMessage(), matches.getPossibleMatches());
}
}
pv.getOriginalPropertyValue().resolvedDescriptor = pd;
}
Object oldValue = null;
try {
Object originalValue = pv.getValue();
Object valueToApply = originalValue;
if (!Boolean.FALSE.equals(pv.conversionNecessary)) {
if (pv.isConverted()) {
valueToApply = pv.getConvertedValue();
}
else {
if (isExtractOldValueForEditor() && pd.getReadMethod() != null) {
final Method readMethod = pd.getReadMethod();
if (!Modifier.isPublic(readMethod.getDeclaringClass().getModifiers()) && !readMethod.isAccessible()) {
if (System.getSecurityManager()!= null) {
AccessController.doPrivileged(new PrivilegedAction<Object>() {
public Object run() {
readMethod.setAccessible(true);
return null;
}
});
}
else {
readMethod.setAccessible(true);
}
}
try {
if (System.getSecurityManager() != null) {
oldValue = AccessController.doPrivileged(new PrivilegedExceptionAction<Object>() {
public Object run() throws Exception {
return readMethod.invoke(object);
}
},acc);
}
else {
oldValue = readMethod.invoke(object);
}
}
catch (Exception ex) {
if (ex instanceof PrivilegedActionException) {
ex = ((PrivilegedActionException) ex).getException();
}
if (logger.isDebugEnabled()) {
logger.debug("Could not read previous value of property '" +
this.nestedPath + propertyName + "'", ex);
}
}
}
valueToApply = this.typeConverterDelegate.convertIfNecessary(oldValue, originalValue, pd);
}
pv.getOriginalPropertyValue().conversionNecessary = (valueToApply != originalValue);
}
final Method writeMethod = pd.getWriteMethod();
if (!Modifier.isPublic(writeMethod.getDeclaringClass().getModifiers()) && !writeMethod.isAccessible()) {
if (System.getSecurityManager()!= null) {
AccessController.doPrivileged(new PrivilegedAction<Object>() {
public Object run() {
writeMethod.setAccessible(true);
return null;
}
});
}
else {
writeMethod.setAccessible(true);
}
}
final Object value = valueToApply;
if (System.getSecurityManager() != null) {
try {
AccessController.doPrivileged(new PrivilegedExceptionAction<Object>() {
public Object run() throws Exception {
writeMethod.invoke(object, value);
return null;
}
}, acc);
} catch (PrivilegedActionException ex) {
throw ex.getException();
}
}
else {
writeMethod.invoke(object, value);
}
}
catch (InvocationTargetException ex) {
PropertyChangeEvent propertyChangeEvent =
new PropertyChangeEvent(this.rootObject, this.nestedPath + propertyName, oldValue, pv.getValue());
if (ex.getTargetException() instanceof ClassCastException) {
throw new TypeMismatchException(propertyChangeEvent, pd.getPropertyType(), ex.getTargetException());
}
else {
throw new MethodInvocationException(propertyChangeEvent, ex.getTargetException());
}
}
catch (ConversionException ex) {
PropertyChangeEvent pce =
new PropertyChangeEvent(this.rootObject, this.nestedPath + propertyName, oldValue, pv.getValue());
throw new TypeMismatchException(pce, pd.getPropertyType(), ex);
}
catch (IllegalArgumentException ex) {
PropertyChangeEvent pce =
new PropertyChangeEvent(this.rootObject, this.nestedPath + propertyName, oldValue, pv.getValue());
throw new TypeMismatchException(pce, pd.getPropertyType(), ex);
}
catch (IllegalStateException ex) {
PropertyChangeEvent pce =
new PropertyChangeEvent(this.rootObject, this.nestedPath + propertyName, oldValue, pv.getValue());
throw new ConversionNotSupportedException(pce, pd.getPropertyType(), ex);
}
catch (IllegalAccessException ex) {
PropertyChangeEvent pce =
new PropertyChangeEvent(this.rootObject, this.nestedPath + propertyName, oldValue, pv.getValue());
throw new MethodInvocationException(pce, ex);
}
catch (Exception ex) {
PropertyChangeEvent pce =
new PropertyChangeEvent(this.rootObject, this.nestedPath + propertyName, oldValue, pv.getValue());
throw new MethodInvocationException(pce, ex);
}
}
}
在这个非常长的方法里面真正完成了依赖注入的实现，对property进行类型的判断（propValue.getClass().isArray()，propValue instanceof List，propValue instanceof Map）然后根据类型分别进行注入处理。到此，依赖注入基本到底。
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发表时间：2010-08-23
最后修改：2010-08-23
LZ太猛了，写这么长的实例，看的都不想看了，找个短点的例子能说明你想表达的内容就OK了！
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发表时间：2010-08-23
Andrew1945 写道 LZ太猛了，写这么长的实例，看的都不想看了，找个短点的例子能说明你想表达的内容就OK了！
看清楚，搂住是在源码分析，不是讲啥是DI！！ |
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发表时间：2010-08-23
一看就是看懂了就往上贴那种~
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发表时间：2010-08-23
这种是装牛的人，拼命的ctrl+c ctrl+v。
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发表时间：2010-08-23
能看懂也不容易啊
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发表时间：2010-08-23
当做学习笔记还可以。
建议：如果是从interface的层面写就更好了，具体实现陷入的太深了，就看不到系统的架构了。 |
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发表时间：2010-08-23
虽然代码很长，但是可以花时间研究研究，看spring是怎么实现注入的。楼主即使是贴，都贴到地方了，也不容易啊。。。顶下。。
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发表时间：2010-08-24
spring 正在学习中.看懂你的代码还是有些费力
要是写多些注释就更好了 |
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发表时间：2010-08-24
很漫长，重点的地方需要用注释说明一下，否则很难全部看完
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