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前两个小节，已经分析了bean属性的解析和转换，转换完之后，就可以应用属性了，我们的实例中用的都是Setter方法注入，那么自然会调用bean属性的set方法对属性进行注入。
打开AbstractAutowireCapableBeanFactory类的applyPropertyValues方法，开始分析
// ⑦设置属性值.
try {
bw.setPropertyValues(new MutablePropertyValues(deepCopy));
}
1. 循环获取到的PropertyValue并设置属性值
public void setPropertyValues(PropertyValues pvs, boolean ignoreUnknown, boolean ignoreInvalid) throws BeansException {
List<PropertyAccessException> propertyAccessExceptions = null;
// 获取当前bean的所有属性值
List<PropertyValue> propertyValues = (pvs instanceof MutablePropertyValues ?
((MutablePropertyValues) pvs).getPropertyValueList() : Arrays.asList(pvs.getPropertyValues()));
// 循环并设置属性值
for (PropertyValue pv : propertyValues) {
try {
// This method may throw any BeansException, which won't be caught
// here, if there is a critical failure such as no matching field.
// We can attempt to deal only with less serious exceptions.
setPropertyValue(pv);
}
catch (NotWritablePropertyException ex) {
if (!ignoreUnknown) {
throw ex;
}
// Otherwise, just ignore it and continue...
}
catch (NullValueInNestedPathException ex) {
if (!ignoreInvalid) {
throw ex;
}
// Otherwise, just ignore it and continue...
}
catch (PropertyAccessException ex) {
if (propertyAccessExceptions == null) {
propertyAccessExceptions = new ArrayList<>();
}
propertyAccessExceptions.add(ex);
}
}
// If we encountered individual exceptions, throw the composite exception.
if (propertyAccessExceptions != null) {
PropertyAccessException[] paeArray = propertyAccessExceptions.toArray(new PropertyAccessException[0]);
throw new PropertyBatchUpdateException(paeArray);
}
}
至此我们已经得到了配置文件中所有PropertyValue的集合，然后通过循环逐步将其值设置到bean中。
2.获取PropertyTokenHolder对象并判断应该设置key-value属性还是本地属性
public void setPropertyValue(PropertyValue pv) throws BeansException {
PropertyTokenHolder tokens = (PropertyTokenHolder) pv.resolvedTokens;
if (tokens == null) {
String propertyName = pv.getName();
AbstractNestablePropertyAccessor nestedPa;
try {
nestedPa = getPropertyAccessorForPropertyPath(propertyName);
}
catch (NotReadablePropertyException ex) {
throw new NotWritablePropertyException(getRootClass(), this.nestedPath + propertyName,
"Nested property in path '" + propertyName + "' does not exist", ex);
}
tokens = getPropertyNameTokens(getFinalPath(nestedPa, propertyName));
if (nestedPa == this) {
pv.getOriginalPropertyValue().resolvedTokens = tokens;
}
nestedPa.setPropertyValue(tokens, pv);
}
else {
setPropertyValue(tokens, pv);
}
}
protected void setPropertyValue(PropertyTokenHolder tokens, PropertyValue pv) throws BeansException {
// 设置配置文件中的key:value对,例如.propertis中的属性
if (tokens.keys != null) {
processKeyedProperty(tokens, pv);
}
// 设置本地属性
else {
processLocalProperty(tokens, pv);
}
}
3.设置本地属性
private void processLocalProperty(PropertyTokenHolder tokens, PropertyValue pv) {
PropertyHandler ph = getLocalPropertyHandler(tokens.actualName);
// PropertyHandler为null,或者方法不可写的时候.
if (ph == null || !ph.isWritable()) {
//返回是否为可选值，即在目标类上不存在相应的属性时将被忽略。
if (pv.isOptional()) {
return;
}
else {
throw createNotWritablePropertyException(tokens.canonicalName);
}
}
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() && ph.isReadable()) {
try {
oldValue = ph.getValue();
}
// 省略异常打印信息...
catch (Exception ex) {}
}
valueToApply = convertForProperty(tokens.canonicalName, oldValue, originalValue, ph.toTypeDescriptor());
}
pv.getOriginalPropertyValue().conversionNecessary = (valueToApply != originalValue);
}
// 设置属性
ph.setValue(valueToApply);
}
catch (TypeMismatchException ex) {
throw ex;
}
catch (InvocationTargetException ex) {
PropertyChangeEvent propertyChangeEvent = new PropertyChangeEvent(
getRootInstance(), this.nestedPath + tokens.canonicalName, oldValue, pv.getValue());
if (ex.getTargetException() instanceof ClassCastException) {
throw new TypeMismatchException(propertyChangeEvent, ph.getPropertyType(), ex.getTargetException());
}
else {
Throwable cause = ex.getTargetException();
if (cause instanceof UndeclaredThrowableException) {
// May happen e.g. with Groovy-generated methods
cause = cause.getCause();
}
throw new MethodInvocationException(propertyChangeEvent, cause);
}
}
catch (Exception ex) {
PropertyChangeEvent pce = new PropertyChangeEvent(getRootInstance(), this.nestedPath + tokens.canonicalName, oldValue, pv.getValue());
throw new MethodInvocationException(pce, ex);
}
}
4.设置属性
public void setValue(final @Nullable Object value) throws Exception {
// 获取可写方法，例如javaBean中的setXXX()方法
final Method writeMethod = (this.pd instanceof GenericTypeAwarePropertyDescriptor ?
((GenericTypeAwarePropertyDescriptor) this.pd).getWriteMethodForActualAccess() :
this.pd.getWriteMethod());
if (System.getSecurityManager() != null) {
AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
ReflectionUtils.makeAccessible(writeMethod);
return null;
});
try {
AccessController.doPrivileged((PrivilegedExceptionAction<Object>) () ->
writeMethod.invoke(getWrappedInstance(), value), acc);
}
catch (PrivilegedActionException ex) {
throw ex.getException();
}
}
else {
ReflectionUtils.makeAccessible(writeMethod);
// 调用Method方法的invoke方法,通过反射方法为bean设置值
writeMethod.invoke(getWrappedInstance(), value);
}
}
5.总结
设置属性的大体流程还是比较简单的，首先获取已经转换的所有的配置文件中bean的属性；然后循环获取到的属性为javaBean设置值；获取javaBean的可写方法；通过Method的invoke方法，利用java的反射机制为javaBean设置值。