spring IoC （六）autowiring(自动依赖装配)的实现
2021-06-16 00:03
标签：sem || val str == 通过 方式 构造 pop 在前面对IoC容器实现原理的分析中，一直是通过BeanDefinition的属性值和构造函数以显式的方式对Bean 的依赖关系进行管理的。在Spring中，相对这种显式的依赖管理方式，IoC容器还提供了自动依赖装配的方式， 为应用使用容器提供更大的方便。在自动装配中，不需要对Bean属性做显式的依赖关系声明，只需要配置好 autowiring属性，IoC容器会根据这个属性的配置，使用反射自动查找属性的类型或者名字，然后基于属性的 类型或名字来自动匹配IoC容器中的Bean，从而自动的完成依赖注入。 在AbstractAutowireCapableBeanFactory.populateBean(String, RootBeanDefinition, BeanWrapper)方法中 如果当前的Bean配置了autowire_by_name和autowire_by_type属性，那么调用相应的autowireByName和 autowireByType方法。 spring IoC （六）autowiring(自动依赖装配)的实现 标签：sem || val str == 通过 方式 构造 pop 原文地址：https://www.cnblogs.com/toUpdating/p/9728638.html 1 protected void populateBean(String beanName, RootBeanDefinition mbd, BeanWrapper bw) {
2 PropertyValues pvs = mbd.getPropertyValues();
3
4 if (bw == null) {
5 if (!pvs.isEmpty()) {
6 throw new BeanCreationException(
7 mbd.getResourceDescription(), beanName, "Cannot apply property values to null instance");
8 }
9 else {
10 // Skip property population phase for null instance.
11 return;
12 }
13 }
14
15 // Give any InstantiationAwareBeanPostProcessors the opportunity to modify the
16 // state of the bean before properties are set. This can be used, for example,
17 // to support styles of field injection.
18 boolean continueWithPropertyPopulation = true;
19
20 if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {
21 for (BeanPostProcessor bp : getBeanPostProcessors()) {
22 if (bp instanceof InstantiationAwareBeanPostProcessor) {
23 InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
24 if (!ibp.postProcessAfterInstantiation(bw.getWrappedInstance(), beanName)) {
25 continueWithPropertyPopulation = false;
26 break;
27 }
28 }
29 }
30 }
31
32 if (!continueWithPropertyPopulation) {
33 return;
34 }
35
36 if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_NAME ||
37 mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_TYPE) {
38 MutablePropertyValues newPvs = new MutablePropertyValues(pvs);
39
40 // Add property values based on autowire by name if applicable.
41 if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_NAME) {
42 autowireByName(beanName, mbd, bw, newPvs);
43 }
44
45 // Add property values based on autowire by type if applicable.
46 if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_TYPE) {
47 autowireByType(beanName, mbd, bw, newPvs);
48 }
49
50 pvs = newPvs;
51 }
52
53 boolean hasInstAwareBpps = hasInstantiationAwareBeanPostProcessors();
54 boolean needsDepCheck = (mbd.getDependencyCheck() != RootBeanDefinition.DEPENDENCY_CHECK_NONE);
55
56 if (hasInstAwareBpps || needsDepCheck) {
57 PropertyDescriptor[] filteredPds = filterPropertyDescriptorsForDependencyCheck(bw, mbd.allowCaching);
58 if (hasInstAwareBpps) {
59 for (BeanPostProcessor bp : getBeanPostProcessors()) {
60 if (bp instanceof InstantiationAwareBeanPostProcessor) {
61 InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
62 pvs = ibp.postProcessPropertyValues(pvs, filteredPds, bw.getWrappedInstance(), beanName);
63 if (pvs == null) {
64 return;
65 }
66 }
67 }
68 }
69 if (needsDepCheck) {
70 checkDependencies(beanName, mbd, filteredPds, pvs);
71 }
72 }
73
74 applyPropertyValues(beanName, mbd, bw, pvs);
75 }
文章标题：spring IoC （六）autowiring(自动依赖装配)的实现
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