add serveral ways to configure beans in java readme

Author: ipipman

springboot-source-code-analysis/(11)通过Java配置Bean的几种方式.md

@@ -17,11 +17,17 @@
 @Component
 public class MyFactoryBean implements FactoryBean<Animal> {
 
+/**
+* 返回要注入的类
+*/
 @Override
 public Animal getObject() throws Exception {
 return new Cat();
 }
 
+/**
+* 获取要注入类的类型
+*/
 @Override
 public Class<?> getObjectType() {
 return Animal.class;
@@ -31,4 +37,5 @@ public Class<?> getObjectType() {
 public boolean isSingleton() {
 return FactoryBean.super.isSingleton();
 }
+
 }

springboot-source-code-analysis/src/main/java/com/example/springboot/source/code/analysis/ioc/ann/MyFactoryBean.java

@@ -0,0 +1,98 @@
+### 通过Java配置Bean的几种方式
+
+#### 1.通过@Configuration注解注入Bean的方式
+
+```java
+@Configuration
+public class MyBeanConfiguration {
+
+/**
+* 通过 @Configuration注解 注入一个Bean
+*/
+@Bean("dog")
+public Animal getDog() {
+return new Dog();
+}
+
+}
+```
+
+
+
+#### 2.通过实现FactoryBean<?>接口的方式注入Bean
+
+```java
+@Component
+public class MyFactoryBean implements FactoryBean<Animal> {
+
+/**
+* 返回要注入的类
+*/
+@Override
+public Animal getObject() throws Exception {
+return new Cat();
+}
+
+/**
+* 获取要注入类的类型
+*/
+@Override
+public Class<?> getObjectType() {
+return Animal.class;
+}
+
+@Override
+public boolean isSingleton() {
+return FactoryBean.super.isSingleton();
+}
+
+}
+```
+
+
+
+#### 3.通过实现BeanDefinitionRegistryPostProcessor接口的方式注入Bean
+
+```java
+@Component
+public class MyBeanDefinitionRegistry implements BeanDefinitionRegistryPostProcessor {
+
+/**
+* 通过BeanDefinitionRegistryPostProcessor
+*/
+@Override
+public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry beanDefinitionRegistry) throws BeansException {
+RootBeanDefinition rootBeanDefinition = new RootBeanDefinition();
+rootBeanDefinition.setBeanClass(Monkey.class);
+beanDefinitionRegistry.registerBeanDefinition("monkey", rootBeanDefinition);
+}
+
+@Override
+public void postProcessBeanFactory(ConfigurableListableBeanFactory configurableListableBeanFactory) throws BeansException {
+
+}
+}
+```
+
+
+
+#### 4.通过实现ImportBeanDefinitionRegistrar接口的方式注入Bean
+
+```java
+public class MyImportBeanDefinitionRegistrar implements ImportBeanDefinitionRegistrar {
+
+/**
+* 通过ImportBeanDefinitionRegistrar注入Bean
+*/
+@Override
+public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
+RootBeanDefinition rootBeanDefinition = new RootBeanDefinition();
+rootBeanDefinition.setBeanClass(Bird.class);
+registry.registerBeanDefinition("bird", rootBeanDefinition);
+}
+}
+
+```
+
+> 使用时：用 @Import(MyImportBeanDefinitionRegistrar.class) 进行注入
+