• 深入浅出Spring（23）

    参考链接1

    Spring bean生命周期

    1. 阶段1：Bean元信息配置阶段
    2. 阶段2：Bean元信息解析阶段
    3. 阶段3：将Bean注册到容器中
    4. 阶段4：BeanDefinition合并阶段
    5. 阶段5：Bean Class加载阶段
    6. 阶段6：Bean实例化阶段
    7. 阶段7：合并后的BeanDefinition处理
    8. 阶段8：属性赋值阶段
    9. 阶段9：Bean初始化阶段
    10. 阶段10：所有单例bean初始化完成后阶段
    11. 阶段11：Bean的使用阶段
    12. 阶段12：Bean销毁前阶段
    13. 阶段13：Bean销毁阶段

    阶段6分为

    1. Bean实例化前阶段
    2. Bean实例化阶段

    阶段8分为

    1. Bean实例化后阶段
    2. Bean属性赋值前阶段.
    3. Bean属性赋值阶段

    阶段9分为

    1. Bean Aware接口回调阶段
    2. Bean初始化前阶段
    3. Bean初始化阶段
    4. Bean初始化后阶段

    阶段1：Bean元信息配置阶段

    Bean信息定义4种方式

    主要包括xml，@Bean，properties文件，接口

    接口

    案例1：组装一个简单的bean

    public class Car {
    private String name;
	//省略get、set、toStirng
}

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    public class Client {
    public static void main(String[] args) {
        BeanDefinitionBuilder beanDefinitionBuilder = 
        BeanDefinitionBuilder.rootBeanDefinition(Car.class.getName());
        BeanDefinition beanDefinition = beanDefinitionBuilder.getBeanDefinition();
        System.out.println(beanDefinition);
    }
}

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    输出

    Root bean: class [com.example.lurenjia.spring.c22.d1.Car];
scope=; abstract=false; lazyInit=null; autowireMode=0; dependencyCheck=0;
autowireCandidate=true; primary=false; factoryBeanName=null; factoryMethodName=null;
initMethodName=null; destroyMethodName=null

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    案例2：组装一个有属性的bean

    public class Client2 {
    public static void main(String[] args) {
        BeanDefinitionBuilder beanDefinitionBuilder = 
        BeanDefinitionBuilder.rootBeanDefinition(Car.class.getName());
        beanDefinitionBuilder.addPropertyValue("name", "奥迪");
        BeanDefinition carBeanDefinition = beanDefinitionBuilder.getBeanDefinition();
        System.out.println(carBeanDefinition);
        System.out.println("----");
        DefaultListableBeanFactory factory = new DefaultListableBeanFactory();
        factory.registerBeanDefinition("car", carBeanDefinition);
        Car bean = factory.getBean("car", Car.class);
        System.out.println(bean);
    }
}

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    输出

    Root bean: class [com.example.lurenjia.spring.c22.jd1.d1.Car]; scope=; abstract=false; lazyInit=null;
 autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=null; 
 factoryMethodName=null; initMethodName=null; destroyMethodName=null
----
Creating shared instance of singleton bean 'car'
Car{name='奥迪'}

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    案例3：组装一个有依赖关系的bean

    public class User {

    private String name;

    private Car car;
	//省略get、set、toStirng
}

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    public class Client3 {
    public static void main(String[] args) {
        BeanDefinition carBeanDefinition = BeanDefinitionBuilder.rootBeanDefinition(Car.class.getName()).addPropertyValue("name", "奥迪").getBeanDefinition();
        BeanDefinition userBeanDefinition = BeanDefinitionBuilder.rootBeanDefinition(User.class.getName()).
                addPropertyValue("name", "路人甲Java").
                addPropertyReference("car", "car").
                getBeanDefinition();
        DefaultListableBeanFactory factory = new DefaultListableBeanFactory();
        factory.registerBeanDefinition("car", carBeanDefinition);
        factory.registerBeanDefinition("user", userBeanDefinition);
        System.out.println(factory.getBean("car"));
        System.out.println(factory.getBean("user"));
    }
}

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    Car{name='奥迪'}
User{name='路人甲Java', car=Car{name='奥迪'}}

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    案例4：来2个有父子关系的bean

    public class Client4 {
    public static void main(String[] args) {
        BeanDefinition carBeanDefinition1 = BeanDefinitionBuilder.
                genericBeanDefinition(Car.class).
                addPropertyValue("name", "保时捷").
                getBeanDefinition();

        BeanDefinition carBeanDefinition2 = BeanDefinitionBuilder.
                genericBeanDefinition().
                setParentName("car1").
                getBeanDefinition();
        DefaultListableBeanFactory factory = new DefaultListableBeanFactory();
        factory.registerBeanDefinition("car1", carBeanDefinition1);
        factory.registerBeanDefinition("car2", carBeanDefinition2);
        System.out.println(String.format("car1->%s", factory.getBean("car1")));
        System.out.println(String.format("car2->%s", factory.getBean("car2")));
    }
}

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    car1->Car{name='保时捷'}
car2->Car{name='保时捷'}

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    案例5：通过api设置（Map、Set、List）属性

    public class CompositeObj {

    private String name;
    private Integer salary;

    private Car car1;
    private List<String> stringList;
    private List<Car> carList;

    private Set<String> stringSet;
    private Set<Car> carSet;

    private java.util.Map<String, String> stringMap;
    private java.util.Map<String, Car> stringCarMap;

    //省略get set tostring
}

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    public class Client {
    public static void main(String[] args) {
        //定义car1
        BeanDefinition car1 = BeanDefinitionBuilder.
                genericBeanDefinition(Car.class).
                addPropertyValue("name", "奥迪").
                getBeanDefinition();
        //定义car2
        BeanDefinition car2 = BeanDefinitionBuilder.
                genericBeanDefinition(Car.class).
                addPropertyValue("name", "保时捷").
                getBeanDefinition();

        //定义CompositeObj这个bean
        //创建stringList这个属性对应的值
        ManagedList<String> stringList = new ManagedList<>();
        stringList.addAll(Arrays.asList("java高并发系列", "mysql系列", "maven高手系列"));

        //创建carList这个属性对应的值,内部引用其他两个bean的名称[car1,car2]
        ManagedList<RuntimeBeanReference> carList = new ManagedList<>();
        carList.add(new RuntimeBeanReference("car1"));
        carList.add(new RuntimeBeanReference("car2"));

        //创建stringList这个属性对应的值
        ManagedSet<String> stringSet = new ManagedSet<>();
        stringSet.addAll(Arrays.asList("java高并发系列", "mysql系列", "maven高手系列"));

        //创建carSet这个属性对应的值,内部引用其他两个bean的名称[car1,car2]
        ManagedList<RuntimeBeanReference> carSet = new ManagedList<>();
        carSet.add(new RuntimeBeanReference("car1"));
        carSet.add(new RuntimeBeanReference("car2"));

        //创建stringMap这个属性对应的值
        ManagedMap<String, String> stringMap = new ManagedMap<>();
        stringMap.put("系列1", "java高并发系列");
        stringMap.put("系列2", "Maven高手系列");
        stringMap.put("系列3", "mysql系列");

        ManagedMap<String, RuntimeBeanReference> stringCarMap = new ManagedMap<>();
        stringCarMap.put("car1", new RuntimeBeanReference("car1"));
        stringCarMap.put("car2", new RuntimeBeanReference("car2"));


        //下面我们使用原生的api来创建BeanDefinition
        GenericBeanDefinition compositeObj = new GenericBeanDefinition();
        compositeObj.setBeanClassName(CompositeObj.class.getName());
        compositeObj.getPropertyValues().add("name", "路人甲Java").
                add("salary", 50000).
                add("car1", new RuntimeBeanReference("car1")).
                add("stringList", stringList).
                add("carList", carList).
                add("stringSet", stringSet).
                add("carSet", carSet).
                add("stringMap", stringMap).
                add("stringCarMap", stringCarMap);

        //将上面bean 注册到容器
        DefaultListableBeanFactory factory = new DefaultListableBeanFactory();
        factory.registerBeanDefinition("car1", car1);
        factory.registerBeanDefinition("car2", car2);
        factory.registerBeanDefinition("compositeObj", compositeObj);

        //下面我们将容器中所有的bean输出
        for (String beanName : factory.getBeanDefinitionNames()) {
            System.out.println(String.format("%s->%s", beanName, factory.getBean(beanName)));
        }
    }
}

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    xml

    <?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="helloWorld" class="com.example.lurenjia.spring.c3.HelloWorld"/>

</beans>

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    xml中的bean配置信息会被解析器解析为BeanDefinition对象，一会在第二阶段详解。

    properties文件的方式

    参照阶段2解析里面properties文件定义内容

    注解的方式

    类上标注@Compontent注解来定义一个bean

    示例省略

    配置类中使用@Bean注解来定义bean

    示例省略

    阶段2：Bean元信息解析阶段

    目的：将阶段1各种方式的定义解析为 BeanDefinition 对象

    XML方式解析：XmlBeanDefinitionReader

    
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
       
    <bean id="helloWorld" class="com.example.lurenjia.spring.c3.HelloWorld"/>

beans>

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    public class Client {
    public static void main(String[] args) {
        DefaultListableBeanFactory factory = new DefaultListableBeanFactory();
        XmlBeanDefinitionReader xmlBeanDefinitionReader = new XmlBeanDefinitionReader(factory);
        String location = "classpath:beans3.xml";
        int countBean = xmlBeanDefinitionReader.loadBeanDefinitions(location);
        System.out.println(String.format("共注册了 %s 个bean", countBean));
        for (String beanName : factory.getBeanDefinitionNames()) {
            BeanDefinition beanDefinition = factory.getBeanDefinition(beanName);
            String beanDefinitionClassName = beanDefinition.getClass().getName();
            Object bean = factory.getBean(beanName);
            System.out.println(beanName + ":");
            System.out.println("    beanDefinitionClassName：" + beanDefinitionClassName);
            System.out.println("    beanDefinition：" + beanDefinition);
            System.out.println("    bean：" + bean);
        }
    }
}

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    共注册了 1 个bean
helloWorld:
    beanDefinitionClassName：org.springframework.beans.factory.support.GenericBeanDefinition
    beanDefinition：Generic bean: class [com.example.lurenjia.spring.c3.HelloWorld]; scope=; abstract=false; 
    lazyInit=false; autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; 
    factoryBeanName=null; factoryMethodName=null; initMethodName=null; destroyMethodName=null; 
    defined in class path resource [beans3.xml]
    bean：com.example.lurenjia.spring.c3.HelloWorld@51565ec2

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    properties文件定义bean的解析：PropertiesBeanDefinitionReader

    官方示例

       employee.(class)=MyClass       // bean is of class MyClass
   employee.(abstract)=true       // this bean can't be instantiated directly
   employee.group=Insurance       // real property
   employee.usesDialUp=false      // real property (potentially overridden)
  
   salesrep.(parent)=employee     // derives from "employee" bean definition
   salesrep.(lazy-init)=true      // lazily initialize this singleton bean
   salesrep.manager(ref)=tony     // reference to another bean
   salesrep.department=Sales      // real property
  
   techie.(parent)=employee       // derives from "employee" bean definition
   techie.(scope)=prototype       // bean is a prototype (not a shared instance)
   techie.manager(ref)=jeff       // reference to another bean
   techie.department=Engineering  // real property
   techie.usesDialUp=true         // real property (overriding parent value)
  
   ceo.$0(ref)=secretary          // inject 'secretary' bean as 0th constructor arg
   ceo.$1=1000000                 // inject value '1000000' at 1st constructor arg

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    我们在resource目录下创建一个beans.properties

    car.(class)=com.example.lurenjia.spring.c22.jd1.d1.Car
car.name=name1

car1.(class)=com.example.lurenjia.spring.c22.jd1.d1.Car
car1.name=name2

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    public class Client {
    public static void main(String[] args) {
        DefaultListableBeanFactory factory = new DefaultListableBeanFactory();
        PropertiesBeanDefinitionReader propertiesBeanDefinitionReader = new PropertiesBeanDefinitionReader(factory);
        String location = "classpath:beans.properties";
        int countBean = propertiesBeanDefinitionReader.loadBeanDefinitions(location);
        System.out.println(String.format("共注册了 %s 个bean", countBean));
        for (String beanName : factory.getBeanDefinitionNames()) {
            BeanDefinition beanDefinition = factory.getBeanDefinition(beanName);
            String beanDefinitionClassName = beanDefinition.getClass().getName();
            Object bean = factory.getBean(beanName);
            System.out.println(beanName + ":");
            System.out.println("    beanDefinitionClassName：" + beanDefinitionClassName);
            System.out.println("    beanDefinition：" + beanDefinition);
            System.out.println("    bean：" + bean);
        }
    }
}

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    在这里插入图片描述

    注解方式：PropertiesBeanDefinitionReader

    @Scope(ConfigurableBeanFactory.SCOPE_PROTOTYPE)
@Primary
@Lazy
public class Service1 {
}

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    public class Service2 {

    @Autowired
    private Service1 service1;

    @Override
    public String toString() {
        return "Service2{" +
                "service1=" + service1 +
                '}';
    }
}

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    public class Client {
    public static void main(String[] args) {
        DefaultListableBeanFactory factory = new DefaultListableBeanFactory();
        AnnotatedBeanDefinitionReader annotatedBeanDefinitionReader = new AnnotatedBeanDefinitionReader(factory);
        annotatedBeanDefinitionReader.register(Service1.class, Service2.class);
        for (String beanName : new String[]{"service1", "service2"}) {
            BeanDefinition beanDefinition = factory.getBeanDefinition(beanName);
            String beanDefinitionClassName = beanDefinition.getClass().getName();
            Object bean = factory.getBean(beanName);
            System.out.println(beanName + ":");
            System.out.println("    beanDefinitionClassName：" + beanDefinitionClassName);
            System.out.println("    beanDefinition：" + beanDefinition);
            System.out.println("    bean：" + bean);
        }
    }
}

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    在这里插入图片描述
    这里为什么会输出一个null呢

    在 for 循环上面添加一行代码

            factory.getBeansOfType(BeanPostProcessor.class).values().forEach(factory::addBeanPostProcessor);

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    在这里插入图片描述

    阶段3：Spring Bean注册阶段

    一个重要的接口 BeanDefinitionRegistry

    BeanDefinitionRegistry源码

    public interface BeanDefinitionRegistry extends AliasRegistry {
	//注册bean定义
	void registerBeanDefinition(String beanName, BeanDefinition beanDefinition)
			throws BeanDefinitionStoreException;
	//移除bean定义
	void removeBeanDefinition(String beanName) throws NoSuchBeanDefinitionException;
	//获取bean定义
	BeanDefinition getBeanDefinition(String beanName) throws NoSuchBeanDefinitionException;
	//是否包含bean定义
	boolean containsBeanDefinition(String beanName);
	//获取bean定义名称
	String[] getBeanDefinitionNames();
	//获取bean定义数量
	int getBeanDefinitionCount();
	//beanName是否已经注册
	boolean isBeanNameInUse(String beanName);
}

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    AliasRegistry

    AliasRegistry 是 BeanDefinitionRegistry 的父接口

    public interface AliasRegistry {
	//注册别名
	void registerAlias(String name, String alias);
	//移除别名
	void removeAlias(String alias);
	//判断是不是别名
	boolean isAlias(String name);
	//获取别名数组
	String[] getAliases(String name);
}

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    BeanDefinitionRegistry实现类

    DefaultListableBeanFactory

    public class Client {
    public static void main(String[] args) {
        DefaultListableBeanFactory factory = new DefaultListableBeanFactory();
        GenericBeanDefinition nameBdf = new GenericBeanDefinition();
        nameBdf.setBeanClass(String.class);
        nameBdf.getConstructorArgumentValues().addIndexedArgumentValue(0, "abcdefg");
        factory.registerBeanDefinition("name", nameBdf);
        System.out.println(factory.getBeanDefinition("name"));
        System.out.println(factory.containsBeanDefinition("name"));
        System.out.println(Arrays.asList(factory.getBeanDefinitionNames()));
        System.out.println(factory.getBeanDefinitionCount());
        System.out.println(factory.isBeanNameInUse("name"));
        factory.registerAlias("name", "alias-name-1");
        factory.registerAlias("name", "alias-name-2");
        System.out.println(factory.isAlias("alias-name-1"));
        System.out.println(Arrays.asList(factory.getAliases("name")));
        System.out.println(factory.getBean("name"));
    }
}

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    Generic bean: class [java.lang.String]; scope=; abstract=false; lazyInit=null; autowireMode=0; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=null; factoryMethodName=null; initMethodName=null; destroyMethodName=null
true
[name]
1
true
true
[alias-name-2, alias-name-1]
10:25:45.492 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'name'
abcdefg

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    阶段4：BeanDefinition合并阶段

    目的：

    案例

    public class LessonModel {

    private String name;

    private int lessonCount;

    private String description;
    //省略get set tostring

}

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    定义xml文件

    <?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="lesson1" class="com.example.lurenjia.spring.c22.jd4.LessonModel"/>

    <bean id="lesson2" parent="lesson1">
        <property name="name" value="spring高手系列"/>
        <property name="lessonCount" value="100"/>
    </bean>

    <bean id="lesson3" parent="lesson2">
        <property name="description" value="路人甲Java带你学spring，超越90%开发者!"/>
    </bean>
</beans>

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    public class Client {
    public static void main(String[] args) {
        DefaultListableBeanFactory factory = new DefaultListableBeanFactory();
        XmlBeanDefinitionReader beanDefinitionReader = new XmlBeanDefinitionReader(factory);
        beanDefinitionReader.loadBeanDefinitions("classpath:c22jd4d1.xml");
        for (String beanName : factory.getBeanDefinitionNames()) {
            BeanDefinition beanDefinition = factory.getBeanDefinition(beanName);
            BeanDefinition mergedBeanDefinition = factory.getMergedBeanDefinition(beanName);
            System.out.println(beanName);
            System.out.println("解析xml过程中注册的beanDefinition：" + beanDefinition);
            System.out.println("beanDefinition中的属性信息" + beanDefinition.getPropertyValues());
            System.out.println("合并之后得到的mergedBeanDefinition：" + mergedBeanDefinition);
            System.out.println("mergedBeanDefinition中的属性信息" + mergedBeanDefinition.getPropertyValues());
            System.out.println("---------------------------");
        }
    }
}

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    lesson3
解析xml过程中注册的beanDefinition：Generic bean with parent 'lesson2': 
class [null]; scope=; abstract=false; lazyInit=false; autowireMode=0; dependencyCheck=0; 
autowireCandidate=true; primary=false; factoryBeanName=null; factoryMethodName=null;
 initMethodName=null; destroyMethodName=null; defined in class path resource [c22jd4d1.xml]
beanDefinition中的属性信息PropertyValues: length=1; bean property 'description'
合并之后得到的mergedBeanDefinition：Root bean: class [com.example.lurenjia.spring.c22.jd4.LessonModel]; 
scope=singleton; abstract=false; lazyInit=false; autowireMode=0; dependencyCheck=0; autowireCandidate=true; 
primary=false; factoryBeanName=null; factoryMethodName=null; initMethodName=null; destroyMethodName=null; 
defined in class path resource [c22jd4d1.xml]
mergedBeanDefinition中的属性信息PropertyValues: length=3; bean property 'name'; bean property 'lessonCount';
bean property 'description'

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    阶段5：Bean Class加载阶段 （resolveBeanClass）

    Resolve the bean class for the specified bean definition, resolving a bean class name into a Class reference (if necessary) and storing the resolved Class in the bean definition for further use.

    将 bean definition 解析为 bean class.

    	@Nullable
	protected Class<?> resolveBeanClass(RootBeanDefinition mbd, String beanName, Class<?>... typesToMatch)
			throws CannotLoadBeanClassException {

		try {
			if (mbd.hasBeanClass()) {
				return mbd.getBeanClass();
			}
			if (System.getSecurityManager() != null) {
				return AccessController.doPrivileged((PrivilegedExceptionAction<Class<?>>)
						() -> doResolveBeanClass(mbd, typesToMatch), getAccessControlContext());
			}
			else {
				return doResolveBeanClass(mbd, typesToMatch);
			}
		}
		catch (PrivilegedActionException pae) {
			ClassNotFoundException ex = (ClassNotFoundException) pae.getException();
			throw new CannotLoadBeanClassException(mbd.getResourceDescription(), beanName, mbd.getBeanClassName(), ex);
		}
		catch (ClassNotFoundException ex) {
			throw new CannotLoadBeanClassException(mbd.getResourceDescription(), beanName, mbd.getBeanClassName(), ex);
		}
		catch (LinkageError err) {
			throw new CannotLoadBeanClassException(mbd.getResourceDescription(), beanName, mbd.getBeanClassName(), err);
		}
	}

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    阶段6：Bean实例化阶段

    createBean方法

    		try {
			// Give BeanPostProcessors a chance to return a proxy instead of the target bean instance.
			Object bean = resolveBeforeInstantiation(beanName, mbdToUse);
			if (bean != null) {
				return bean;
			}
		}

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    resolveBeforeInstantiation

    	@Nullable
	protected Object resolveBeforeInstantiation(String beanName, RootBeanDefinition mbd) {
		Object bean = null;
		if (!Boolean.FALSE.equals(mbd.beforeInstantiationResolved)) {
			// Make sure bean class is actually resolved at this point.
			if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {
				Class<?> targetType = determineTargetType(beanName, mbd);
				if (targetType != null) {
					bean = applyBeanPostProcessorsBeforeInstantiation(targetType, beanName);
					if (bean != null) {
						bean = applyBeanPostProcessorsAfterInitialization(bean, beanName);
					}
				}
			}
			mbd.beforeInstantiationResolved = (bean != null);
		}
		return bean;
	}

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    	@Nullable
	protected Object applyBeanPostProcessorsBeforeInstantiation(Class<?> beanClass, String beanName) {
		for (InstantiationAwareBeanPostProcessor bp : getBeanPostProcessorCache().instantiationAware) {
			Object result = bp.postProcessBeforeInstantiation(beanClass, beanName);
			if (result != null) {
				return result;
			}
		}
		return null;
	}

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    阶段7：合并后的BeanDefinition处理

    doCreateBean类583行applyMergedBeanDefinitionPostProcessors

    		// Allow post-processors to modify the merged bean definition. 
		synchronized (mbd.postProcessingLock) {
			if (!mbd.postProcessed) {
				try {
					applyMergedBeanDefinitionPostProcessors(mbd, beanType, beanName);
				}
				catch (Throwable ex) {
					throw new BeanCreationException(mbd.getResourceDescription(), beanName,
							"Post-processing of merged bean definition failed", ex);
				}
				mbd.postProcessed = true;
			}
		}

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    applyMergedBeanDefinitionPostProcessors

    	protected void applyMergedBeanDefinitionPostProcessors(RootBeanDefinition mbd, Class<?> beanType, String beanName) {
		for (MergedBeanDefinitionPostProcessor processor : getBeanPostProcessorCache().mergedDefinition) {
			processor.postProcessMergedBeanDefinition(mbd, beanType, beanName);
		}
	}

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    postProcessMergedBeanDefinition是MergedBeanDefinitionPostProcessor接口的方法

    	void postProcessMergedBeanDefinition(RootBeanDefinition beanDefinition, Class<?> beanType, String beanName);

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    主要实现类 todo

    阶段8：Bean属性设置阶段

    		// Initialize the bean instance. 初始化bean实例
		Object exposedObject = bean;
		try {
			//填充bean，涉及阶段8
			populateBean(beanName, mbd, instanceWrapper);
			//初始化bean，涉及阶段9
			exposedObject = initializeBean(beanName, exposedObject, mbd);
		}

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    populateBean方法源码

    	protected void populateBean(String beanName, RootBeanDefinition mbd, @Nullable BeanWrapper bw) {
		//如果BeanWrapper为空
		if (bw == null) {
			if (mbd.hasPropertyValues()) {
				throw new BeanCreationException(
						mbd.getResourceDescription(), beanName, "Cannot apply property values to null instance");
			}
			//当mbd.hasPropertyValues()返回false
			else {
				// Skip property population phase for null instance. 跳过这个阶段
				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.
		if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {
			for (InstantiationAwareBeanPostProcessor bp : getBeanPostProcessorCache().instantiationAware) {
				//如果postProcessAfterInstantiation返回false则跳过该阶段
				if (!bp.postProcessAfterInstantiation(bw.getWrappedInstance(), beanName)) {
					return;
				}
			}
		}
		//PropertyValues 
		PropertyValues pvs = (mbd.hasPropertyValues() ? mbd.getPropertyValues() : null);

		int resolvedAutowireMode = mbd.getResolvedAutowireMode();
		if (resolvedAutowireMode == AUTOWIRE_BY_NAME || resolvedAutowireMode == AUTOWIRE_BY_TYPE) {
			MutablePropertyValues newPvs = new MutablePropertyValues(pvs);
			// Add property values based on autowire by name if applicable.
			if (resolvedAutowireMode == AUTOWIRE_BY_NAME) {
				autowireByName(beanName, mbd, bw, newPvs);
			}
			// Add property values based on autowire by type if applicable.
			if (resolvedAutowireMode == AUTOWIRE_BY_TYPE) {
				autowireByType(beanName, mbd, bw, newPvs);
			}
			pvs = newPvs;
		}

		boolean hasInstAwareBpps = hasInstantiationAwareBeanPostProcessors();
		boolean needsDepCheck = (mbd.getDependencyCheck() != AbstractBeanDefinition.DEPENDENCY_CHECK_NONE);

		PropertyDescriptor[] filteredPds = null;
		if (hasInstAwareBpps) {
			if (pvs == null) {
				pvs = mbd.getPropertyValues();
			}
			//阶段2
			for (InstantiationAwareBeanPostProcessor bp : getBeanPostProcessorCache().instantiationAware) {
				PropertyValues pvsToUse = bp.postProcessProperties(pvs, bw.getWrappedInstance(), beanName);
				if (pvsToUse == null) {
					if (filteredPds == null) {
						filteredPds = filterPropertyDescriptorsForDependencyCheck(bw, mbd.allowCaching);
					}
					pvsToUse = bp.postProcessPropertyValues(pvs, filteredPds, bw.getWrappedInstance(), beanName);
					if (pvsToUse == null) {
						return;
					}
				}
				pvs = pvsToUse;
			}
		}
		if (needsDepCheck) {
			if (filteredPds == null) {
				filteredPds = filterPropertyDescriptorsForDependencyCheck(bw, mbd.allowCaching);
			}
			checkDependencies(beanName, mbd, filteredPds, pvs);
		}

		if (pvs != null) {
			applyPropertyValues(beanName, mbd, bw, pvs);
		}
	}

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    阶段9：Bean初始化阶段（初始化）

    包含阶段

    这个阶段含有几个小阶段

    • Bean Aware接口回调

    • Bean初始化前

    • Bean初始化

    • Bean初始化后

    主要原理 initializeBean 方法执行过程

    AbstractAutowireCapableBeanFactory类609行

    		exposedObject = initializeBean(beanName, exposedObject, mbd);

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    AbstractAutowireCapableBeanFactory类initializeBean方法源码如下

    	protected Object initializeBean(String beanName, Object bean, @Nullable RootBeanDefinition mbd) {
		//阶段1 处理aware方法
		if (System.getSecurityManager() != null) {
			AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
				invokeAwareMethods(beanName, bean);
				return null;
			}, getAccessControlContext());
		}
		else {
			invokeAwareMethods(beanName, bean);
		}
		//阶段2 applyBeanPostProcessorsBeforeInitialization
		Object wrappedBean = bean;
		if (mbd == null || !mbd.isSynthetic()) {
			wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);
		}
		//invokeInitMethods
		try {
			invokeInitMethods(beanName, wrappedBean, mbd);
		}
		catch (Throwable ex) {
			throw new BeanCreationException(
					(mbd != null ? mbd.getResourceDescription() : null),
					beanName, "Invocation of init method failed", ex);
		}
		//applyBeanPostProcessorsAfterInitialization
		if (mbd == null || !mbd.isSynthetic()) {
			wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);
		}

		return wrappedBean;
	}

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    Bean Aware接口回调

    https://docs.spring.io/spring-framework/docs/current/reference/html/core.html#beans-factory-aware

    Aware原理

    initializeBean中关于invokeAwareMethods的调用

    		//阶段1 处理aware方法
		if (System.getSecurityManager() != null) {
			AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
				invokeAwareMethods(beanName, bean);
				return null;
			}, getAccessControlContext());
		}
		else {
			invokeAwareMethods(beanName, bean);
		}

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    aware翻译为：知道的；察觉的；了解的；关注的

    public interface Aware {}

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    虽然Aware接口什么方法都没有，但是它有非常多的实现类，org.springframework.beans.factory这个包下以Aware结尾的接口。核心代码 AbstractAutowireCapableBeanFactory 类

    	private void invokeAwareMethods(String beanName, Object bean) {
		//Aware
		if (bean instanceof Aware) {
		    //BeanNameAware
			if (bean instanceof BeanNameAware) {
				((BeanNameAware) bean).setBeanName(beanName);
			}
			//BeanClassLoaderAware
			if (bean instanceof BeanClassLoaderAware) {
				ClassLoader bcl = getBeanClassLoader();
				if (bcl != null) {
					((BeanClassLoaderAware) bean).setBeanClassLoader(bcl);
				}
			}
			//BeanFactoryAware
			if (bean instanceof BeanFactoryAware) {
				((BeanFactoryAware) bean).setBeanFactory(AbstractAutowireCapableBeanFactory.this);
			}
		}
	}

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    Aware案例

    public class AwareBean implements BeanNameAware, BeanClassLoaderAware, BeanFactoryAware {

    @Override
    public void setBeanName(String name) {
        System.out.println("setBeanName：" + name);
    }

    @Override
    public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
        System.out.println("setBeanFactory：" + beanFactory);
    }

    @Override
    public void setBeanClassLoader(ClassLoader classLoader) {
        System.out.println("setBeanClassLoader：" + classLoader);
    }

}

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    client

    public class Client {
    public static void main(String[] args) {
        DefaultListableBeanFactory factory = new DefaultListableBeanFactory();
        factory.registerBeanDefinition("awareBean",
                BeanDefinitionBuilder.genericBeanDefinition(AwareBean.class).getBeanDefinition());
        factory.getBean("awareBean");
    }
}

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    输出

    setBeanName：awareBean
setBeanClassLoader：sun.misc.Launcher$AppClassLoader@18b4aac2
setBeanFactory：org.springframework.beans.factory.support.DefaultListableBeanFactory@30c7da1e: defining beans [awareBean]; root of factory hierarchy

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    Bean初始化 （postProcessBeforeInitialization）

    原理

    initializeBean中关于applyBeanPostProcessorsBeforeInitialization的调用

    		Object wrappedBean = bean;
		if (mbd == null || !mbd.isSynthetic()) {
			wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);
		}

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    applyBeanPostProcessorsBeforeInitialization源码

    	@Override
	public Object applyBeanPostProcessorsBeforeInitialization(Object existingBean, String beanName)
			throws BeansException {

		Object result = existingBean;
		for (BeanPostProcessor processor : getBeanPostProcessors()) {
			//方法的核心
			Object current = processor.postProcessBeforeInitialization(result, beanName);
			if (current == null) {
				return result;
			}
			result = current;
		}
		return result;
	}

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    根据源码processor.postProcessBeforeInitialization这一行就是这个方法的核心。

    BeanPostProcessor接口中的postProcessBeforeInitialization默认实现

    	@Nullable
	default Object postProcessBeforeInitialization(Object bean, String beanName) 
	throws BeansException {
		return bean;
	}

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    post 和 Process 通常翻译为：后处理，后续处理
    Before 在。。之前
    Initialization 初始化
    所以这个方法的意思为在初始化之前进行的处理过程。

    这个接口有2个实现类，比较重要：
    ApplicationContextAwareProcessor 和 CommonAnnotationBeanPostProcessor

    	@Override
	@Nullable
	public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
		if (!(bean instanceof EnvironmentAware || bean instanceof EmbeddedValueResolverAware ||
				bean instanceof ResourceLoaderAware || bean instanceof ApplicationEventPublisherAware ||
				bean instanceof MessageSourceAware || bean instanceof ApplicationContextAware ||
				bean instanceof ApplicationStartupAware)) {
			return bean;
		}

		AccessControlContext acc = null;

		if (System.getSecurityManager() != null) {
			acc = this.applicationContext.getBeanFactory().getAccessControlContext();
		}

		if (acc != null) {
			AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
				invokeAwareInterfaces(bean);
				return null;
			}, acc);
		}
		else {
			invokeAwareInterfaces(bean);
		}

		return bean;
	}

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    案例

    Bean初始化（invokeInitMethods）

    源码来自initializeBean第三部分，翻译为调用初始化方法

    		//invokeInitMethods
		try {
			invokeInitMethods(beanName, wrappedBean, mbd);
		}
		catch (Throwable ex) {
			throw new BeanCreationException(
					(mbd != null ? mbd.getResourceDescription() : null),
					beanName, "Invocation of init method failed", ex);
		}

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    Give a bean a chance to react now all its properties are set, and a chance to know about its owning bean factory (this object). This means checking whether the bean implements InitializingBean or defines a custom init method, and invoking the necessary callback(s) if it does.

    invokeInitMethods源码，翻译为调用初始化方法。

    	protected void invokeInitMethods(String beanName, Object bean, @Nullable RootBeanDefinition mbd)
			throws Throwable {
		//bean是否实现InitializingBean接口
		boolean isInitializingBean = (bean instanceof InitializingBean);
		
		if (isInitializingBean && (mbd == null || !mbd.hasAnyExternallyManagedInitMethod("afterPropertiesSet"))) {
			//如果是trace级别
			if (logger.isTraceEnabled()) {
				logger.trace("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 {
				//调用afterPropertiesSet
				((InitializingBean) bean).afterPropertiesSet();
			}
		}

		if (mbd != null && bean.getClass() != NullBean.class) {
			String initMethodName = mbd.getInitMethodName();
			if (StringUtils.hasLength(initMethodName) &&
					!(isInitializingBean && "afterPropertiesSet".equals(initMethodName)) &&
					!mbd.hasAnyExternallyManagedInitMethod(initMethodName)) {
				//调用	invokeCustomInitMethod
				invokeCustomInitMethod(beanName, bean, mbd);
			}
		}
	}

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    主要作用就是调用 afterPropertiesSet和invokeCustomInitMethod

    afterPropertiesSet

    public interface InitializingBean {
	//在配置文件设置之后
	void afterPropertiesSet() throws Exception;
}

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    invokeCustomInitMethod

    	protected void invokeCustomInitMethod(String beanName, Object bean, RootBeanDefinition mbd)
			throws Throwable {

		String initMethodName = mbd.getInitMethodName();
		Assert.state(initMethodName != null, "No init method set");
		Method initMethod = (mbd.isNonPublicAccessAllowed() ?
				BeanUtils.findMethod(bean.getClass(), initMethodName) :
				ClassUtils.getMethodIfAvailable(bean.getClass(), initMethodName));

		if (initMethod == null) {
			if (mbd.isEnforceInitMethod()) {
				throw new BeanDefinitionValidationException("Could not find an init method named '" +
						initMethodName + "' on bean with name '" + beanName + "'");
			}
			else {
				if (logger.isTraceEnabled()) {
					logger.trace("No default init method named '" + initMethodName +
							"' found on bean with name '" + beanName + "'");
				}
				// Ignore non-existent default lifecycle methods.
				return;
			}
		}

		if (logger.isTraceEnabled()) {
			logger.trace("Invoking init method  '" + initMethodName + "' on bean with name '" + beanName + "'");
		}
		Method methodToInvoke = ClassUtils.getInterfaceMethodIfPossible(initMethod, bean.getClass());

		if (System.getSecurityManager() != null) {
			AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
				ReflectionUtils.makeAccessible(methodToInvoke);
				return null;
			});
			try {
				AccessController.doPrivileged((PrivilegedExceptionAction<Object>)
						() -> methodToInvoke.invoke(bean), getAccessControlContext());
			}
			catch (PrivilegedActionException pae) {
				InvocationTargetException ex = (InvocationTargetException) pae.getException();
				throw ex.getTargetException();
			}
		}
		else {
			try {
				ReflectionUtils.makeAccessible(methodToInvoke);
				methodToInvoke.invoke(bean);
			}
			catch (InvocationTargetException ex) {
				throw ex.getTargetException();
			}
		}
	}

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    Bean初始化后（postProcessAfterInitialization）

    源码来自initializeBean第四部分

    		if (mbd == null || !mbd.isSynthetic()) {
			wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);
		}

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    applyBeanPostProcessorsAfterInitialization方法分析

    	@Override
	public Object applyBeanPostProcessorsAfterInitialization(Object existingBean, String beanName)
			throws BeansException {
		//当前bean	
		Object result = existingBean;
		//循环使用BeanPostProcessor 来处理
		for (BeanPostProcessor processor : getBeanPostProcessors()) {
			//使用每个处理器的postProcessAfterInitialization方法处理
			Object current = processor.postProcessAfterInitialization(result, beanName);	
			//如果处理后为null直接返回
			if (current == null) {
				return result;
			}
			result = current;
		}
		//所有的处理器处理完之后返回对象
		return result;
	}

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    BeanPostProcessor接口postProcessAfterInitialization方法的默认实现

    	@Nullable
	default Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
		return bean;
	}

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    阶段9总结

    Bean初始化分为四个阶段，其中在初始化的前后分别有前后处理器处理。最前面是Aware接口的一些处理。

    We recommend that you do not use the InitializingBean interface, because it unnecessarily couples the code to Spring. Alternatively, we suggest using the @PostConstruct annotation or specifying a POJO initialization method.

    我们不推荐使用InitializingBean，这样会导致Spring耦合。推荐@PostConstruct。

    阶段10：所有单例bean初始化完成后阶段 （初始化后）

    SmartInitializingSingleton

    smart 轻量
    initializing 初始化
    singleton 单例

    Callback interface triggered at the end of the singleton pre-instantiation phase during BeanFactory bootstrap.

    at the end of the singleton pre-instantiation phase 在单例预实例化阶段之后，下面我们来一个案例

    public class Entity implements SmartInitializingSingleton {

    private static final Logger logger = LoggerFactory.getLogger(Entity.class);

    public Entity() {
        logger.info("entity is init ... ");
    }

    @Override
    public void afterSingletonsInstantiated() {
        logger.info("afterSingletonsInstantiated is callback");
    }
}

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    输出

    INFO com.example.lurenjia.spring.c22.jd11.Entity - entity is init ... 
INFO com.example.lurenjia.spring.c22.jd11.Entity - afterSingletonsInstantiated is callback

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    通过实现SmartInitializingSingleton 在初始化后执行

    DubboLoadBalancedRestTemplateAutoConfiguration 中的实践

    	@Override
	public void afterSingletonsInstantiated() {
		loadBalancerInterceptorBean = retryLoadBalancerInterceptor != null
				? retryLoadBalancerInterceptor : loadBalancerInterceptor;
	}

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    阶段11：Bean使用阶段

    使用阶段相信大家都会不再赘述。

    阶段12：Bean销毁阶段

    案例1 DisposableBean

    public class Entity13 implements DisposableBean {

    private static final Logger logger = LoggerFactory.getLogger(Entity13.class);

    public Entity13() {
        logger.info("Entity13 is init ... ");
    }

    @Override
    public void destroy() throws Exception {
        logger.info("Entity13 is destroy ... ");
    }
}

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    @Configuration
public class Config13 {
    @Bean
    Entity13 entity13() {
        return new Entity13();
    }
}

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    public class Client1 {
    public static void main(String[] args) {
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(Config13.class);
        Entity13 bean = context.getBean(Entity13.class);
        System.out.println(bean);
        context.getBeanFactory().destroyBean(bean);
    }
}

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    输出

    com.example.lurenjia.spring.c22.jd13.Entity13 - Entity13 is init ... 
com.example.lurenjia.spring.c22.jd13.Entity13@318ba8c8
com.example.lurenjia.spring.c22.jd13.Entity13 - Entity13 is destroy ... 

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    案例2 @PreDestroy

    public class Entity132 {

    private static final Logger logger = LoggerFactory.getLogger(Entity13.class);

    public Entity132() {
        logger.info("Entity132 is init ... ");
    }

    @PreDestroy
    public void destroy() {
        logger.info("Entity132 is destroy ... ");
    }
}

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    输出

     INFO com.example.lurenjia.spring.c22.jd13.Entity13 - Entity132 is destroy ... 

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    使用@PreDestroy标记销毁时调用的方法。

    案例3 DestructionAwareBeanPostProcessor

    public class MyDestructionAwareBeanPostProcessor implements DestructionAwareBeanPostProcessor {

    private static final Logger logger = LoggerFactory.getLogger(MyDestructionAwareBeanPostProcessor.class);

    @Override
    public void postProcessBeforeDestruction(Object bean, String beanName) throws BeansException {
        logger.info(beanName + "is destroy");
    }
}

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    public class Client2 {
    public static void main(String[] args) {
        DefaultListableBeanFactory factory = new DefaultListableBeanFactory();
        //注册BeanPostProcessor
        factory.addBeanPostProcessor(new MyDestructionAwareBeanPostProcessor());
        //向容器中注入3个单例bean
        factory.registerBeanDefinition("entity2",
                BeanDefinitionBuilder.genericBeanDefinition(Entity2.class)
                        .getBeanDefinition());

        factory.preInstantiateSingletons();
        factory.destroySingleton("entity2");
    }
}

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    输出

    INFO com.example.lurenjia.spring.c22.jd13.d2.Entity2 - Entity2 init ... 
INFO com.example.lurenjia.spring.c22.jd13.d2.MyDestructionAwareBeanPostProcessor - entity2is destroy

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    总结

    • 实现DisposableBean
    • @PreDestroy标记销毁方法
    • 针对BeanDefinition实现DestructionAwareBeanPostProcessor

    We recommend that you do not use the DisposableBean callback interface, because it unnecessarily couples the code to Spring.

    Spring官方建议不要使用DisposableBean接口，因为会和Spring进行耦合。

    Alternatively, we suggest using the @PreDestroy annotation or specifying a generic method that is supported by bean definitions.

    我们建议使用@PreDestroy或者指定bean定义支持的通用方法。

    重要的类和接口

    AbstractApplicationContext

    public abstract class AbstractApplicationContext extends DefaultResourceLoader
		implements ConfigurableApplicationContext {}

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    BeanDefinitionRegistry

    AutowiredAnnotationBeanPostProcessor

    CommonAnnotationBeanPostProcessor

    BeanDefinition

    在这里插入图片描述
    在这里插入图片描述

    综合案例

    Container Extension Points 容器扩展点

    https://docs.spring.io/spring-framework/docs/current/reference/html/core.html#beans-factory-extension

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  • 原文地址：https://blog.csdn.net/qq_37151886/article/details/127558477