Spring（3）-手动注册BeanDefinition
作者：互联网
大体思路：
1、选择BeanDefinition的实现类，并实例化BeanDefinition
2、注册BeanDefinition
3、获取Bean，看看是不是正常工作的。
非抽象的实现类主要有三个
1、GenericBeanDefinition，这个也是官方推荐使用的，注释里提到可以动态设置parent bean definition等。
2、RootBeanDefinition，这个跟@Configuration注解有关。
3、ChildBeanDefinition，这个也可以实现设置parent bean definition，不过它是预先定义parent/child关系，官方也不推荐使用了，看注释可以知道，从spring2.5开始
GenericBeanDefinition已经替代ChildBeanDefinition 了。
基于以上思路，我们选择GenericBeanDefinition
public class GenericBeanDefinition extends AbstractBeanDefinition {
@Nullable
private String parentName;
/**
* Create a new GenericBeanDefinition, to be configured through its bean
* properties and configuration methods.
* @see #setBeanClass
* @see #setScope
* @see #setConstructorArgumentValues
* @see #setPropertyValues
*/
public GenericBeanDefinition() {
super();
}
/**
* Create a new GenericBeanDefinition as deep copy of the given
* bean definition.
* @param original the original bean definition to copy from
*/
public GenericBeanDefinition(BeanDefinition original) {
super(original);
}
@Override
public void setParentName(@Nullable String parentName) {
this.parentName = parentName;
}
@Override
@Nullable
public String getParentName() {
return this.parentName;
}
@Override
public AbstractBeanDefinition cloneBeanDefinition() {
return new GenericBeanDefinition(this);
}
@Override
public boolean equals(@Nullable Object other) {
if (this == other) {
return true;
}
if (!(other instanceof GenericBeanDefinition)) {
return false;
}
GenericBeanDefinition that = (GenericBeanDefinition) other;
return (ObjectUtils.nullSafeEquals(this.parentName, that.parentName) && super.equals(other));
}
@Override
public String toString() {
if (this.parentName != null) {
return "Generic bean with parent '" + this.parentName + "': " + super.toString();
}
return "Generic bean: " + super.toString();
}
}
框架里面一般是怎么使用GenericBeanDefinition的呢？
一般是在BeanDefinitionBuilder里面，或者是BeanDefinitionReaderUtils，我记得是这个，由于这个笔记本不好用，简单搜下
然后就是注册BeanDefinition了
找一个beanFactory，
public class DefaultListableBeanFactory extends AbstractAutowireCapableBeanFactory
implements ConfigurableListableBeanFactory, BeanDefinitionRegistry, Serializable {
不只实现了ConfigurableListableBeanFactory，还实现了BeanDefinitionRegistry
public interface BeanDefinitionRegistry extends AliasRegistry {
/**
* Register a new bean definition with this registry.
* Must support RootBeanDefinition and ChildBeanDefinition.
* @param beanName the name of the bean instance to register
* @param beanDefinition definition of the bean instance to register
* @throws BeanDefinitionStoreException if the BeanDefinition is invalid
* @throws BeanDefinitionOverrideException if there is already a BeanDefinition
* for the specified bean name and we are not allowed to override it
* @see GenericBeanDefinition
* @see RootBeanDefinition
* @see ChildBeanDefinition
*/
void registerBeanDefinition(String beanName, BeanDefinition beanDefinition)
throws BeanDefinitionStoreException;
..........
}
所以，我们只要调用这个beanFactory的注册方法即可。
生成beanName
BeanNameGenerator接口，有两个实现类
public interface BeanNameGenerator {
/**
* Generate a bean name for the given bean definition.
* @param definition the bean definition to generate a name for
* @param registry the bean definition registry that the given definition
* is supposed to be registered with
* @return the generated bean name
*/
String generateBeanName(BeanDefinition definition, BeanDefinitionRegistry registry);
}
AnnatationBeanNameGenerator就是我们平时使用的注解方式@Autowired，的一个这样的格式，而默认的beanName则是，类名称+#+0（com.spring.learn.service.impl.TestServiceImpl#0）这样的。
bean之间的依赖
通过constructor，或者property方式注入
之前不是说过BeanDefinition接口里面有两个参数，一个是关于构造函数，一个是关于属性set方法注入的。
构造器注入代码
GenericBeanDefinition controllerBeanDefinition = (GenericBeanDefinition) BeanDefinitionBuilder.
genericBeanDefinition(TestControllerWithConstructor.class)
.addConstructorArgValue("controller name is TestController")
.addConstructorArgReference(testServiceName)
.getBeanDefinition();
属性值注入代码
GenericBeanDefinition propertyControllerBeanDefinition = (GenericBeanDefinition) BeanDefinitionBuilder
.genericBeanDefinition(TestControllerWithProperty.class)
.addPropertyValue("name","name is property controller")
.addPropertyReference("testService",testServiceName).getBeanDefinition();
完成注入代码：
public static void main(String[] args) {
// SpringApplication.run(SpringLearnApplication.class, args);
//创建一个工厂来
DefaultListableBeanFactory beanFactory = new DefaultListableBeanFactory();
//创建beanDefinition
GenericBeanDefinition beanDefinition = (GenericBeanDefinition) BeanDefinitionBuilder.genericBeanDefinition(TestServiceImpl.class)
.getBeanDefinition();
//创建beanDefinition Name
String testServiceName = AnnotationBeanNameGenerator.INSTANCE.generateBeanName(beanDefinition,beanFactory);
//注入到spring 工厂里
beanFactory.registerBeanDefinition(testServiceName,beanDefinition);
//创建controller，这个builder模式里边，要调用constructor的方法
GenericBeanDefinition controllerBeanDefinition = (GenericBeanDefinition) BeanDefinitionBuilder.
genericBeanDefinition(TestControllerWithConstructor.class)
.addConstructorArgValue("controller name is TestController")
.addConstructorArgReference(testServiceName)
.getBeanDefinition();
String controllerBeanName = AnnotationBeanNameGenerator.INSTANCE.generateBeanName(controllerBeanDefinition,beanFactory);
beanFactory.registerBeanDefinition(controllerBeanName,controllerBeanDefinition);
//---------------------------------------------
//注入之后，再取出来，将controller里面service和 spring里面的service作对比是不是一样的。
TestControllerWithConstructor testController = (TestControllerWithConstructor) beanFactory.getBean(controllerBeanName);
TestService testService = (TestService) beanFactory.getBean(testServiceName);
Assert.isTrue(testController.getTestService()==testService,"他们不相等，有问题");
//__________________________________________________
//这个是通过属性值property注入到DefaultListableBeanFactory
GenericBeanDefinition propertyControllerBeanDefinition = (GenericBeanDefinition) BeanDefinitionBuilder
.genericBeanDefinition(TestControllerWithProperty.class)
.addPropertyValue("name","name is property controller")
.addPropertyReference("testService",testServiceName).getBeanDefinition();
String propertyControllerName = AnnotationBeanNameGenerator.INSTANCE.generateBeanName(propertyControllerBeanDefinition,beanFactory);
beanFactory.registerBeanDefinition(propertyControllerName,propertyControllerBeanDefinition);
//注入进去之后，再取出propertyController
TestControllerWithProperty propertyController = (TestControllerWithProperty) beanFactory.getBean(propertyControllerName);
System.out.println(propertyController.getName());
Assert.isTrue(propertyController.getTestService()==testService,"他们不相等，有问题");
}
https://www.cnblogs.com/grey-wolf/p/12070377.html
今天就到这了，我去看别的了，
标签：definition,GenericBeanDefinition,name,beanFactory,Spring,手动,bean,public,BeanDefi 来源： https://www.cnblogs.com/fuckingPangzi/p/15738051.html