代码目录结构
small-spring-step-02
└── src
├── main
│ └── java
│ └── cn.bugstack.springframework.beans
│ ├── factory
│ │ ├── factory
│ │ │ ├── BeanDefinition.java
│ │ │ └── SingletonBeanRegistry.java
│ │ ├── support
│ │ │ ├── AbstractAutowireCapableBeanFactory.java
│ │ │ ├── AbstractBeanFactory.java
│ │ │ ├── BeanDefinitionRegistry.java
│ │ │ ├── DefaultListableBeanFactory.java
│ │ │ └── DefaultSingletonBeanRegistry.java
│ │ └── BeanFactory.java
│ └── BeansException.java
└── test
└── java
└── cn.bugstack.springframework.test
├── bean
│ └── UserService.java
└── ApiTest.java
实现代码
BeansException异常类
public class BeansException extends RuntimeException {
public BeansException(String msg) {
super(msg);
}
public BeansException(String msg, Throwable cause) {
super(msg, cause);
}
}
BeanFactory工厂接口
public interface BeanFactory {
Object getBean(String name) throws BeansException;
}
Bean的定义类
@SuppressWarnings({"rawtypes"})
public class BeanDefinition {
private Class beanClass;
public BeanDefinition(Class beanClass) {
this.beanClass = beanClass;
}
public Class getBeanClass() {
return beanClass;
}
public void setBeanClass(Class beanClass) {
this.beanClass = beanClass;
}
}
单例注册接口定义和实现接口
public interface SingletonBeanRegistry {
Object getSingleton(String beanName);
}
bean工厂的基类
public abstract class AbstractBeanFactory extends DefaultSingletonBeanRegistry implements BeanFactory {
@Override
public Object getBean(String name) throws BeansException {
Object bean = getSingleton(name);
if (bean != null) {
return bean;
}
BeanDefinition beanDefinition = getBeanDefinition(name);
return createBean(name, beanDefinition);
}
protected abstract BeanDefinition getBeanDefinition(String beanName) throws BeansException;
protected abstract Object createBean(String beanName, BeanDefinition beanDefinition) throws BeansException;
}
bean自动装配工厂的基类
public abstract class AbstractAutowireCapableBeanFactory extends AbstractBeanFactory {
@Override
protected Object createBean(String beanName, BeanDefinition beanDefinition) throws BeansException {
Object bean;
try {
bean = beanDefinition.getBeanClass().getDeclaredConstructor().newInstance();
} catch (InstantiationException | IllegalAccessException | NoSuchMethodException | InvocationTargetException e) {
throw new BeansException("Instantiation of bean failed", e);
}
addSingleton(beanName, bean);
return bean;
}
}
注册bean的接口
public interface BeanDefinitionRegistry {
/**
* 向注册表中注册 BeanDefinition
*
* @param beanName
* @param beanDefinition
*/
void registerBeanDefinition(String beanName, BeanDefinition beanDefinition);
}
bean的注册类
public class DefaultSingletonBeanRegistry implements SingletonBeanRegistry {
private final Map<String, Object> singletonObjects = new HashMap<>();
@Override
public Object getSingleton(String beanName) {
return singletonObjects.get(beanName);
}
protected void addSingleton(String beanName, Object singletonObject) {
singletonObjects.put(beanName, singletonObject);
}
}
bean工厂的核心实现类
public class DefaultListableBeanFactory extends AbstractAutowireCapableBeanFactory implements BeanDefinitionRegistry {
private final Map<String, BeanDefinition> beanDefinitionMap = new HashMap<>();
@Override
public void registerBeanDefinition(String beanName, BeanDefinition beanDefinition) {
beanDefinitionMap.put(beanName, beanDefinition);
}
@Override
public BeanDefinition getBeanDefinition(String beanName) throws BeansException {
BeanDefinition beanDefinition = beanDefinitionMap.get(beanName);
if (beanDefinition == null) throw new BeansException("No bean named '" + beanName + "' is defined");
return beanDefinition;
}
}
测试代码
UserService
public class UserService {
public void queryUserInfo() {
System.out.println("查询用户信息");
}
}
ApiTest
public class ApiTest {
@Test
public void test_BeanFactory(){
// 1.初始化 BeanFactory
DefaultListableBeanFactory beanFactory = new DefaultListableBeanFactory();
// 2.注册 bean
BeanDefinition beanDefinition = new BeanDefinition(UserService.class);
beanFactory.registerBeanDefinition("userService", beanDefinition);
// 3.第一次获取 bean
UserService userService = (UserService) beanFactory.getBean("userService");
userService.queryUserInfo();
// 4.第二次获取 bean from Singleton
UserService userService_singleton = (UserService) beanFactory.getSingleton("userService");
userService_singleton.queryUserInfo();
}
}
两次调用queryUserInfo成功.
标签:Spring,BeansException,beanName,bean,笔记,Bean,beanDefinition,public,BeanDefinition From: https://www.cnblogs.com/haoqirui/p/16890037.html