循环依赖代码.zip

package com.xushu.circulardependencies.One; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.beans.factory.config.BeanDefinition; import org.springframework.beans.factory.support.RootBeanDefinition; import java.lang.reflect.Field; import java.util.LinkedHashMap; import java.util.Map; import java.util.concurrent.ConcurrentHashMap; /*** * @Author 徐庶 * @Slogan 致敬大师，致敬未来的你 */ public class XuShuApplicationContext {// spring implements BeanFactory { private Map<String, BeanDefinition> beanDefinitionMap = new LinkedHashMap<>(256); // 一级缓存 、单例池 private final Map<String, Object> singletonObjects = new ConcurrentHashMap<>(256); // 二级级缓存 多线程线程安全， 提高性能 。 private final Map<String, Object> ealySingletonObjects = new ConcurrentHashMap<>(256); // 三级缓存， 保证Bean创建规范 private final Map<String, ObjectFactory> factoriesSingletonObjects = new ConcurrentHashMap<>(256); public XuShuApplicationContext() throws Exception { // 加载ioc容器： 创建所有的bean refresh(); } // ioc容器加载 private void refresh() throws Exception { // 1.解析配置 注册BeanDefinition loadBeanDefinitions(); // 创建所有的bean finishBeanFactoryInitialization(); } // 创建所有的bean private void finishBeanFactoryInitialization() throws InstantiationException, IllegalAccessException { // 循环所有的beanDefinition for (String beanName : beanDefinitionMap.keySet()) { getBean(beanName); } // 一个个去调用getBean创建bean } // 创建和获取Bean public Object getBean(String beanName) throws InstantiationException, IllegalAccessException { // 1. 判断bean是否已经创建 Object beanInst=getSingleton(beanName); // 1.2 如果已经创建返回 if(beanInst!=null){ return beanInst; } synchronized(singletonObjects) { // 1. 判断bean是否已经创建 beanInst=getSingleton(beanName); // 1.2 如果已经创建返回 if(beanInst!=null){ return beanInst; } // 1.1 如果没有创建 创建 // 2. 实例化 BeanDefinition.BeanClass.newInstance() RootBeanDefinition rootBeanDefinition = (RootBeanDefinition) beanDefinitionMap.get(beanName); Class<?> beanClass = rootBeanDefinition.getBeanClass(); Object bean = beanClass.newInstance(); // 判断当前是不是循环依赖 factoriesSingletonObjects.put(beanName, () -> { JdkProxyBeanPostProcessor jdkProxyBeanPostProcessor = new JdkProxyBeanPostProcessor(); Object aopBean = jdkProxyBeanPostProcessor.getEarlyBeanReference(bean, beanName); return aopBean; }); // 3.属性注入 @Autowired Field[] declaredFields = beanClass.getDeclaredFields(); for (Field declaredField : declaredFields) { Autowired annotation = declaredField.getAnnotation(Autowired.class); if (annotation != null) { String name = declaredField.getName(); Object beanB = getBean(name); // 赋值 declaredField.setAccessible(true); declaredField.set(bean, beanB); } } // 4. 初始化 AOP 动态 // 5.放入一级缓存 singletonObjects.put(beanName, bean); ealySingletonObjects.remove(beanName); factoriesSingletonObjects.remove(beanName); return bean; } } // 判断bean是否存在 private Object getSingleton(String beanName) { if(singletonObjects.containsKey(beanName)){ return singletonObjects.get(beanName); } synchronized (singletonObjects) { // 如果二级有就说明当前是循环依赖 if (ealySingletonObjects.containsKey(beanName)) { return ealySingletonObjects.get(beanName); } if(factoriesSingletonObjects.containsKey(beanName)){ ObjectFactory objectFactory = factoriesSingletonObjects.get(beanName); Object beanAop = objectFactory.getObject(); ealySingletonObjects.put(beanName,beanAop); return beanAop; } } return null; } /** * * 根据配置信息创建BeanDefinition 会根据配置信息动态创建 */ private void loadBeanDefinitions() { // 创建A BeanDefinition RootBeanDefinition aBeanDefinition = new RootBeanDefinition(AService.class); // 创建B BeanDefinition RootBeanDefinition bBeanDefinition = new RootBeanDefinition(BService.class); beanDefinitionMap.put("aService", aBeanDefinition); beanDefinitionMap.put("bService", bBeanDefinition); } }