Spring源码：BeanDefinitionRegistry 增删改查 Bean容器

蔚落 2023-05-28 05:04 7阅读 0赞

# 1、概述 #

BeanDefinitionRegistry 看名字就知道是 Bean的注册类，负责 Bean的注册、删除、获取等功能。

package org.springframework.beans.factory.support;
    
    import org.springframework.beans.factory.BeanDefinitionStoreException;
    import org.springframework.beans.factory.NoSuchBeanDefinitionException;
    import org.springframework.beans.factory.config.BeanDefinition;
    import org.springframework.core.AliasRegistry;
    
    public interface BeanDefinitionRegistry extends AliasRegistry {
    // 注册 Bean 到Spring容器
        void registerBeanDefinition(String var1, BeanDefinition var2) throws BeanDefinitionStoreException;
    // 从Spring容器中移除 Bean
        void removeBeanDefinition(String var1) throws NoSuchBeanDefinitionException;
    // 从Spring容器中获取 Bean
        BeanDefinition getBeanDefinition(String var1) throws NoSuchBeanDefinitionException;
    // 判断Spring容器中是否包含此 Bean
        boolean containsBeanDefinition(String var1);
    // 获取Spring容器中 Bean的name
        String[] getBeanDefinitionNames();
    // 获取Spring容器中 Bean的数量
        int getBeanDefinitionCount();
    
        boolean isBeanNameInUse(String var1);
    }

DefaultListableBeanFactory 实现了 BeanDefinitionRegistry 接口方法如下

package org.springframework.beans.factory.support;
    
    public class DefaultListableBeanFactory extends AbstractAutowireCapableBeanFactory implements ConfigurableListableBeanFactory, BeanDefinitionRegistry, Serializable {
    // 核心：这就是容器，Bean放在这里
        private final Map<String, BeanDefinition> beanDefinitionMap = new ConcurrentHashMap(256);
    // bean 的 name 集合
        private volatile List<String> beanDefinitionNames = new ArrayList(256);
        private volatile Set<String> manualSingletonNames = new LinkedHashSet(16);
            @Nullable
        private volatile String[] frozenBeanDefinitionNames;
    
        // 实现了 注册 Bean 到 Spring容器中
        public void registerBeanDefinition(String beanName, BeanDefinition beanDefinition) throws BeanDefinitionStoreException {
            Assert.hasText(beanName, "Bean name must not be empty");
            Assert.notNull(beanDefinition, "BeanDefinition must not be null");
            if (beanDefinition instanceof AbstractBeanDefinition) {
                try {
                    ((AbstractBeanDefinition)beanDefinition).validate();
                } catch (BeanDefinitionValidationException var9) {
                    throw new BeanDefinitionStoreException(beanDefinition.getResourceDescription(), beanName, "Validation of bean definition failed", var9);
                }
            }
    
            BeanDefinition oldBeanDefinition = (BeanDefinition)this.beanDefinitionMap.get(beanName);
            if (oldBeanDefinition != null) {
                if (!this.isAllowBeanDefinitionOverriding()) {
                    throw new BeanDefinitionStoreException(beanDefinition.getResourceDescription(), beanName, "Cannot register bean definition [" + beanDefinition + "] for bean '" + beanName + "': There is already [" + oldBeanDefinition + "] bound.");
                }
    
                if (oldBeanDefinition.getRole() < beanDefinition.getRole()) {
                    if (this.logger.isWarnEnabled()) {
                        this.logger.warn("Overriding user-defined bean definition for bean '" + beanName + "' with a framework-generated bean definition: replacing [" + oldBeanDefinition + "] with [" + beanDefinition + "]");
                    }
                } else if (!beanDefinition.equals(oldBeanDefinition)) {
                    if (this.logger.isInfoEnabled()) {
                        this.logger.info("Overriding bean definition for bean '" + beanName + "' with a different definition: replacing [" + oldBeanDefinition + "] with [" + beanDefinition + "]");
                    }
                } else if (this.logger.isDebugEnabled()) {
                    this.logger.debug("Overriding bean definition for bean '" + beanName + "' with an equivalent definition: replacing [" + oldBeanDefinition + "] with [" + beanDefinition + "]");
                }
    
                this.beanDefinitionMap.put(beanName, beanDefinition);
            } else {
                if (this.hasBeanCreationStarted()) {
                    Map var4 = this.beanDefinitionMap;
                    synchronized(this.beanDefinitionMap) {
                        this.beanDefinitionMap.put(beanName, beanDefinition);
                        List<String> updatedDefinitions = new ArrayList(this.beanDefinitionNames.size() + 1);
                        updatedDefinitions.addAll(this.beanDefinitionNames);
                        updatedDefinitions.add(beanName);
                        this.beanDefinitionNames = updatedDefinitions;
                        if (this.manualSingletonNames.contains(beanName)) {
                            Set<String> updatedSingletons = new LinkedHashSet(this.manualSingletonNames);
                            updatedSingletons.remove(beanName);
                            this.manualSingletonNames = updatedSingletons;
                        }
                    }
                } else {
                    this.beanDefinitionMap.put(beanName, beanDefinition);
                    this.beanDefinitionNames.add(beanName);
                    this.manualSingletonNames.remove(beanName);
                }
    
                this.frozenBeanDefinitionNames = null;
            }
    
            if (oldBeanDefinition != null || this.containsSingleton(beanName)) {
                this.resetBeanDefinition(beanName);
            }
    
        }
    
    // 从 Spring容器中移除 Bean
        public void removeBeanDefinition(String beanName) throws NoSuchBeanDefinitionException {
            Assert.hasText(beanName, "'beanName' must not be empty");
            BeanDefinition bd = (BeanDefinition)this.beanDefinitionMap.remove(beanName);
            if (bd == null) {
                if (this.logger.isTraceEnabled()) {
                    this.logger.trace("No bean named '" + beanName + "' found in " + this);
                }
    
                throw new NoSuchBeanDefinitionException(beanName);
            } else {
                if (this.hasBeanCreationStarted()) {
                    Map var3 = this.beanDefinitionMap;
                    synchronized(this.beanDefinitionMap) {
                        List<String> updatedDefinitions = new ArrayList(this.beanDefinitionNames);
                        updatedDefinitions.remove(beanName);
                        this.beanDefinitionNames = updatedDefinitions;
                    }
                } else {
                    this.beanDefinitionNames.remove(beanName);
                }
    
                this.frozenBeanDefinitionNames = null;
                this.resetBeanDefinition(beanName);
            }
        }
    
    // 容器中 Bean 的数量
        public int getBeanDefinitionCount() {
            return this.beanDefinitionMap.size();
        }
    
    
        public String[] getBeanDefinitionNames() {
            String[] frozenNames = this.frozenBeanDefinitionNames;
            return frozenNames != null ? (String[])frozenNames.clone() : StringUtils.toStringArray(this.beanDefinitionNames);
        }
    
    
    // 从容器中获取 Bean
        public BeanDefinition getBeanDefinition(String beanName) throws NoSuchBeanDefinitionException {
            BeanDefinition bd = (BeanDefinition)this.beanDefinitionMap.get(beanName);
            if (bd == null) {
                if (this.logger.isTraceEnabled()) {
                    this.logger.trace("No bean named '" + beanName + "' found in " + this);
                }
    
                throw new NoSuchBeanDefinitionException(beanName);
            } else {
                return bd;
            }
        }
    
    
    // 容器中是否包含指定 bean
        public boolean containsBeanDefinition(String beanName) {
            Assert.notNull(beanName, "Bean name must not be null");
            return this.beanDefinitionMap.containsKey(beanName);
        }
    }

如上代码，DefaultListableBeanFactory 实现了 里面的大部分方法，增删改查 Bean 都有了。

还有一个 方法是在 AbstractBeanFactory 中实现的

public abstract class AbstractBeanFactory extends FactoryBeanRegistrySupport implements ConfigurableBeanFactory {
    
        public boolean isBeanNameInUse(String beanName) {
    // SimpleAliasRegistry 中的 isAlias 方法 判断别名中是否用到，别名存储在private final Map<String, String> aliasMap = new ConcurrentHashMap<>(16);
    // 其他方法有兴趣的自己了解下
            return this.isAlias(beanName) || this.containsLocalBean(beanName) || this.hasDependentBean(beanName);
        }
    }