Spring 源码学习

1 public interface BeanFactory {    
2      
3      //对FactoryBean的转义定义，因为如果使用bean的名字是一个factoryBean那么返回就是一个factory          
5      String FACTORY_BEAN_PREFIX = "&"; 
6         
7      //根据bean的名字，获取在IOC容器中得到bean实例    
8      Object getBean(String name) throws BeansException;    
9    
10     //根据bean的名字和Class类型来得到bean实例，增加了类型安全验证机制。    
11      Object getBean(String name, Class requiredType) throws BeansException;    
12     
13     //提供对bean的检索，看看是否在IOC容器有这个名字的bean    
14      boolean containsBean(String name);    
15     
16     //根据bean名字得到bean实例，并同时判断这个bean是不是单例    
17     boolean isSingleton(String name) throws NoSuchBeanDefinitionException;    
18     
19     //得到bean实例的Class类型    
20     Class getType(String name) throws NoSuchBeanDefinitionException;    
21     
22     //得到bean的别名，如果根据别名检索，那么其原名也会被检索出来    
23    String[] getAliases(String name);    
24     
 }

package org.springframework.beans.factory.support;


/**
 * Default implementation of the
 * based on bean definition objects.
 *
 * <p>Can be used as a standalone bean factory, or as a superclass for custom
 * bean factories. Note that readers for specific bean definition formats are
 * typically implemented separately rather than as bean factory subclasses:.
 *
 */
@SuppressWarnings("serial")
public class DefaultListableBeanFactory extends AbstractAutowireCapableBeanFactory
		implements ConfigurableListableBeanFactory, BeanDefinitionRegistry, Serializable {

	private static Class<?> javaxInjectProviderClass = null;

	static {
		ClassLoader cl = DefaultListableBeanFactory.class.getClassLoader();
		try {
			javaxInjectProviderClass = cl.loadClass("javax.inject.Provider");
		}
		catch (ClassNotFoundException ex) {
			// JSR-330 API not available - Provider interface simply not supported then.
		}
	}


	/** Map from serialized id to factory instance */
	private static final Map<String, Reference<DefaultListableBeanFactory>> serializableFactories =
			new ConcurrentHashMap<String, Reference<DefaultListableBeanFactory>>(8);

	/** Optional id for this factory, for serialization purposes */
	private String serializationId;

        .
        .
        .


	/** Map of bean definition objects, keyed by bean name */
	private final Map<String, BeanDefinition> beanDefinitionMap = new ConcurrentHashMap<String, BeanDefinition>(64);

	/** Map of singleton and non-singleton bean names keyed by dependency type */
	private final Map<Class<?>, String[]> allBeanNamesByType = new ConcurrentHashMap<Class<?>, String[]>(64);

	/** Map of singleton-only bean names keyed by dependency type */
	private final Map<Class<?>, String[]> singletonBeanNamesByType = new ConcurrentHashMap<Class<?>, String[]>(64);

	/** List of bean definition names, in registration order */
	private final List<String> beanDefinitionNames = new ArrayList<String>();


	/**
	 * Create a new DefaultListableBeanFactory.
	 */
	public DefaultListableBeanFactory() {
		super();
	}

	/**
	 * Create a new DefaultListableBeanFactory with the given parent.
	 * @param parentBeanFactory the parent BeanFactory
	 */
	public DefaultListableBeanFactory(BeanFactory parentBeanFactory) {
		super(parentBeanFactory);
	}


	/**
	 * Set a custom autowire candidate resolver for this BeanFactory to use
	 * when deciding whether a bean definition should be considered as a
	 * candidate for autowiring.
	 */
	public void setAutowireCandidateResolver(final AutowireCandidateResolver autowireCandidateResolver) {
		Assert.notNull(autowireCandidateResolver, "AutowireCandidateResolver must not be null");
		if (autowireCandidateResolver instanceof BeanFactoryAware) {
			if (System.getSecurityManager() != null) {
				final BeanFactory target = this;
				AccessController.doPrivileged(new PrivilegedAction<Object>() {
					public Object run() {
						((BeanFactoryAware) autowireCandidateResolver).setBeanFactory(target);
						return null;
					}
				}, getAccessControlContext());
			}
			else {
				((BeanFactoryAware) autowireCandidateResolver).setBeanFactory(this);
			}
		}
		this.autowireCandidateResolver = autowireCandidateResolver;
	}

	/**
	 * Return the autowire candidate resolver for this BeanFactory (never {@code null}).
	 */
	public AutowireCandidateResolver getAutowireCandidateResolver() {
		return this.autowireCandidateResolver;
	}


	@Override
	public void copyConfigurationFrom(ConfigurableBeanFactory otherFactory) {
		super.copyConfigurationFrom(otherFactory);
		if (otherFactory instanceof DefaultListableBeanFactory) {
			DefaultListableBeanFactory otherListableFactory = (DefaultListableBeanFactory) otherFactory;
			this.allowBeanDefinitionOverriding = otherListableFactory.allowBeanDefinitionOverriding;
			this.allowEagerClassLoading = otherListableFactory.allowEagerClassLoading;
			this.autowireCandidateResolver = otherListableFactory.autowireCandidateResolver;
			this.resolvableDependencies.putAll(otherListableFactory.resolvableDependencies);
		}
	}


	//---------------------------------------------------------------------
	// Implementation of ListableBeanFactory interface
	//---------------------------------------------------------------------

	public <T> T getBean(Class<T> requiredType) throws BeansException {
		Assert.notNull(requiredType, "Required type must not be null");
		String[] beanNames = getBeanNamesForType(requiredType);
		if (beanNames.length > 1) {
			ArrayList<String> autowireCandidates = new ArrayList<String>();
			for (String beanName : beanNames) {
				if (getBeanDefinition(beanName).isAutowireCandidate()) {
					autowireCandidates.add(beanName);
				}
			}
			if (autowireCandidates.size() > 0) {
				beanNames = autowireCandidates.toArray(new String[autowireCandidates.size()]);
			}
		}
		if (beanNames.length == 1) {
			return getBean(beanNames[0], requiredType);
		}
		else if (beanNames.length > 1) {
			T primaryBean = null;
			for (String beanName : beanNames) {
				T beanInstance = getBean(beanName, requiredType);
				if (isPrimary(beanName, beanInstance)) {
					if (primaryBean != null) {
						throw new NoUniqueBeanDefinitionException(requiredType, beanNames.length,
								"more than one ‘primary‘ bean found of required type: " + Arrays.asList(beanNames));
					}
					primaryBean = beanInstance;
				}
			}
			if (primaryBean != null) {
				return primaryBean;
			}
			throw new NoUniqueBeanDefinitionException(requiredType, beanNames);
		}
		else if (getParentBeanFactory() != null) {
			return getParentBeanFactory().getBean(requiredType);
		}
		else {
			throw new NoSuchBeanDefinitionException(requiredType);
		}
	}

	@Override
	public boolean containsBeanDefinition(String beanName) {
		Assert.notNull(beanName, "Bean name must not be null");
		return this.beanDefinitionMap.containsKey(beanName);
	}

	public int getBeanDefinitionCount() {
		return this.beanDefinitionMap.size();
	}

	public String[] getBeanDefinitionNames() {
		synchronized (this.beanDefinitionMap) {
			if (this.frozenBeanDefinitionNames != null) {
				return this.frozenBeanDefinitionNames;
			}
			else {
				return StringUtils.toStringArray(this.beanDefinitionNames);
			}
		}
	}

	public String[] getBeanNamesForType(Class<?> type) {
		return getBeanNamesForType(type, true, true);
	}

	public String[] getBeanNamesForType(Class<?> type, boolean includeNonSingletons, boolean allowEagerInit) {
		if (!isConfigurationFrozen()  || type == null || !allowEagerInit) {
			return doGetBeanNamesForType(type, includeNonSingletons, allowEagerInit);
		}
		Map<Class<?>, String[]> cache =
				(includeNonSingletons ? this.allBeanNamesByType : this.singletonBeanNamesByType);
		String[] resolvedBeanNames = cache.get(type);
		if (resolvedBeanNames != null) {
			return resolvedBeanNames;
		}
		resolvedBeanNames = doGetBeanNamesForType(type, includeNonSingletons, allowEagerInit);
		cache.put(type, resolvedBeanNames);
		return resolvedBeanNames;
	}

	private String[] doGetBeanNamesForType(Class<?> type, boolean includeNonSingletons, boolean allowEagerInit) {
		List<String> result = new ArrayList<String>();

		// Check all bean definitions.
		String[] beanDefinitionNames = getBeanDefinitionNames();
		for (String beanName : beanDefinitionNames) {
			// Only consider bean as eligible if the bean name
			// is not defined as alias for some other bean.
			if (!isAlias(beanName)) {
				try {
					RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName);
					// Only check bean definition if it is complete.
					if (!mbd.isAbstract() && (allowEagerInit ||
							((mbd.hasBeanClass() || !mbd.isLazyInit() || this.allowEagerClassLoading)) &&
									!requiresEagerInitForType(mbd.getFactoryBeanName()))) {
						// In case of FactoryBean, match object created by FactoryBean.
						boolean isFactoryBean = isFactoryBean(beanName, mbd);
						boolean matchFound = (allowEagerInit || !isFactoryBean || containsSingleton(beanName)) &&
								(includeNonSingletons || isSingleton(beanName)) && isTypeMatch(beanName, type);
						if (!matchFound && isFactoryBean) {
							// In case of FactoryBean, try to match FactoryBean instance itself next.
							beanName = FACTORY_BEAN_PREFIX + beanName;
							matchFound = (includeNonSingletons || mbd.isSingleton()) && isTypeMatch(beanName, type);
						}
						if (matchFound) {
							result.add(beanName);
						}
					}
				}
				catch (CannotLoadBeanClassException ex) {
					if (allowEagerInit) {
						throw ex;
					}
					// Probably contains a placeholder: let‘s ignore it for type matching purposes.
					if (this.logger.isDebugEnabled()) {
						this.logger.debug("Ignoring bean class loading failure for bean ‘" + beanName + "‘", ex);
					}
					onSuppressedException(ex);
				}
				catch (BeanDefinitionStoreException ex) {
					if (allowEagerInit) {
						throw ex;
					}
					// Probably contains a placeholder: let‘s ignore it for type matching purposes.
					if (this.logger.isDebugEnabled()) {
						this.logger.debug("Ignoring unresolvable metadata in bean definition ‘" + beanName + "‘", ex);
					}
					onSuppressedException(ex);
				}
			}
		}
      .
      .
      .
      .
      .
	
}

private final Map<String, BeanDefinition> beanDefinitionMap = new ConcurrentHashMap<String, BeanDefinition>();

package com.springframework.beans.test;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.FileSystemXmlApplicationContext;

public class TestApplicationContext {

    public static void main(String[] args) {
        ApplicationContext applicationContext = new FileSystemXmlApplicationContext("classpath:beans.xml");
        System.out.println("numbers: " + applicationContext.getBeanDefinitionCount());
        ((Person)applicationContext.getBean("person")).work();
    }
}