Spring获取所有管理的类和依赖

最新推荐文章于 2022-05-29 16:57:54 发布

oldbalck

最新推荐文章于 2022-05-29 16:57:54 发布

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文章标签： java python

原文链接：https://my.oschina.net/bughope/blog/818204

本文详细介绍了Spring容器中Bean的管理方式，包括如何通过Spring框架获取所有Bean的名称及其依赖关系，同时深入探讨了DefaultListableBeanFactory的作用及其实现。

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import java.util.Arrays;

import lombok.extern.log4j.Log4j;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.support.DefaultListableBeanFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.annotation.Lazy;
import org.springframework.stereotype.Component;
import org.springframework.web.context.support.XmlWebApplicationContext;


/**
 * 获取spring 容器的上下文
 * 
 * @author 
 * @date 2015年5月13日
 * @time 下午6:26:48
 */
@Component
@Lazy(false)
@Log4j
public class SpringApplicationContextUtil implements ApplicationContextAware {

	//private final Logger logger = LogManager.getLogger(getClass());
	
	private static XmlWebApplicationContext applicationContext;

	@Override
	public void setApplicationContext(ApplicationContext ac) throws BeansException {
		applicationContext = (XmlWebApplicationContext)ac;
		DefaultListableBeanFactory slbf = (DefaultListableBeanFactory) applicationContext.getBeanFactory();
		log.error("ac.getBeanDefinitionNames()");
		String [] arr = slbf.getBeanDefinitionNames();
		for(String s:arr){
			log.error(s);
			System.out.println(slbf.getBean(s).getClass());
			log.error(Arrays.asList(slbf.getDependentBeans(s)));
			log.error(Arrays.asList(slbf.getDependenciesForBean(s)));
			System.out.println("----------------------");
		}
	}

	public static ApplicationContext getApplicationContext() {
		return applicationContext;
	}

	public static Object getBean(String name) {
		return getApplicationContext().getBean(name);
	}

	public static <T> T getBean(Class<T> arg0) {
		return getApplicationContext().getBean(arg0);
	}

}

有个群友在群里问如何获取到一个容易内所有的bean

查了下源码,其实在

DefaultListableBeanFactory

/** 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;

	/** Whether to allow re-registration of a different definition with the same name */
	private boolean allowBeanDefinitionOverriding = true;

	/** Whether to allow eager class loading even for lazy-init beans */
	private boolean allowEagerClassLoading = true;

	/** Resolver to use for checking if a bean definition is an autowire candidate */
	private AutowireCandidateResolver autowireCandidateResolver = new SimpleAutowireCandidateResolver();

	/** Map from dependency type to corresponding autowired value */
	private final Map<Class<?>, Object> resolvableDependencies = new HashMap<Class<?>, Object>(16);

	/** 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>();

这里面都有,只是为了保护设置成为了私有的.

不过首先得了解spring的实例化过程

先通过xml配置或者注解解析spring管理的bean 的定义 BeanDefinition

例如依赖谁,是不是单利，是否延迟初始化等.这里就可以找到是否有循环依赖

然后再根据定义实力化bean，并反射设置依赖

转载于:https://my.oschina.net/bughope/blog/818204