SpringContextUtil

/**
 *
 */
package gboat2.base.core.util;

import gboat2.base.bridge.exception.DefaultGboatNestedException;

import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

import org.osgi.framework.Bundle;
import org.osgi.framework.BundleEvent;
import org.osgi.framework.BundleListener;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.support.AbstractRefreshableApplicationContext;
import org.springframework.osgi.context.support.AbstractDelegatedExecutionApplicationContext;
import org.springframework.osgi.context.support.OsgiBundleXmlApplicationContext;

/**
 * Spring的Context操作辅助类
 * 在spring的xml中如下配置：
 * <bean class="gboat2.base.core.util.SpringContextUtil" factory-method="getInstance"/>
 *
 * @author lysming
 */
// FIXME hemw  研究一下为什么将 servletContexts 由 List 改为 Map 后平台无法启动
public final class SpringContextUtil implements ApplicationContextAware, BundleListener {

	private static Logger logger = LoggerFactory.getLogger(SpringContextUtil.class);

	private static SpringContextUtil context;

	private SpringContextUtil() {
	}

	public synchronized static SpringContextUtil getInstance() {
		if (context == null) {
			context = new SpringContextUtil();
		}
		return context;
	}

	private static final List<OsgiBundleXmlApplicationContext> servletContexts = Collections
			.synchronizedList(new LinkedList<OsgiBundleXmlApplicationContext>());

	public final void setApplicationContext(ApplicationContext context) {
		synchronized (servletContexts) {
			logger.debug("add " + context + " to SpringContextUtil");
			List<OsgiBundleXmlApplicationContext> toRemoved = new LinkedList<OsgiBundleXmlApplicationContext>();
			if (context instanceof OsgiBundleXmlApplicationContext) {
				//存在同名bundle的context，删除旧的
				OsgiBundleXmlApplicationContext bundleContext = (OsgiBundleXmlApplicationContext) context;
				for (OsgiBundleXmlApplicationContext ctx : servletContexts) {
					if (ctx.getBundle().getSymbolicName().equals(bundleContext.getBundle().getSymbolicName())) {
						logger.debug(bundleContext + " is already in SpringContextUtil");
						toRemoved.add(ctx);
					}
				}
				for (OsgiBundleXmlApplicationContext ctx : toRemoved) {
					logger.debug("remove " + ctx);
					servletContexts.remove(ctx);
				}
				servletContexts.add(bundleContext);
			}
		}
	}

	private OsgiBundleXmlApplicationContext getContextOfBundle(Bundle bundle) {
		synchronized (servletContexts) {
			for (OsgiBundleXmlApplicationContext context : servletContexts) {
				if (context.getBundle().getSymbolicName().equals(bundle.getSymbolicName())) {
					return context;
				}
			}
		}

		return null;
	}

    /**
     * 刷新 OSGI 环境中的 Spring 上下文
     * @param context
     * @return 如果 context 对应的 Bundle 的状态为 ACTIVE，且成功执行 refresh() 操作，则返回 true， 反之则返回 false
     */
    private boolean refreshApplicationContext(AbstractDelegatedExecutionApplicationContext context) {
        Bundle bundle = context.getBundle();
        if (bundle.getState() != Bundle.ACTIVE)
            return false;

        logger.debug("refresh Bundle [] 的 Spring ApplicationContext： {}", bundle.getSymbolicName(), context);
        context.refresh();
        return true;
    }

	/**
	 * 获取指定bundle内的beans
	 * @param className	类名称或接口名称
	 * @param bundle	查找的bundle
	 * @return 根据接口获得实现类
	 */
	public List<Object> getBeansOfType(Class<?> className, Bundle bundle) {
		logger.debug("try to find bean of " + className + " in " + bundle.getSymbolicName() + " ...");
		List<Object> beans = new LinkedList<Object>();
		OsgiBundleXmlApplicationContext context = getContextOfBundle(bundle);
		if (context != null) {
			Map<String, Object> map = new HashMap<String, Object>();
			try {
				@SuppressWarnings("unchecked")
				Map<String, Object> beansOfType = (Map<String, Object>)context.getBeansOfType(className);
				map = beansOfType;
			} catch (NoSuchBeanDefinitionException e) {
			} catch (IllegalStateException e) {
				if (context instanceof OsgiBundleXmlApplicationContext) {
					if (context.getBundle().getState() == Bundle.ACTIVE) {
						logger.debug("refresh " + context);
						context.refresh();
						try {
							@SuppressWarnings("unchecked")
							Map<String, Object> beansOfType = (Map<String, Object>)context.getBeansOfType(className);
							map = beansOfType;
						} catch (NoSuchBeanDefinitionException ignore) {
						}
					}
				}
			}
			if (!map.isEmpty()) {
				Iterator<String> it = map.keySet().iterator();
				String name;
				while (it.hasNext()) {
					name = it.next();
					beans.add(map.get(name));
				}
			}
		} else {
			throw new DefaultGboatNestedException("Can't find ApplicationContext for " + bundle.getSymbolicName());
		}
		logger.debug("find : " + beans);
		return beans;
	}

	public Object getBeanOfType(Class<?> className, Bundle bundle) {
		List<Object> objs = getBeansOfType(className, bundle);
		if(objs.size()==1){
			return objs.get(0);
		}else if(objs.size()>1){
			throw new DefaultGboatNestedException("more than one object of class["+className+"] in "+bundle.getSymbolicName());
		}else{
			return null;
		}
	}

	public Object getBeanOfId(String id) {
		logger.debug("try to find bean with id " + id);
		synchronized (servletContexts) {
			Object bean;
			for (ApplicationContext context : servletContexts) {
				try {
					bean = context.getBean(id);
					if (bean != null) {
						logger.debug("find : " + bean);
						return bean;
					}
				} catch (NoSuchBeanDefinitionException e) {
					continue;
				} catch (IllegalStateException e) {
					if (context instanceof OsgiBundleXmlApplicationContext) {
						if (((OsgiBundleXmlApplicationContext) context).getBundle().getState() == Bundle.ACTIVE) {
							logger.debug("refresh " + context);
							((AbstractRefreshableApplicationContext) context).refresh();
							try {
								bean = context.getBean(id);
								if (bean != null) {
									logger.debug("find : " + bean);
									return bean;
								}
							} catch (NoSuchBeanDefinitionException ignore) {
								continue;
							}
						}
					}
				}
			}
			return null;
		}
	}

	public Object getBeanOfId(String id, Bundle bundle) {
		logger.debug("try to find bean with id " + id + " in bundle[" + bundle.getSymbolicName() + "]");
		Object bean;
		OsgiBundleXmlApplicationContext context = getContextOfBundle(bundle);
		if (context != null) {
			try {
				bean = context.getBean(id);
				if (bean != null) {
					logger.debug("find : " + bean);
					return bean;
				}
			} catch (NoSuchBeanDefinitionException e) {
			} catch (IllegalStateException e) {
				if (context instanceof OsgiBundleXmlApplicationContext) {
					if (((OsgiBundleXmlApplicationContext) context).getBundle().getState() == Bundle.ACTIVE) {
						logger.debug("refresh " + context);
						((AbstractRefreshableApplicationContext) context).refresh();
						try {
							bean = context.getBean(id);
							if (bean != null) {
								logger.debug("find : " + bean);
								return bean;
							}
						} catch (NoSuchBeanDefinitionException ignore) {
						}
					}
				}
			}
		}
		return null;
	}

    public <T> T getBeanOfId(String id, Bundle bundle, Class<T> requiredType) {
        logger.debug("try to find bean with id " + id + " in bundle[" + bundle.getSymbolicName() + "]");
        T bean = null;
        OsgiBundleXmlApplicationContext context = getContextOfBundle(bundle);
        if (context == null)
            return null;

        try {
            bean = context.getBean(id, requiredType);
        } catch (IllegalStateException e) {
            if (refreshApplicationContext(context)) {
                bean = context.getBean(id, requiredType);
            }
        }
        return bean;
    }

	@Override
	public void bundleChanged(BundleEvent event) {
		if (event.getBundle().getState() == Bundle.RESOLVED) {
			OsgiBundleXmlApplicationContext bundleContext = getContextOfBundle(event.getBundle());
			if (bundleContext != null) {
				synchronized (servletContexts) {
					servletContexts.remove(bundleContext);
				}
			}
		}
	}
}