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The spring component framework is used to setup a plugin based, micro-kernel, standalone application (today, we will support webapp in later releases) which is based on SpringFramework. It can help you decouple your application into several components clearly with zero invasion and keep your application consistent between develop time and runtime.

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/**
 * @author XiongJie, Date: 13-11-11
 */
package net.happyonroad.component.container.feature;

import net.happyonroad.component.container.support.ComponentInputStreamResource;
import net.happyonroad.component.core.Component;
import net.happyonroad.component.core.ComponentResource;
import net.happyonroad.component.core.Features;
import net.happyonroad.spring.ServiceApplicationContext;
import org.codehaus.plexus.classworlds.realm.ClassRealm;
import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.core.io.InputStreamResource;

import java.io.IOException;
import java.io.InputStream;

/** 加载服务组件 */
public class ServiceFeatureResolver extends SpringFeatureResolver {

    public ServiceFeatureResolver() {
        super(90);
    }

    @Override
    public String getName() {
        return Features.SERVICE_FEATURE;
    }

    @Override
    public boolean hasFeature(Component component) {
        return component.getResource().exists("META-INF/service.xml");
    }

    @Override
    public void resolve(Component component) throws IOException {
        logger.debug("Resolving {} {} feature", component, getName());
        //根据service.xml为其构建parent context
        ComponentResource resource = component.getResource();
        InputStream serviceStream = resource.getServiceStream();
        try {
            ClassRealm realm = resolveContext.getClassRealm(component.getId());
            InputStream applicationStream = resource.getApplicationStream();
            try {
                AbstractApplicationContext parentContext = combineDependedApplicationAsParentContext(component);
                AbstractApplicationContext serviceContext =
                        resolveServiceContext(component, realm, serviceStream, parentContext);
                // 父上下文Start之后，应该为子下文准备好所有要import的对象
                // 所以，父上下文的 service package对象，应该在start事件内将所有import的bean导入过来
                serviceContext.start();
                resolveContext.registerFeature(component, getName(), serviceContext);
                //如果component里面有application.xml，其稍后会自动解析，并予以start
                // 子上下文start之后，也就是其准备好了export服务
                //父上下文会听到子上下文的started事件，转发给Service Package
                // Service package判断其事件类型
                // 如果是started，则 export services
            } finally {
                applicationStream.close();
            }
        } finally {
            serviceStream.close();
        }
        //再根据 application.xml 为其构建 application context(with parent)
        //而将service暴露出去，在这里并不需要有什么实际的动作，暴露应该是在别人来引用时，可以通过隔离审查
    }


    protected AbstractApplicationContext resolveServiceContext(Component component,
                                                               ClassRealm realm,
                                                               InputStream serviceStream,
                                                               AbstractApplicationContext parent) {
        //  这里要根据Service的解析，尤其是 Import的解析情况，决定给予什么样的Resource Loader
        //    这个Resource Loader，很有可能是面向 整个world或者loader的loader
        //    主要要达成的目的是，能够通过某个中介，将服务export过来，并且import过去
        ServiceApplicationContext context = new ServiceApplicationContext(component, realm, parent);
        InputStreamResource resource = new ComponentInputStreamResource(component, serviceStream, "META-INF/service.xml");
        context.load(resource);
        registerServiceHelpers(component, context, realm);
        context.refresh();
        return context;
    }

}