dubbo-rpc/dubbo-rpc-injvm/src/main/java/com/alibaba/dubbo/rpc/protocol/injvm/InjvmProtocol.java

/*
 * Copyright 1999-2011 Alibaba Group.
 *  
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *  
 *      http://www.apache.org/licenses/LICENSE-2.0
 *  
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.alibaba.dubbo.rpc.protocol.injvm;

import com.alibaba.dubbo.common.Constants;
import com.alibaba.dubbo.common.URL;
import com.alibaba.dubbo.common.extension.ExtensionLoader;
import com.alibaba.dubbo.rpc.Exporter;
import com.alibaba.dubbo.rpc.Invoker;
import com.alibaba.dubbo.rpc.Protocol;
import com.alibaba.dubbo.rpc.RpcException;
import com.alibaba.dubbo.rpc.protocol.AbstractProtocol;

/**
 * InjvmProtocol
 * 
 * @author qian.lei
 * @author william.liangf
 */
public class InjvmProtocol extends AbstractProtocol implements Protocol {
    
    public static final String NAME = Constants.LOCAL_PROTOCOL;

    public static final int DEFAULT_PORT = 0;

    public int getDefaultPort() {
        return DEFAULT_PORT;
    }
    
    private static InjvmProtocol INSTANCE;

    public InjvmProtocol() {
        INSTANCE = this;
    }
    
    public static InjvmProtocol getInjvmProtocol() {
        if (INSTANCE == null) {
            ExtensionLoader.getExtensionLoader(Protocol.class).getExtension(InjvmProtocol.NAME); // load
        }
        return INSTANCE;
    }

    public <T> Exporter<T> export(Invoker<T> invoker) throws RpcException {
        return new InjvmExporter<T>(invoker, invoker.getUrl().getServiceKey(), exporterMap);
    }

    public <T> Invoker<T> refer(Class<T> serviceType, URL url) throws RpcException {
        return new InjvmInvoker<T>(serviceType, url, url.getServiceKey(), exporterMap);
    }
    
    private boolean isExported(String key) {
        return exporterMap != null && exporterMap.containsKey(key);
    }
    
    public boolean isInjvmRefer(URL url) {
    	final boolean isJvmRefer;
    	String scope = url.getParameter(Constants.SCOPE_KEY);
    	//本身已经是jvm协议了，走正常流程就是了.
    	if (Constants.LOCAL_PROTOCOL.toString().equals(url.getProtocol())) {
    		isJvmRefer = false;
    	} else if (Constants.SCOPE_LOCAL.equals(scope) || (url.getParameter("injvm", false))) {
			//如果声明为本地引用
			//scope=local || injvm=true 等价 injvm标签未来废弃掉.
			isJvmRefer = true;	
		} else if (Constants.SCOPE_REMOTE.equals(scope)){
			//声明了是远程引用，则不做本地引用
			isJvmRefer = false;
		} else if (url.getParameter(Constants.GENERIC_KEY, false)){
			//泛化调用不走本地
			isJvmRefer = false;
		} else if (isExported(url.getServiceKey())) {
			//默认情况下如果本地有服务暴露，则引用本地服务.
			isJvmRefer = true;
		} else {
			isJvmRefer = false;
		}
		return isJvmRefer;
    }
}