EchoService

dubbo为consumer端的代理对象实现了EchoService接口。

使用示例：

<dubbo:reference id="hello" interface="com.zhang.HelloService" check="false" />

EchoService echoService = (EchoService) appCtx.getBean("hello");
Object str = echoService.$echo("zhang");

原理：

public interface EchoService {
    Object $echo(Object message);
}

//AbstractProxyFactory
public <T> T getProxy(Invoker<T> invoker) throws RpcException {
    Class<?>[] interfaces = null;
    String config = invoker.getUrl().getParameter("interfaces");
    if (config != null && config.length() > 0) {
        String[] types = Constants.COMMA_SPLIT_PATTERN.split(config);
        if (types != null && types.length > 0) {
            interfaces = new Class<?>[types.length + 2];
            interfaces[0] = invoker.getInterface();
            interfaces[1] = EchoService.class;
            for (int i = 0; i < types.length; i ++) {
                interfaces[i + 1] = ReflectUtils.forName(types[i]);
            }
        }
    }
    if (interfaces == null) {
        //加入了EchoService接口
        interfaces = new Class<?>[] {invoker.getInterface(), EchoService.class};
    }
    //JavassistProxyFactory和JdkProxyFactory分别实现EchoService接口
    return getProxy(invoker, interfaces);
}

provider在EchoFilter中处理$echo请求：

@Activate(group = Constants.PROVIDER, order = -110000)
public class EchoFilter implements Filter {
    public Result invoke(Invoker<?> invoker, Invocation inv) throws RpcException {
        if(inv.getMethodName().equals(Constants.$ECHO) 
　　　　　　　　&& inv.getArguments() != null && inv.getArguments().length == 1)
            return new RpcResult(inv.getArguments()[0]);
        return invoker.invoke(inv);
    }
}