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);
}
}