在RPC框架中，Handler用于接收RpcRequest，经过处理后返回RpcResponse
@Slf4j
public class RpcRequestHandler {
private final ServiceProvider serviceProvider;
//获取一个单例模式的服务提供类
public RpcRequestHandler() {
serviceProvider = SingletonFactory.getInstance(ZkServiceProviderImpl.class);
}
/**
* Processing rpcRequest: call the corresponding method, and then return the method
*/
//从请求中提取方法名成，并调用到这个方法的服务
public Object handle(RpcRequest rpcRequest) {
Object service = serviceProvider.getService(rpcRequest.getRpcServiceName());
return invokeTargetMethod(rpcRequest, service);
}
/**
* get method execution results
*
* @param rpcRequest client request
* @param service service object
* @return the result of the target method execution
*/
//通过服务名称调用方法并返回结果
private Object invokeTargetMethod(RpcRequest rpcRequest, Object service) {
Object result;
try {
Method method = service.getClass().getMethod(rpcRequest.getMethodName(), rpcRequest.getParamTypes());
result = method.invoke(service, rpcRequest.getParameters());
log.info("service:[{}] successful invoke method:[{}]", rpcRequest.getInterfaceName(), rpcRequest.getMethodName());
} catch (NoSuchMethodException | IllegalArgumentException | InvocationTargetException | IllegalAccessException e) {
throw new RpcException(e.getMessage(), e);
}
return result;
}
}