import io.grpc.ForwardingServerCall.SimpleForwardingServerCall; //导入依赖的package包/类
/**
 * Echo the request headers from a client into response headers and trailers. Useful for
 * testing end-to-end metadata propagation.
 */
private static ServerInterceptor echoRequestHeadersInterceptor(final Metadata.Key<?>... keys) {
  final Set<Metadata.Key<?>> keySet = new HashSet<Metadata.Key<?>>(Arrays.asList(keys));
  return new ServerInterceptor() {
    @Override
    public <ReqT, RespT> ServerCall.Listener<ReqT> interceptCall(
        ServerCall<ReqT, RespT> call,
        final Metadata requestHeaders,
        ServerCallHandler<ReqT, RespT> next) {
      return next.startCall(new SimpleForwardingServerCall<ReqT, RespT>(call) {
            @Override
            public void sendHeaders(Metadata responseHeaders) {
              responseHeaders.merge(requestHeaders, keySet);
              super.sendHeaders(responseHeaders);
            }

            @Override
            public void close(Status status, Metadata trailers) {
              trailers.merge(requestHeaders, keySet);
              super.close(status, trailers);
            }
          }, requestHeaders);
    }
  };
}
 

import io.grpc.ForwardingServerCall.SimpleForwardingServerCall; //导入依赖的package包/类
/**
 * Intercept all GRPC calls
 * @param serverCall
 * @param metadata
 * @param serverCallHandler
 * @param <ReqT>
 * @param <RespT>
 * @return
 */
@Override
public <ReqT, RespT> ServerCall.Listener<ReqT> interceptCall(final ServerCall<ReqT, RespT> serverCall, Metadata metadata, ServerCallHandler<ReqT, RespT> serverCallHandler) {

    Timer.Context timer = metricRegistry.timer(metricName(M_REQ_TIME, serverCall.getMethodDescriptor().getFullMethodName().replace("/", "."))).time();
    Histogram histogram = metricRegistry.histogram(metricName(M_RESPONSE_SIZE, serverCall.getMethodDescriptor().getFullMethodName().replace("/", ".")));

    SimpleForwardingServerCall<ReqT, RespT> nextCall = new SimpleForwardingServerCall<ReqT, RespT>(serverCall) {
        @Override
        public void close(Status status, Metadata trailers) {
            Meter errorMeter = metricRegistry.meter(metricName(ERROR_METRIC, getMethodDescriptor().getFullMethodName().replace("/", ".")));
            if (!status.isOk()) {
                errorMeter.mark();
                log.error("An error occured with {}", serverCall.getMethodDescriptor());
            }

            timer.stop();

            super.close(status, trailers);
        }

        @Override
        public void sendMessage(RespT message) {
            super.sendMessage(message);

            if (message instanceof MessageLite) {
                histogram.update(((MessageLite) message).getSerializedSize());
                log.info("Message sent size = {}", ((MessageLite) message).getSerializedSize());
            }
        }

    };
    return serverCallHandler.startCall(nextCall, metadata);
}
 

import io.grpc.ForwardingServerCall.SimpleForwardingServerCall; //导入依赖的package包/类
@SuppressWarnings("checkstyle:MethodTypeParameterName")
@Override
public <ReqT, RespT> Listener<ReqT> interceptCall(
    final ServerCall<ReqT, RespT> call, final Metadata headers,
    final ServerCallHandler<ReqT, RespT> next) {
  TL.set(call);

  return next.startCall(new SimpleForwardingServerCall<ReqT, RespT>(call) {
    @Override
    public void close(final Status status, final Metadata trailers) {
      super.close(status, trailers);
      TL.remove();
    }

  }, headers);
}
 

import io.grpc.ForwardingServerCall.SimpleForwardingServerCall; //导入依赖的package包/类
/**
 * Echoes request headers with the specified key(s) from a client into response headers only.
 */
private static ServerInterceptor echoRequestMetadataInHeaders(final Metadata.Key<?>... keys) {
  final Set<Metadata.Key<?>> keySet = new HashSet<Metadata.Key<?>>(Arrays.asList(keys));
  return new ServerInterceptor() {
    @Override
    public <ReqT, RespT> ServerCall.Listener<ReqT> interceptCall(
        ServerCall<ReqT, RespT> call,
        final Metadata requestHeaders,
        ServerCallHandler<ReqT, RespT> next) {
      return next.startCall(new SimpleForwardingServerCall<ReqT, RespT>(call) {
        @Override
        public void sendHeaders(Metadata responseHeaders) {
          responseHeaders.merge(requestHeaders, keySet);
          super.sendHeaders(responseHeaders);
        }

        @Override
        public void close(Status status, Metadata trailers) {
          super.close(status, trailers);
        }
      }, requestHeaders);
    }
  };
}
 

import io.grpc.ForwardingServerCall.SimpleForwardingServerCall; //导入依赖的package包/类
/**
 * Echoes request headers with the specified key(s) from a client into response trailers only.
 */
private static ServerInterceptor echoRequestMetadataInTrailers(final Metadata.Key<?>... keys) {
  final Set<Metadata.Key<?>> keySet = new HashSet<Metadata.Key<?>>(Arrays.asList(keys));
  return new ServerInterceptor() {
    @Override
    public <ReqT, RespT> ServerCall.Listener<ReqT> interceptCall(
        ServerCall<ReqT, RespT> call,
        final Metadata requestHeaders,
        ServerCallHandler<ReqT, RespT> next) {
      return next.startCall(new SimpleForwardingServerCall<ReqT, RespT>(call) {
        @Override
        public void sendHeaders(Metadata responseHeaders) {
          super.sendHeaders(responseHeaders);
        }

        @Override
        public void close(Status status, Metadata trailers) {
          trailers.merge(requestHeaders, keySet);
          super.close(status, trailers);
        }
      }, requestHeaders);
    }
  };
}
 

import io.grpc.ForwardingServerCall.SimpleForwardingServerCall; //导入依赖的package包/类
@Override
public <ReqT, RespT> ServerCall.Listener<ReqT> interceptCall(
    MethodDescriptor<ReqT, RespT> method,
    ServerCall<RespT> call,
    final Metadata requestHeaders,
    ServerCallHandler<ReqT, RespT> next) {
  logger.info("header received from client:" + requestHeaders);
  return next.startCall(method, new SimpleForwardingServerCall<RespT>(call) {
    @Override
    public void sendHeaders(Metadata responseHeaders) {
      responseHeaders.put(customHeadKey, "customRespondValue");
      super.sendHeaders(responseHeaders);
    }
  }, requestHeaders);
}
 

import io.grpc.ForwardingServerCall.SimpleForwardingServerCall; //导入依赖的package包/类
@Override
public <ReqT, RespT> ServerCall.Listener<ReqT> interceptCall(
    ServerCall<ReqT, RespT> call,
    final Metadata requestHeaders,
    ServerCallHandler<ReqT, RespT> next) {
  logger.info("header received from client:" + requestHeaders);
  return next.startCall(new SimpleForwardingServerCall<ReqT, RespT>(call) {
    @Override
    public void sendHeaders(Metadata responseHeaders) {
      responseHeaders.put(CUSTOM_HEADER_KEY, "customRespondValue");
      super.sendHeaders(responseHeaders);
    }
  }, requestHeaders);
}