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Add simple HelloWord example handling custom header
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‎examples/src/main/java/io/grpc/examples/header/CustomHeaderClient.java‎

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/*
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* Copyright 2015, Google Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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*
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following disclaimer
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* in the documentation and/or other materials provided with the
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* distribution.
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*
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* * Neither the name of Google Inc. nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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package io.grpc.examples.header;
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import io.grpc.Channel;
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import io.grpc.ChannelImpl;
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import io.grpc.ClientInterceptor;
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import io.grpc.ClientInterceptors;
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import io.grpc.examples.helloworld.GreeterGrpc;
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import io.grpc.examples.helloworld.HelloRequest;
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import io.grpc.examples.helloworld.HelloResponse;
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import io.grpc.transport.netty.NegotiationType;
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import io.grpc.transport.netty.NettyChannelBuilder;
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import java.util.concurrent.TimeUnit;
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import java.util.logging.Level;
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import java.util.logging.Logger;
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/**
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* A simple client that like {@link io.grpc.examples.helloworld.HelloWorldClient}.
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* This client can help you create custom headers.
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*/
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public class CustomHeaderClient {
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private static final Logger logger = Logger.getLogger(CustomHeaderClient.class.getName());
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private final ChannelImpl originChannel;
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private final GreeterGrpc.GreeterBlockingStub blockingStub;
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/**
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* A custom client.
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*/
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private CustomHeaderClient(String host, int port) {
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originChannel =
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NettyChannelBuilder.forAddress(host, port).negotiationType(NegotiationType.PLAINTEXT)
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.build();
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ClientInterceptor interceptor = new HeaderClientInterceptor();
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Channel channel = ClientInterceptors.intercept(originChannel, interceptor);
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blockingStub = GreeterGrpc.newBlockingStub(channel);
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}
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private void shutdown() throws InterruptedException {
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originChannel.shutdown().awaitTerminated(5, TimeUnit.SECONDS);
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}
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/**
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* A simple client method that like {@link io.grpc.examples.helloworld.HelloWorldClient}.
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*/
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private void greet(String name) {
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try {
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logger.info("Will try to greet " + name + " ...");
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HelloRequest request = HelloRequest.newBuilder().setName(name).build();
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HelloResponse response = blockingStub.sayHello(request);
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logger.info("Greeting: " + response.getMessage());
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} catch (RuntimeException e) {
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logger.log(Level.WARNING, "RPC failed", e);
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}
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}
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/**
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* Main start the client from the command line.
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*/
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public static void main(String[] args) throws Exception {
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CustomHeaderClient client = new CustomHeaderClient("localhost", 50051);
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try {
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/* Access a service running on the local machine on port 50051 */
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String user = "world";
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if (args.length > 0) {
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user = args[0]; /* Use the arg as the name to greet if provided */
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}
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client.greet(user);
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} finally {
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client.shutdown();
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}
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}
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}

‎examples/src/main/java/io/grpc/examples/header/CustomHeaderServer.java‎

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/*
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* Copyright 2015, Google Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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*
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following disclaimer
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* in the documentation and/or other materials provided with the
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* distribution.
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*
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* * Neither the name of Google Inc. nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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package io.grpc.examples.header;
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import io.grpc.ServerImpl;
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import io.grpc.ServerInterceptors;
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import io.grpc.examples.helloworld.GreeterGrpc;
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import io.grpc.examples.helloworld.HelloRequest;
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import io.grpc.examples.helloworld.HelloResponse;
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import io.grpc.stub.StreamObserver;
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import io.grpc.transport.netty.NettyServerBuilder;
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import java.util.logging.Logger;
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/**
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* A simple server that like {@link io.grpc.examples.helloworld.HelloWorldServer}.
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* You can get and response any header in {@link io.grpc.examples.header.HeaderServerInterceptor}.
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*/
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public class CustomHeaderServer {
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private static final Logger logger = Logger.getLogger(CustomHeaderServer.class.getName());
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/* The port on which the server should run */
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private static final int port = 50051;
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private ServerImpl server;
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private void start() throws Exception {
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server = NettyServerBuilder.forPort(port).addService(ServerInterceptors
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.intercept(GreeterGrpc.bindService(new GreeterImpl()), new HeaderServerInterceptor()))
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.build().start();
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logger.info("Server started, listening on " + port);
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Runtime.getRuntime().addShutdownHook(new Thread() {
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@Override
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public void run() {
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// Use stderr here since the logger may have been reset by its JVM shutdown hook.
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System.err.println("*** shutting down gRPC server since JVM is shutting down");
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CustomHeaderServer.this.stop();
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System.err.println("*** server shut down");
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}
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});
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}
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private void stop() {
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if (server != null) {
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server.shutdown();
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}
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}
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/**
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* Main launches the server from the command line.
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*/
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public static void main(String[] args) throws Exception {
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final CustomHeaderServer server = new CustomHeaderServer();
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server.start();
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}
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private class GreeterImpl implements GreeterGrpc.Greeter {
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@Override
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public void sayHello(HelloRequest req, StreamObserver<HelloResponse> responseObserver) {
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HelloResponse reply = HelloResponse.newBuilder().setMessage("Hello " + req.getName()).build();
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responseObserver.onValue(reply);
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responseObserver.onCompleted();
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}
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}
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}

‎examples/src/main/java/io/grpc/examples/header/HeaderClientInterceptor.java‎

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/*
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* Copyright 2015, Google Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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*
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
10+
* * Redistributions in binary form must reproduce the above
11+
* copyright notice, this list of conditions and the following disclaimer
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* in the documentation and/or other materials provided with the
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* distribution.
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*
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* * Neither the name of Google Inc. nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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package io.grpc.examples.header;
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import io.grpc.Call;
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import io.grpc.Channel;
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import io.grpc.ClientInterceptor;
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import io.grpc.ClientInterceptors;
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import io.grpc.Metadata;
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import io.grpc.MethodDescriptor;
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import java.util.logging.Logger;
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/**
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* A interceptor to handle client header.
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*/
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public class HeaderClientInterceptor implements ClientInterceptor {
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private static final Logger logger = Logger.getLogger(HeaderClientInterceptor.class.getName());
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private static Metadata.Key<String> customHeadKey =
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Metadata.Key.of("custom_client_header_key", Metadata.ASCII_STRING_MARSHALLER);
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@Override
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public <ReqT, RespT> Call<ReqT, RespT> interceptCall(MethodDescriptor<ReqT, RespT> method,
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Channel next) {
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return new ClientInterceptors.ForwardingCall<ReqT, RespT>(next.newCall(method)) {
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@Override
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public void start(Listener<RespT> responseListener, Metadata.Headers headers) {
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/* put custom header */
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headers.put(customHeadKey, "customRequestValue");
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super.start(new ClientInterceptors.ForwardingListener<RespT>(responseListener) {
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@Override
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public void onHeaders(Metadata.Headers headers) {
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/**
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* if you don't need receive header from server,
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* you can use {@link io.grpc.stub.MetadataUtils attachHeaders}
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* directly to send header
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*/
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logger.info("header received from server:" + headers.toString());
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super.onHeaders(headers);
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}
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}, headers);
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}
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};
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}
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}

‎examples/src/main/java/io/grpc/examples/header/HeaderServerInterceptor.java‎

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/*
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* Copyright 2015, Google Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
5+
* modification, are permitted provided that the following conditions are
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* met:
7+
*
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* * Redistributions of source code must retain the above copyright
9+
* notice, this list of conditions and the following disclaimer.
10+
* * Redistributions in binary form must reproduce the above
11+
* copyright notice, this list of conditions and the following disclaimer
12+
* in the documentation and/or other materials provided with the
13+
* distribution.
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*
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* * Neither the name of Google Inc. nor the names of its
16+
* contributors may be used to endorse or promote products derived from
17+
* this software without specific prior written permission.
18+
*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20+
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21+
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
22+
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
24+
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
25+
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26+
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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package io.grpc.examples.header;
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import io.grpc.Metadata;
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import io.grpc.ServerCall;
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import io.grpc.ServerCallHandler;
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import io.grpc.ServerInterceptor;
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import io.grpc.ServerInterceptors;
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import io.grpc.Status;
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import java.util.logging.Logger;
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/**
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* A interceptor to handle server header.
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*/
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public class HeaderServerInterceptor implements ServerInterceptor {
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private static final Logger logger = Logger.getLogger(HeaderServerInterceptor.class.getName());
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private static Metadata.Key<String> customHeadKey =
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Metadata.Key.of("custom_server_header_key", Metadata.ASCII_STRING_MARSHALLER);
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@Override
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public <ReqT, RespT> ServerCall.Listener<ReqT> interceptCall(
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String method,
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ServerCall<RespT> call,
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final Metadata.Headers requestHeaders,
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ServerCallHandler<ReqT, RespT> next) {
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logger.info("header received from client:" + requestHeaders.toString());
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return next.startCall(method, new ServerInterceptors.ForwardingServerCall<RespT>(call) {
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boolean sentHeaders = false;
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@Override
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public void sendHeaders(Metadata.Headers responseHeaders) {
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responseHeaders.put(customHeadKey, "customRespondValue");
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super.sendHeaders(responseHeaders);
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sentHeaders = true;
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}
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@Override
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public void sendPayload(RespT payload) {
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if (!sentHeaders) {
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sendHeaders(new Metadata.Headers());
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}
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super.sendPayload(payload);
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}
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@Override
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public void close(Status status, Metadata.Trailers trailers) {
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super.close(status, trailers);
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}
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}, requestHeaders);
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}
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}

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