使用C++写一个grpc的通信案例

好的，以下是一个简单的grpc通信案例。

首先，安装protobuf和grpc。在Ubuntu下，可以使用以下命令安装：

sudo apt-get install protobuf-compiler
sudo apt-get install libprotobuf-dev
sudo apt-get install grpc-tools
sudo apt-get install libgrpc-dev

接下来，我们需要定义.proto文件。例如，我们定义一个Hello.proto文件：

syntax = "proto3";

package helloworld;

message HelloRequest {
  string name = 1;
}

message HelloReply {
  string message = 1;
}

service Greeter {
  rpc SayHello (HelloRequest) returns (HelloReply) {}
}

然后，使用以下命令生成C++代码：

protoc -I=./ --grpc_out=./ --plugin=protoc-gen-grpc=`which grpc_cpp_plugin` ./Hello.proto
protoc -I=./ --cpp_out=./ ./Hello.proto

生成的代码包括Hello.pb.h和Hello.pb.cc，以及Hello.grpc.pb.h和Hello.grpc.pb.cc。

接下来，我们编写客户端代码：

#include <iostream>
#include <memory>
#include <string>
#include <grpcpp/grpcpp.h>
#include "Hello.grpc.pb.h"

using grpc::Channel;
using grpc::ClientContext;
using grpc::Status;
using helloworld::HelloRequest;
using helloworld::HelloReply;
using helloworld::Greeter;

class GreeterClient {
 public:
  GreeterClient(std::shared_ptr<Channel> channel)
      : stub_(Greeter::NewStub(channel)) {}

  std::string SayHello(const std::string& user) {
    HelloRequest request;
    request.set_name(user);

    HelloReply reply;
    ClientContext context;

    Status status = stub_->SayHello(&context, request, &reply);

    if (status.ok()) {
      return reply.message();
    } else {
      return "RPC failed";
    }
  }

 private:
  std::unique_ptr<Greeter::Stub> stub_;
};

int main(int argc, char** argv) {
  GreeterClient greeter(grpc::CreateChannel("localhost:50051", grpc::InsecureChannelCredentials()));
  std::string user("world");
  std::string reply = greeter.SayHello(user);
  std::cout << "Greeter received: " << reply << std::endl;

  return 0;
}

最后，编写服务器端代码：

#include <iostream>
#include <memory>
#include <string>
#include <grpcpp/grpcpp.h>
#include "Hello.grpc.pb.h"

using grpc::Server;
using grpc::ServerBuilder;
using grpc::ServerContext;
using grpc::Status;
using helloworld::HelloRequest;
using helloworld::HelloReply;
using helloworld::Greeter;

class GreeterServiceImpl final : public Greeter::Service {
  Status SayHello(ServerContext* context, const HelloRequest* request,
                  HelloReply* reply) override {
    std::string prefix("Hello ");
    reply->set_message(prefix + request->name());
    return Status::OK;
  }
};

void RunServer() {
  std::string server_address("0.0.0.0:50051");
  GreeterServiceImpl service;

  grpc::EnableDefaultHealthCheckService(true);
  grpc::reflection::InitProtoReflectionServerBuilderPlugin();
  ServerBuilder builder;
  builder.AddListeningPort(server_address, grpc::InsecureServerCredentials());
  builder.RegisterService(&service);
  std::unique_ptr<Server> server(builder.BuildAndStart());
  std::cout << "Server listening on " << server_address << std::endl;
  server->Wait();
}

int main(int argc, char** argv) {
  RunServer();
  return 0;
}

现在，我们可以先运行服务器端代码，然后再运行客户端代码，观察输出结果。