C++ 使用gRPC入门教程

忘是亡心i 2023-05-30 15:56 10阅读 0赞

gRPC是一个高性能、通用的开源RPC框架，其由Google主要面向移动应用开发并基于HTTP/2协议标准而设计，基于ProtoBuf(Protocol Buffers)序列化协议开发，且支持众多开发语言，能够基于语言自动生成客户端和服务端功能库。

### 1.新建工程GrpcClient、GrpcServer和GrpcLibrary ###

添加 - 新建项目 - 控制台应用 GrpcClient、GrpcServer。

添加 - 新建项目 - 类库 GrpcLibrary。 工程中的三个项目情况如下：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpeWF6aGVuMjAxMQ_size_16_color_FFFFFF_t_70][]

### 2.自定义服务 ###

在项目GrpcLibrary里添加HelloWorld.proto用以生成代码。

syntax = "proto3";
    package GrpcLibrary;
    
    service GrpcService {
      rpc SayHello (HelloRequest) returns (HelloReply) {}
    }
    
    message HelloRequest {
      string name = 1;
    }
    
    message HelloReply {
      string message = 1;
    }

执行命令

ThirdParty\grpc_build\bin\protoc.exe -IGrpcLibrary --cpp_out GrpcLibrary  GrpcLibrary\HelloWorld.proto --grpc_out GrpcLibrary --plugin=protoc-gen-grpc=ThirdParty\grpc_build\bin\grpc_cpp_plugin.exe

命令执行成功后，GrpcLibrary目录下会生成HelloWorld.grpc.pb.cc、HelloWorld.grpc.pb.h、HelloWorld.pb.cc和HelloWorld.pb.h

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpeWF6aGVuMjAxMQ_size_16_color_FFFFFF_t_70 1][]

将其都添加到项目GrpcLibrary中。最后GrpcClient、GrpcServer分别引用类库GrpcLibrary。

### 3.服务端 ###

// greeter_server.cc
    #include <iostream>
    #include <memory>
    #include <string>
    
    #include <grpcpp/grpcpp.h>
    
    #ifdef BAZEL_BUILD
    #include "examples/protos/helloworld.grpc.pb.h"
    #else
    #include "HelloWorld.grpc.pb.h"
    #endif
    
    using grpc::Server;
    using grpc::ServerBuilder;
    using grpc::ServerContext;
    using grpc::Status;
    using GrpcLibrary::HelloRequest;
    using GrpcLibrary::HelloReply;
    using GrpcLibrary::GrpcService;
    
    // Logic and data behind the server's behavior.
    class GreeterServiceImpl final : public GrpcService::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;
    
        ServerBuilder builder;
        // Listen on the given address without any authentication mechanism.
        builder.AddListeningPort(server_address, grpc::InsecureServerCredentials());
        // Register "service" as the instance through which we'll communicate with
        // clients. In this case it corresponds to an *synchronous* service.
        builder.RegisterService(&service);
        // Finally assemble the server.
        std::unique_ptr<Server> server(builder.BuildAndStart());
        std::cout << "Server listening on " << server_address << std::endl;
    
        // Wait for the server to shutdown. Note that some other thread must be
        // responsible for shutting down the server for this call to ever return.
        server->Wait();
    }
    
    int main(int argc, char** argv) {
        RunServer();
    
        return 0;
    }

### 4.客户端 ###

// greeter_client.cc
    #include <iostream>
    #include <memory>
    #include <string>
    
    #include <grpcpp/grpcpp.h>
    
    #ifdef BAZEL_BUILD
    #include "examples/protos/helloworld.grpc.pb.h"
    #else
    #include "helloworld.grpc.pb.h"
    #endif
    
    using grpc::Channel;
    using grpc::ClientContext;
    using grpc::Status;
    using GrpcLibrary::HelloRequest;
    using GrpcLibrary::HelloReply;
    using GrpcLibrary::GrpcService;
    
    class GreeterClient {
    public:
        GreeterClient(std::shared_ptr<Channel> channel)
            : stub_(GrpcService::NewStub(channel)) {}
    
    
        std::string SayHello(const std::string& user) {
            // Data we are sending to the server.
            HelloRequest request;
            request.set_name(user);
    
            // Container for the data we expect from the server.
            HelloReply reply;
    
            // Context for the client. It could be used to convey extra information to
            // the server and/or tweak certain RPC behaviors.
            ClientContext context;
    
            // The actual RPC.
            Status status = stub_->SayHello(&context, request, &reply);
    
            // Act upon its status.
            if (status.ok()) {
                return reply.message();
            }
            else {
                std::cout << status.error_code() << ": " << status.error_message()
                    << std::endl;
                return "RPC failed";
            }
        }
    
    private:
        std::unique_ptr<GrpcService::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;
    }

### 5.测试 ###

先启动服务的，再启动客户端。

![20191111110528651.png][]

![2019111111053487.png][]

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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpeWF6aGVuMjAxMQ_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/20191111110115229.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2xpeWF6aGVuMjAxMQ==,size_16,color_FFFFFF,t_70
[20191111110528651.png]: https://img-blog.csdnimg.cn/20191111110528651.png
[2019111111053487.png]: https://img-blog.csdnimg.cn/2019111111053487.png