需要先安装protoc（Protocol Buffers Compiler），可据此Protobuf Compiler Installation[1]下载
第一步：创建项目
创建两个新的Rust项目，分别作为服务端与客户端：

cargo new rust_grpc_server
cargo new rust_grpc_client

分别在项目根目录创建proto文件夹，并在其中创建一个叫hello.proto的文件

第二步：编写.proto文件
在proto/hello.proto文件中分别写入以下内容：

syntax = "proto3";
package hello;
// The greeting service definition.
service Greeter {
  // Sends a greeting
  rpc SayHello (HelloRequest) returns (HelloReply) {}
}

// The request message containing the user's name.
message HelloRequest {
  string name = 1;
}

// The response message containing the greetings.
message HelloReply {
  string message = 1;
}

第三步：添加依赖
在server的项目的Cargo.toml文件中添加以下依赖：

[dependencies]
tonic = "0.6"
tokio = { version = "1", features = ["full"] }
prost = "0.9"

[build-dependencies]
tonic-build = "0.6"

在client的项目的Cargo.toml文件中添加以下依赖：

[dependencies]
tonic = "0.6"
tokio = { version = "1", features = ["full"] }
prost = "0.9"
rand = "0.8"

[build-dependencies]
tonic-build = "0.6"

第四步：创建build脚本
分别在根目录创建一个build.rs文件，添加以下代码, 根据.proto文件生成相应的Rust代码：

fn main() {
    tonic_build::compile_protos("proto/hello.proto")
        .expect("Failed to compile proto files");
}

最终生成的代码类似

第五步：编写gRPC服务器
在server项目的src/main.rs中，创建一个gRPC服务器：

use std::time::SystemTime;
use tonic::{transport::Server, Request, Response, Status};

pub mod hello {
    tonic::include_proto!("hello");
}

use hello::greeter_server::{Greeter, GreeterServer};
use hello::{HelloReply, HelloRequest};

#[derive(Default)]
pub struct MyGreeter {}

#[tonic::async_trait]
impl Greeter for MyGreeter {
    async fn say_hello(
        &self,
        request: Request<HelloRequest>,
    ) -> Result<Response<HelloReply>, Status> {
        let reply = hello::HelloReply {
            message: format!(
                "Hello {}!,Current Time is {:?}",
                request.into_inner().name,
                SystemTime::now()
            ),
        };

        Ok(Response::new(reply))
    }
}

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let addr = "[::1]:50051".parse()?;
    let greeter = MyGreeter::default();

    println!("GreeterServer listening on {}", addr);

    Server::builder()
        .add_service(GreeterServer::new(greeter))
        .serve(addr)
        .await?;

    Ok(())
}

第六步：编写gRPC客户端
在client项目的src/main.rs文件中，添加一个客户端来测试服务器：

use rand::Rng;

pub mod hello {
    tonic::include_proto!("hello");
}

use hello::HelloRequest;

#[derive(Default)]
pub struct MyGreeter {}

// 客户端代码
#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
     // 堆代码 duidaima.com
    // 客户端测试
    let mut client = hello::greeter_client::GreeterClient::connect("http://[::1]:50051").await?;
    // 随机选择一个字符串出来
    let names = ["张三", "李四", "王五"];

    let mut rng = rand::thread_rng();

    let random_name = names[rng.gen_range(0..names.len())];

    let request = tonic::Request::new(HelloRequest {
        name: random_name.into(),
    });

    let response = client.say_hello(request).await?;

    println!("RESPONSE={:?}", response.into_inner().message);

    Ok(())
}

编译和运行
1.在server项目根目录执行cargo run来编译和运行项目，服务器将启动并监听在[::1]:50051

2.在client项目根目录执行cargo run来编译和运行项目，客户端将发送一个请求并打印出服务端的响应内容

参考资料
[1]Protobuf Compiler Installation: https://github.com/protocolbuffers/protobuf