.netcore grpc服务端流方法详解

一、服务端流式处理概述

1. 客户端向服务端发送请求，服务端可以将多个消息流式传输回调用方
2. 和客户端流相反，客户端流发出请求，服务端可以传输一批消息给客户端，直至本次请求响应完全结束。
3. 针对文件分段传输下载，该方式非常有用。

二、案例介绍

1. 提供一个一元方法查询文件
2. 提供一个文件流传输的服务端流式方法，进行文件流推送

三、服务端配置（注意：grpc相关配置参考我之前的文章）

// 1.提供公共的实体proto文件
// 2.服务引用对应的proto文件
// 3.定义三个客户流方法syntax = "proto3";option csharp_namespace = "GrpcProject";package grpc.serviceing;// 服务端流对应的请求流和响应流message FileInfoRequest
{string fileName = 1;
}message FileInfoResponse
{string fileName = 1;int64 fileSize = 2;string extension = 3;
}message ProgressBarResponse
{FileInfoResponse fileMessage = 1;bytes fileBytes = 2;
}// serverstream.proto定义service方法syntax = "proto3";import "google/protobuf/empty.proto";
import "Protos/messages.proto";option csharp_namespace = "GrpcProject";package grpc.serviceing;service ServerStreamRpc{// 一元文件获取展示rpc GetFileMessage(google.protobuf.Empty) returns (FileInfoResponse);// 服务端文件流处理rpc StreamingFromServer	(FileInfoRequest) returns (stream ProgressBarResponse);
}

服务接口实现：

    public class ServerStreamService : ServerStreamRpc.ServerStreamRpcBase{/// <summary>/// 获取文件信息/// </summary>/// <param name="request">空请求</param>/// <param name="context">服务调用上下文</param>/// <returns></returns>public override Task<FileInfoResponse> GetFileMessage(Empty request, ServerCallContext context){var filePath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Files", "cn-Liang-y.rar");FileInfo fileInfo = new FileInfo(filePath);FileInfoResponse fileInfoResponse = new FileInfoResponse();fileInfoResponse.FileName = fileInfo.Name;fileInfoResponse.FileSize = fileInfo.Length;fileInfoResponse.Extension = fileInfo.Extension;return Task.FromResult(fileInfoResponse);}public override async Task StreamingFromServer(FileInfoRequest request,IServerStreamWriter<ProgressBarResponse> responseStream,ServerCallContext context){var filePath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Files", request.FileName);if (!File.Exists(filePath)){throw new FileNotFoundException(nameof(filePath));}// 进度条按照 100百分比进行划分FileInfo fileInfo = new FileInfo(filePath);using var fileStream = fileInfo.OpenRead();// 插入固定长度int fixedLength = (int)fileStream.Length / 100;byte[] fileBytes = new byte[fixedLength];int len;while ((len = fileStream.Read(fileBytes, 0, fixedLength)) > 0){await Console.Out.WriteLineAsync($"打印字节长度：{len}");var response = new ProgressBarResponse();response.FileMessage = new FileInfoResponse{FileName = fileInfo.Name,FileSize = fileInfo.Length,Extension = fileInfo.Extension};response.FileBytes = ByteString.CopyFrom(fileBytes);await responseStream.WriteAsync(response);}}}

Program注入：

    public class Program{public static void Main(string[] args){var builder = WebApplication.CreateBuilder(args);builder.Services.AddGrpc();var app = builder.Build();// 一元方法//app.MapGrpcService<DollarService>();// 客户端流//app.MapGrpcService<ClientStreamService>();// 服务端流app.MapGrpcService<ServerStreamService>();app.Run();}}

四、客户端配置

1. 引用proto文件，配置为客户端类型
2. 根据编译生成的函数进行传参调用
3. 创建WPF客户端提供控制条显示

 button按钮触发grpc

        private async void download_Click(object sender, RoutedEventArgs e){Action<int> action = async i =>{progressBar.Value = i;await Task.Delay(100);};await WpfClient.Show(action);}

grpc客户端接口调用

    public class WpfClient{public static async Task Show(Action<int> action){var channel = GrpcChannel.ForAddress("https://localhost:7188");var client = new GrpcProject.ServerStreamRpc.ServerStreamRpcClient(channel);var fileMessage = await client.GetFileMessageAsync(new Google.Protobuf.WellKnownTypes.Empty());FileInfoRequest request = new FileInfoRequest();request.FileName = fileMessage.FileName;var streaming = client.StreamingFromServer(request);var path = Path.Combine(Directory.GetCurrentDirectory(), "test.rar");using var stream = new FileStream(path, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite);int i = 0;await foreach (var item in streaming.ResponseStream.ReadAllAsync()){stream.Write(item.FileBytes.Span);action(i++);}stream.Flush();stream.Close();}}

五、执行结果

 在文件根目录可以看到下载的文件

 六、源码地址

链接：https://pan.baidu.com/s/13_AEFHLLJS5qN8aIby8IsA 
提取码：72x0