一、了解grpc

谷歌开源远程进程调用框架，支持多语言系统间通信，适用于各种分布式系统，使用http2协议并使用protobuf系列化通信数据，高性能。nacos2开始也集成了grpc，用于nacos server与nacos client间通信。grpc还支持了client-server双向流，两个流可独立不阻塞进行连续读写。

二、关于protobuf

如果只是protobuf作为序列化方案，建议使用protostuff（基于protobuf），不用写proto文件。grpc官方的quickstart都是直接使用protobuf，故这里暂不研究是否有grpc+protostuff方案。Java 有maven插件进行proto文件生成Java文件，故不用单独去安装proto了，但proto基本语法还得了解。

三、试玩grpc

官方的quickstart不是基于springboot的，故这里就参考这位大佬的JAVA使用gRPC
，为方便使用，这里server，client都在同一个工程里。如果要分开，则在独立项目中引入grpc-client-spring-boot-starter 等依赖并，并copy需要的类com.example.demo.protogen.UserServiceGrpc,com.example.demo.protogen.User等。

3.1整个工程目录

在这里插入图片描述

3.2 proto文件编写

proto里放file.proto,message.proto文件如下

syntax = "proto3";package protogen;
option java_package = "com.example.demo.protogen";message File {string name = 1;int32 size = 2;
}

syntax = "proto3";
package protogen;import "file.proto";option java_multiple_files = true;
option java_package = "com.example.demo.protogen";message User {reserved 6 to 7;reserved "userId2";int32 userId = 1;string username = 2;oneof msg {string error = 3;int32 code = 4;}string name = 8;UserType userType = 9;repeated int32 roles = 10;protogen.File file = 11;map<string, string> hobbys = 12;
}enum UserType {UNKNOW = 0;ADMIN = 1;BUSINESS_USER = 2;
};service UserService {rpc getUser (User) returns (User) {}rpc getUsers (User) returns (stream User) {}rpc saveUsers (stream User) returns (User) {}
}service FileService {rpc getFile(User) returns(File) {}
}

3.3 使用maven protobuf插件转换.proto文件

protogen里文件都是生成的，插件配置了读取这个目录，并生成到protogen文件夹里。通过点击如图插件按钮实现，protobuf:compile实际是通过proto.exe将.proto文件生成Java文件，除了FileServiceGrpc，UserServiceGrpc是protobuf:compile-custom生成的，其余都是protobuf:compile生成的。

3.4 Grpc服务端业务实现类

UserServiceImpl.java

package com.example.demo.grpc.server;import com.example.demo.protogen.User;
import com.example.demo.protogen.UserServiceGrpc;
import io.grpc.stub.StreamObserver;
import net.devh.boot.grpc.server.service.GrpcService;/*** @author Kone* @date 2022/1/29*/
@GrpcService
public class UserServiceImpl extends UserServiceGrpc.UserServiceImplBase {@Overridepublic void getUser(User request, StreamObserver<User> responseObserver) {System.out.println(request);User user = User.newBuilder().setName("response name").build();responseObserver.onNext(user);responseObserver.onCompleted();}@Overridepublic void getUsers(User request, StreamObserver<User> responseObserver) {System.out.println("get users");System.out.println(request);User user = User.newBuilder().setName("user1").build();User user2 = User.newBuilder().setName("user2").build();responseObserver.onNext(user);responseObserver.onNext(user2);responseObserver.onCompleted();}@Overridepublic StreamObserver<User> saveUsers(StreamObserver<User> responseObserver) {return new StreamObserver<User>() {@Overridepublic void onNext(User user) {System.out.println("get saveUsers list ---->");System.out.println(user);}@Overridepublic void onError(Throwable throwable) {System.out.println("saveUsers error " + throwable.getMessage());}@Overridepublic void onCompleted() {User user = User.newBuilder().setName("saveUsers user1").build();responseObserver.onNext(user);responseObserver.onCompleted();}};}
}

3.5 pom参考

springboot3有点问题，暂用2.7.9版本springboot

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://maven.apache.org/POM/4.0.0"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.7.9</version><relativePath/> </parent><groupId>com.example</groupId><artifactId>demo</artifactId><version>0.0.1-SNAPSHOT</version><name>demo</name><description>Demo project for Spring Boot</description><properties><java.version>17</java.version><protobuf.version>3.23.4</protobuf.version><grpc.version>1.26.0</grpc.version></properties><dependencies><!-- https://mvnrepository.com/artifact/com.google.protobuf/protobuf-java --><dependency><groupId>com.google.protobuf</groupId><artifactId>protobuf-java</artifactId><version>${protobuf.version}</version></dependency><!-- grpc server和spring-boot集成框架 --><dependency><groupId>net.devh</groupId><artifactId>grpc-server-spring-boot-starter</artifactId><version>2.14.0.RELEASE</version></dependency><!-- grpc client和spring-boot集成框架 --><dependency><groupId>net.devh</groupId><artifactId>grpc-client-spring-boot-starter</artifactId><version>2.14.0.RELEASE</version></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>1.18.22</version><optional>true</optional></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId></dependency></dependencies><build><!-- os系统信息插件, protobuf-maven-plugin需要获取系统信息下载相应的protobuf程序 --><extensions><extension><groupId>kr.motd.maven</groupId><artifactId>os-maven-plugin</artifactId><version>1.6.2</version></extension></extensions><plugins><plugin><groupId>org.xolstice.maven.plugins</groupId><artifactId>protobuf-maven-plugin</artifactId><version>0.6.1</version><configuration><!--os.detected.classifier属性是通过如上os-maven-plugin插件获取的--><protocArtifact>com.google.protobuf:protoc:${protobuf.version}:exe:${os.detected.classifier}</protocArtifact><pluginId>grpc-java</pluginId><pluginArtifact>io.grpc:protoc-gen-grpc-java:${grpc.version}:exe:${os.detected.classifier}</pluginArtifact><!-- proto文件目录 --><protoSourceRoot>${project.basedir}/src/main/java/com/example/demo/proto</protoSourceRoot><!-- 生成的Java文件目录,这里指定到这一级就可以咯，proto文件有基于package指定 --><outputDirectory>${project.basedir}/src/main/java</outputDirectory><clearOutputDirectory>false</clearOutputDirectory></configuration><executions><execution><goals><goal>compile</goal><goal>compile-custom</goal></goals></execution></executions></plugin><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId><configuration><excludes><exclude><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId></exclude></excludes></configuration></plugin><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-compiler-plugin</artifactId><configuration><source>17</source><target>17</target></configuration></plugin></plugins></build>
</project>

3.6 grpc client调用

基于grpc server的URL直接调用

package com.example.demo;import com.example.demo.protogen.User;
import com.example.demo.protogen.UserServiceGrpc;
import io.grpc.ManagedChannel;
import io.grpc.ManagedChannelBuilder;import java.util.Iterator;public class FramelessGrpcClient {public static void main(String[] args) {ManagedChannel managedChannel = ManagedChannelBuilder.forAddress("localhost", 9090).usePlaintext().build();UserServiceGrpc.UserServiceBlockingStub userService = UserServiceGrpc.newBlockingStub(managedChannel);User user = User.newBuilder().setUserId(100).putHobbys("pingpong", "play pingpong").setCode(200).build();System.out.println("get response-------->");System.out.println(userService.getUser(user));Iterator<User> users = userService.getUsers(user);}
}

从spring IOC注入bean来调用grpc server (yml里配置了URL等)。这里使用定时任务来触发调度。注意注入的“userClient”需要与yml 自定义的client名一致（如果调用多个grpc server，这个自定义名就是用来区别调用哪个grpc server滴）。

package com.example.demo;import com.example.demo.protogen.User;
import com.example.demo.protogen.UserServiceGrpc;
import net.devh.boot.grpc.client.inject.GrpcClient;
import org.springframework.scheduling.annotation.EnableScheduling;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;import java.util.Iterator;/*** TODO** @author majun* @version 1.0* @since 2023-08-02 20:19*/
@Component
@EnableScheduling
public class SpringbootGrpcClient {@GrpcClient("userClient")private UserServiceGrpc.UserServiceBlockingStub userService;@Scheduled(fixedDelay = 10000)public void test() {User user = User.newBuilder().setUserId(100).putHobbys("pingpong", "play pingpong").setCode(200).build();System.out.println("get response-------->");System.out.println(userService.getUser(user));Iterator<User> users = this.userService.getUsers(user);while (users.hasNext()) {System.out.println(users.next());}}
}