说明：

GRPC是什么？

首先我们知道 RPC是远程过程调用。

而GRPC是RPC的一种实现。

那么为什么要用GRPC呢？

因为它支持跨语言的开发，换句话说，大家都用过FeignRPC，尤其在spring cloud中。

然而它只支持java语言，而作为微服务，可能有很多其他的服务不是java开发的。因此需要满足这个需求，就需要一个跨语言的RPC，所以就会考虑使用GRPC

好了，下面进入正题

直接上代码。

我们做一个Service和一个Client 进行交互。

一，Service端

1，POM

注意：

grpc-spring-boot-starter

os-maven-plugin

protobuf-maven-plugin

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         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>2.5.6</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.leadtrans</groupId>
    <artifactId>report</artifactId>
    <version>1.6.0</version>
    <name>report</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>11</java.version>
        <spring-cloud.version>2020.0.4</spring-cloud.version>
        <!--    GRPC    -->
        <grpc-spring-boot-starter.version>2.3.2</grpc-spring-boot-starter.version>
        <os-maven-plugin.version>1.6.0</os-maven-plugin.version>
        <protobuf-maven-plugin.version>0.5.1</protobuf-maven-plugin.version>
    </properties>
    <dependencies>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <!-- https://mvnrepository.com/artifact/com.alibaba/fastjson -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.78</version>
        </dependency>

        <!--    GRPC    -->
        <dependency>
            <groupId>org.lognet</groupId>
            <artifactId>grpc-spring-boot-starter</artifactId>
            <version>${grpc-spring-boot-starter.version}</version>
        </dependency>

    </dependencies>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <build>
        <extensions>
            <!-- os-maven-plugin -->
            <extension>
                <groupId>kr.motd.maven</groupId>
                <artifactId>os-maven-plugin</artifactId>
                <version>${os-maven-plugin.version}</version>
            </extension>
        </extensions>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-surefire-plugin</artifactId>
                <configuration>
                    <skip>true</skip>
                </configuration>
            </plugin>
            <!-- protobuf-maven-plugin -->
            <plugin>
                <groupId>org.xolstice.maven.plugins</groupId>
                <artifactId>protobuf-maven-plugin</artifactId>
                <version>${protobuf-maven-plugin.version}</version>
                <configuration>
                    <protocArtifact>com.google.protobuf:protoc:3.5.1-1:exe:${os.detected.classifier}</protocArtifact>
                    <pluginId>grpc-java</pluginId>
                    <pluginArtifact>io.grpc:protoc-gen-grpc-java:1.11.0:exe:${os.detected.classifier}</pluginArtifact>
                    <outputDirectory>${project.build.sourceDirectory}</outputDirectory>
                    <clearOutputDirectory>false</clearOutputDirectory>
                </configuration>
                <executions>
                    <execution>
                        <goals>
                            <goal>compile</goal>
                            <goal>compile-custom</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

</project>

2，创建Proto

PS：Proto文件夹，必须和JAVA同级！

 HelloWorld.protp

PS:请使用 option java_package="xxxx"，

而不是 package xxxx

package xxxx 会导致你引用其他包时，会报错

syntax = "proto3";

option java_multiple_files = true;
option java_package="com.example.test.helloworld";

//请求
message Request {
  double num1 = 1;
  double num2 = 2;
  OperateType opType = 3;
}

//操作类型
enum OperateType {
  Addition = 0;
  Division = 1;
  Multiplication = 2;
  Subtraction = 3;
}
message Response {
  double result = 1;
}

//定义服务
service Operate {
  rpc Calculate (Request) returns (Response);
}

3，执行命令，生成文件

mvn clean install

或者点击

可以看到生成了文件：

4，实现接口

为了简单演示，这里就直接设置Response.Result=2

OperateImpl

@GRpcService
public class OperateImpl extends OperateGrpc.OperateImplBase {
    @Override
    public void calculate(Request request,
                          StreamObserver<Response> responseObserver) {
        Response response=Response.newBuilder().setResult(2).build();
        System.out.println(response);
        responseObserver.onNext(response);
        responseObserver.onCompleted();
    }
}

 二，Client端

 1，POM（同Service端）

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         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>2.5.6</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>test1</artifactId>
    <version>1.0</version>
    <name>test1</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>11</java.version>
        <spring-cloud.version>2021.0.0</spring-cloud.version>
        <grpc-spring-boot-starter.version>2.3.2</grpc-spring-boot-starter.version>
        <os-maven-plugin.version>1.6.0</os-maven-plugin.version>
        <protobuf-maven-plugin.version>0.5.1</protobuf-maven-plugin.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <!-- grpc -->
        <dependency>
            <groupId>org.lognet</groupId>
            <artifactId>grpc-spring-boot-starter</artifactId>
            <version>${grpc-spring-boot-starter.version}</version>
        </dependency>
    </dependencies>

    <build>
        <extensions>
            <!-- os-maven-plugin -->
            <extension>
                <groupId>kr.motd.maven</groupId>
                <artifactId>os-maven-plugin</artifactId>
                <version>${os-maven-plugin.version}</version>
            </extension>
        </extensions>
        <plugins>
            <!-- spring-boot-maven-plugin -->
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
            <!-- protobuf-maven-plugin -->
            <plugin>
                <groupId>org.xolstice.maven.plugins</groupId>
                <artifactId>protobuf-maven-plugin</artifactId>
                <version>${protobuf-maven-plugin.version}</version>
                <configuration>
                    <protocArtifact>com.google.protobuf:protoc:3.5.1-1:exe:${os.detected.classifier}</protocArtifact>
                    <pluginId>grpc-java</pluginId>
                    <pluginArtifact>io.grpc:protoc-gen-grpc-java:1.11.0:exe:${os.detected.classifier}</pluginArtifact>
                    <outputDirectory>${project.build.sourceDirectory}</outputDirectory>
                    <clearOutputDirectory>false</clearOutputDirectory>
                </configuration>
                <executions>
                    <execution>
                        <goals>
                            <goal>compile</goal>
                            <goal>compile-custom</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

</project>

2，拷贝Proto

和java同级目录

3，执行命令

mvn clean install

4，调用方法

CalculateService

其中 main方法，是测试方法。

GRPC启动的默认端口是6565，在main中设置了。

public class CalculateService {
    private final ManagedChannel channel;
    private final OperateGrpc.OperateBlockingStub blockingStub;

    private CalculateService(ManagedChannel channel) {
        this.channel = channel;
        blockingStub = OperateGrpc.newBlockingStub(channel);
    }

    public CalculateService(String host, int port) {
        this(ManagedChannelBuilder.forAddress(host, port)
                .usePlaintext()
                .build());
    }

    public void shutdown() throws InterruptedException {
        channel.shutdown().awaitTermination(5, TimeUnit.SECONDS);
    }

    public float operate(float num1, float num2, OperateType operateType) {
        Request request = Request.newBuilder().setNum1(num1).setNum2(num2).setOpType(operateType).build();
        Response response = blockingStub.calculate(request);
        return (float) response.getResult();
    }

    public static void main(String[] args) {
        try {
            CalculateService service = new CalculateService("localhost", 6565);
            System.out.println(service.operate(100, 0, OperateType.Division));
            service.shutdown();
        } catch (Exception e) {
            System.out.println(e);
        }
    }

}

三，结果