GRPC java實現demo

一、環境 

       jdk8+maven+IDEA

二、 我的理解+官方文檔

       1、官方文檔:https://codelabs.developers.google.com/codelabs/cloud-grpc-java/index.html#2

       2、我的理解：grpc是利用.proto文件用相應的語言編譯生成相應的代碼，這樣就能實現不同語言平臺之間的調用。最神奇的是彷彿客戶端和服務器端調用的是相同的函數，在相同函數裏面實現通信，相當的容易理解。

三、我的github+代碼

     1、github鏈接：https://github.com/cysisu/grpc-java.git

     2、代碼如下：

           （1）pop.xml

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>com.grpc.cube</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>io.grpc</groupId>
            <artifactId>grpc-netty</artifactId>
            <version>1.7.0</version>
        </dependency>
        <dependency>
            <groupId>io.grpc</groupId>
            <artifactId>grpc-protobuf</artifactId>
            <version>1.7.0</version>
        </dependency>
        <dependency>
            <groupId>io.grpc</groupId>
            <artifactId>grpc-stub</artifactId>
            <version>1.7.0</version>
        </dependency>
    </dependencies>

    <build>
        <extensions>
            <extension>
                <groupId>kr.motd.maven</groupId>
                <artifactId>os-maven-plugin</artifactId>
                <version>1.5.0.Final</version>
            </extension>
        </extensions>
        <plugins>
            <plugin>
                <groupId>org.xolstice.maven.plugins</groupId>
                <artifactId>protobuf-maven-plugin</artifactId>
                <version>0.5.0</version>
                <configuration>
                    <protocArtifact>com.google.protobuf:protoc:3.4.0:exe:${os.detected.classifier}</protocArtifact>
                    <pluginId>grpc-java</pluginId>
                    <pluginArtifact>io.grpc:protoc-gen-grpc-java:1.7.0:exe:${os.detected.classifier}</pluginArtifact>
                </configuration>
                <executions>
                    <execution>
                        <goals>
                            <goal>compile</goal>
                            <goal>compile-custom</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

</project>

                (2) 客戶端：

              

package com.example.grpc;

import io.grpc.*;

public class Client
{
    public static void main( String[] args ) throws Exception
    {
        // Channel is the abstraction to connect to a service endpoint
        // Let's use plaintext communication because we don't have certs
        final ManagedChannel channel = ManagedChannelBuilder.forTarget("localhost:8080")
                .usePlaintext(true)
                .build();

        // It is up to the client to determine whether to block the call
        // Here we create a blocking stub, but an async stub,
        // or an async stub with Future are always possible.
        GreetingServiceGrpc.GreetingServiceBlockingStub stub = GreetingServiceGrpc.newBlockingStub(channel);
        GreetingServiceOuterClass.HelloRequest request =
                GreetingServiceOuterClass.HelloRequest.newBuilder()
                        .setName("Ray")
                        .build();

        // Finally, make the call using the stub
        GreetingServiceOuterClass.HelloResponse response =
                stub.greeting(request);

        System.out.println(response);

        // A Channel should be shutdown before stopping the process.
        channel.shutdownNow();
    }
}

 

       （3）服務器端調用的函數：

package com.example.grpc;

import io.grpc.stub.StreamObserver;

public class GreetingServiceImpl extends GreetingServiceGrpc.GreetingServiceImplBase {
    public void greeting(GreetingServiceOuterClass.HelloRequest request,
                         StreamObserver<GreetingServiceOuterClass.HelloResponse> responseObserver) {
        // HelloRequest has toString auto-generated.
        System.out.println(request);

        // You must use a builder to construct a new Protobuffer object
        GreetingServiceOuterClass.HelloResponse response = GreetingServiceOuterClass.HelloResponse.newBuilder()
                .setGreeting("Hello there, " + request.getName())
                .build();

        // Use responseObserver to send a single response back
        responseObserver.onNext(response);

        // When you are done, you must call onCompleted.
        responseObserver.onCompleted();
    }
}

        （5）服務器端：

package com.example.grpc;
import io.grpc.*;

public class App
{
    public static void main( String[] args ) throws Exception
    {
        // Create a new server to listen on port 8080
        Server server = ServerBuilder.forPort(8080)
                .addService(new GreetingServiceImpl())
                .build();


        // Start the server
        server.start();

        // Server threads are running in the background.
        System.out.println("Server started");
        // Don't exit the main thread. Wait until server is terminated.
        server.awaitTermination();
    }
}

       （6）proto文件：

    

syntax = "proto3";
package com.example.grpc;

// Request payload
message HelloRequest {
    // Each message attribute is strongly typed.
    // You also must assign a "tag" number.
    // Each tag number is unique within the message.
    string name = 1;

    // This defines a strongly typed list of String
    repeated string hobbies = 2;

    // There are many more basics types, like Enum, Map
    // See https://developers.google.com/protocol-buffers/docs/proto3
    // for more information.
}

message HelloResponse {
    string greeting = 1;
}

// Defining a Service, a Service can have multiple RPC operations
service GreetingService {
    // Define a RPC operation
    rpc greeting(HelloRequest) returns (HelloResponse);
}