gRPC快速入门-蒲公英云

gRPC 是一个高性能、开源和通用的 RPC 框架，面向移动和 HTTP/2 设计。目前提供 C、Java 和 Go 语言版本，分别是：grpc, grpc-java, grpc-go. 其中 C 版本支持 C, C++, Node.js, Python, Ruby, Objective-C, PHP 和 C# 支持.

gRPC 基于 HTTP/2 标准设计，带来诸如双向流、流控、头部压缩、单 TCP 连接上的多复用请求等特。这些特性使得其在移动设备上表现更好，更省电和节省空间占用。

研究gRPC之前，需要先熟悉Protocol Buffers

Protocol Buffers (ProtocolBuffer/ protobuf )是Google公司开发的一种数据描述语言，类似于XML能够将结构化数据序列化，可用于数据存储、通信协议等方面。现阶段支持C++、JAVA、Python等三种编程语言。

一：编写IDL文件 send_mail.proto

syntax = "proto3";
option java_multiple_files = true;
option java_package = "com.rpc.mail";
option java_outer_classname = "SendMailServiceProto";
message SendMailRequest {
    string recipient = 1;
    string title = 2;
    string content = 3;
}
message SendMailResponse {
    int32 code = 1;
    string msg = 2;
}
service SendMailService {
    rpc sendMail (SendMailRequest) returns (SendMailResponse) {}
}

这里定义了一个请求参数SendMailRequest，一个返回参数SendMailResponse，一个接口SendMailService

新建一个maven项目，把上面的proto文件放到src/main/proto目录

pom.xml里面增加如下配置

<dependencies>
    <dependency>
        <groupId>io.grpc</groupId>
        <artifactId>grpc-all</artifactId>
        <version>0.14.1</version>
    </dependency>
</dependencies>
<build>
    <extensions>
        <extension>
            <groupId>kr.motd.maven</groupId>
            <artifactId>os-maven-plugin</artifactId>
            <version>1.4.1.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:3.0.0-beta-2:exe:${os.detected.classifier}
                </protocArtifact>
                <pluginId>grpc-java</pluginId>
                <pluginArtifact>io.grpc:protoc-gen-grpc-java:0.14.1:exe:${os.detected.classifier}
                </pluginArtifact>
            </configuration>
            <executions>
                <execution>
                    <goals>
                        <goal>compile</goal>
                        <goal>compile-custom</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

之后执行maven clean package即可生成java代码，生成的java代码在target\generated-sources\protobuf 目录

注意：插件里面的protobuf（protocArtifact、pluginArtifact）需要和grpc-core里面依赖的protobuf版本需要保持一致

二：编码

新建一个maven项目（也可以直接使用上一步创建的项目），在pom.xml里面加入如下配置

<dependencies>
    <dependency>
        <groupId>io.grpc</groupId>
        <artifactId>grpc-all</artifactId>
        <version>0.14.1</version>
    </dependency>
</dependencies>

然后把target\generated-sources\protobuf\java 和 target\generated-sources\protobuf\grpc-java 里面的代码放到src目录中去
目录结构如下：

Center

接下来，写接口的实现类

package com.rpc.mail;
import io.grpc.stub.StreamObserver;
public class SendMailServiceImpl implements SendMailServiceGrpc.SendMailService {
    public void sendMail(SendMailRequest request, StreamObserver<SendMailResponse> responseObserver) {
        System.out.println(request.getRecipient() + "\t" + request.getTitle() + "\t" + request.getContent());
        //这里是具体的业务逻辑
        SendMailResponse resp = SendMailResponse.newBuilder().setCode(0).setMsg("OK").build();
        //设置返回结果
        responseObserver.onNext(resp);
        responseObserver.onCompleted();    
    }
}

服务端：

package com.rpc.mail;
import io.grpc.Server;
import io.grpc.netty.NettyServerBuilder;
public class GrpcServer {
    public static void main(String[] args) throws Exception {
        Server server = NettyServerBuilder.forPort(8080).addService(SendMailServiceGrpc.bindService(new SendMailServiceImpl())).build();
        server.start();
        System.out.println("server startup at 8080");
        server.awaitTermination();
    }
}

客户端：

package com.rpc.mail;
import java.util.concurrent.TimeUnit;
import com.rpc.mail.SendMailServiceGrpc.SendMailServiceBlockingStub;
import io.grpc.ManagedChannel;
import io.grpc.netty.NettyChannelBuilder;
public class GrpcClient {
    public static void main(String[] args) throws Exception {
        ManagedChannel channel = NettyChannelBuilder.forAddress("127.0.0.1", 8080).usePlaintext(true).build();
        //同步调用(异步调用的话，就是：SendMailServiceGrpc.newFutureStub(channel))
        SendMailServiceBlockingStub stub = SendMailServiceGrpc.newBlockingStub(channel);
        //设置请求参数
        SendMailRequest param = SendMailRequest.newBuilder().setRecipient("admin@google.com").setTitle("运维邮件").setContent("SOA服务挂了").build();
        SendMailResponse resp = stub.sendMail(param);
        System.out.println(resp.getMsg() + "\t" + resp.getCode());
        //close
        channel.shutdown().awaitTermination(1, TimeUnit.SECONDS);
    }
}