grpc的java实现，从无到有

た入场券 2022-06-15 01:28 194阅读 0赞

# 1、Eclipse创建Maven项目 #

新建一个空的maven工程（不选archetype）。

# 2、修改POM文件 #

增加grpc的依赖

<dependencies>
    		<dependency>
    			<groupId>io.grpc</groupId>
    			<artifactId>grpc-all</artifactId>
    			<version>${grpc-version}</version>
    		</dependency>
    	</dependencies>

增加protocol buffers编译插件项:

<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:${os.detected.classifier}</protocArtifact>
    					<pluginId>grpc-java</pluginId>
    					<pluginArtifact>io.grpc:protoc-gen-grpc-java:0.14.0:exe:${os.detected.classifier}</pluginArtifact>
    				</configuration>
    				<executions>
    					<execution>
    						<goals>
    							<goal>compile</goal>
    							<goal>compile-custom</goal>
    						</goals>
    					</execution>
    				</executions>
    			</plugin>
    		</plugins>
    	</build>

其中，上面黄底红字的部分，我们的protoc的版本要和protobuf-[Java ][Java]jar包的版本一致。也就是说我们这里如果写了3.0.0(第一个黄底红字,注：我这里给出的例子使用的是3.0.0-beta-2)

配置文件中给出的

${os.detected.classifier}

在我的机器上被解析为 windows-x86\_64 了，这些都是上边的那个扩展插件的作用

# 3、编写服务.proto文件（hello.proto） #

先在src/main目录下新建一个文件夹proto，用来存放我们马上将要创建的proto文件。

syntax = "proto3";
    
    option java_multiple_files = true;
    option java_package = "com.jasper.grpc.hello";
    option java_outer_classname = "HelloWorldProto";
    
    package helloworld;
    
    service Greeter {
      rpc SayHello (HelloRequest) returns (HelloReply) {}
    }
    
    message HelloRequest {
      string name = 1;
    }
    
    message HelloReply {
      string message = 1;
    }

# 4、编译.proto文件 #

有两种方式：

1、通过eclipse maven插件进行安装编译  maven install

2、通过protoc.exe执行文件，进行编译（proto和exe文件放在同一目录下）

指令为：protoc --java\_out=./dd test.proto

（不同目录下,例如 protoc \--java\_out=./src ./msg/hello.proto）

最后，由于生成的代码中有

@java.lang.Override

这种注释，在JDK1.8中有问题，可以修改jdk语言级别为6 或者 直接去掉

# 5、编写grpc 服务端HelloWorldServer.java #

import java.io.IOException;
    
    import com.jasper.grpc.hello.GreeterGrpc;
    import com.jasper.grpc.hello.HelloReply;
    import com.jasper.grpc.hello.HelloRequest;
    
    import io.grpc.Server;
    import io.grpc.ServerBuilder;
    import io.grpc.stub.StreamObserver;
    
    public class HelloWorldServer {
    
    	private int port = 88051;
        private Server server;
    
        private void start() throws IOException {
            server = ServerBuilder.forPort(port)
                    .addService(new GreeterImpl())
                    .build()
                    .start();
    
            System.out.println("service start...");
    
            Runtime.getRuntime().addShutdownHook(new Thread() {
    
                @Override
                public void run() {
    
                    System.err.println("*** shutting down gRPC server since JVM is shutting down");
                    HelloWorldServer.this.stop();
                    System.err.println("*** server shut down");
                }
            });
        }
    
        private void stop() {
            if (server != null) {
                server.shutdown();
            }
        }
    
        // block 一直到退出程序 
        private void blockUntilShutdown() throws InterruptedException {
            if (server != null) {
                server.awaitTermination();
            }
        }
    
    
        public static void main(String[] args) throws IOException, InterruptedException {
    
            final HelloWorldServer server = new HelloWorldServer();
            server.start();
            server.blockUntilShutdown();
        }
    
    
        // 实现 定义一个实现服务接口的类 
        private class GreeterImpl extends GreeterGrpc.AbstractGreeter {
    
    
            public void sayHello(HelloRequest req, StreamObserver<HelloReply> responseObserver) {
                System.out.println("service:"+req.getName());
                HelloReply reply = HelloReply.newBuilder().setMessage(("Hello: " + req.getName())).build();
                responseObserver.onNext(reply);
                responseObserver.onCompleted();
            }
        }
    	
    }

# 6、编写grpc 客户端 HelloWorldClient.java #

import java.util.concurrent.TimeUnit;
    
    import com.jasper.grpc.hello.GreeterGrpc;
    import com.jasper.grpc.hello.HelloReply;
    import com.jasper.grpc.hello.HelloRequest;
    
    import io.grpc.ManagedChannel;
    import io.grpc.ManagedChannelBuilder;
    
    public class HelloWorldClient {
    
    	private final ManagedChannel channel; 
        private final GreeterGrpc.GreeterBlockingStub blockingStub; 
    
    
        public HelloWorldClient(String host,int port){ 
            channel = ManagedChannelBuilder.forAddress(host,port) 
                    .usePlaintext(true) 
                    .build();
    
            blockingStub = GreeterGrpc.newBlockingStub(channel); 
        }
    
    
        public void shutdown() throws InterruptedException { 
            channel.shutdown().awaitTermination(5, TimeUnit.SECONDS); 
        }
    
        public  void greet(String name){ 
            HelloRequest request = HelloRequest.newBuilder().setName(name).build(); 
            HelloReply   response = blockingStub.sayHello(request);
            System.out.println(response.getMessage());
    
        }
    
        public static void main(String[] args) throws InterruptedException { 
            HelloWorldClient client = new HelloWorldClient("127.0.0.1",88051);
            for(int i=0;i<5;i++){
                client.greet("world:"+i);
            }
    
    
        }
    	
    }

参考：http://blog.csdn.net/lyjshen/article/details/52238234\#t1

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