第三节（grpc1.18.0 在JAVA中调用c++发布的服务） Java

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第一节入门：https://blog.csdn.net/shan165310175/article/details/86618932
第二节C++编译helloworld工程：https://blog.csdn.net/shan165310175/article/details/86619128

0. 建立maven工程(使用Idea ide)
1.maven添加依赖和插件：

io.grpc grpc-netty-shaded 1.18.0 io.grpc grpc-protobuf 1.18.0 io.grpc grpc-stub 1.18.0 kr.motd.maven os-maven-plugin 1.5.0.Final org.xolstice.maven.plugins protobuf-maven-plugin 0.5.1 com.google.protobuf:protoc:3.5.1-1:exe:${os.detected.classifier}grpc-javaio.grpc:protoc-gen-grpc-java:1.17.1:exe:${os.detected.classifier} compile compile-custom

如果出现插件爆红，下载不下来的，那么将代码贴到dependency中：

org.xolstice.maven.plugins protobuf-maven-plugin 0.5.1

下载完之后再删除。
此时插件那边显示：

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2. 建立main/proto目录，将helloworld.proto拷贝到目录中
3.双击上面的编译命令编译proto文件，生成如下文件：

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4.新建HelloworldClient类，内容如下：

package com.daily; import io.grpc.ManagedChannel; import io.grpc.ManagedChannelBuilder; import io.grpc.StatusRuntimeException; import io.grpc.examples.helloworld.GreeterGrpc; import io.grpc.examples.helloworld.HelloReply; import io.grpc.examples.helloworld.HelloRequest; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import java.util.concurrent.TimeUnit; import java.util.logging.Level; import java.util.logging.Logger; public class HelloWorldClient { private static final Logger logger = Logger.getLogger(HelloWorldClient.class.getName()); private final ManagedChannel channel; private final GreeterGrpc.GreeterBlockingStub blockingStub; // private final GreeterGrpc.GreeterFutureStub blockingStub; /** Construct client connecting to HelloWorld server at {@code host:port}. */ public HelloWorldClient(String host, int port) { this(ManagedChannelBuilder.forAddress(host, port) // Channels are secure by default (via SSL/TLS). For the example we disable TLS to avoid // needing certificates. .usePlaintext() .build()); } /** Construct client for accessing HelloWorld server using the existing channel. */ HelloWorldClient(ManagedChannel channel) { this.channel = channel; blockingStub = GreeterGrpc.newBlockingStub(channel); //blockingStub = GreeterGrpc.newFutureStub(channel); } public void shutdown() throws InterruptedException { channel.shutdown().awaitTermination(5, TimeUnit.SECONDS); } private ExecutorService threadPool = Executors.newFixedThreadPool(30); /** Say hello to server. */ public void greet(String name) { //logger.info("Will try to greet " + name + " ..."); HelloRequest request = HelloRequest.newBuilder().setName(name).build(); HelloReply response; try {HelloReply helloReply = blockingStub.sayHello(request); System.out.println(helloReply.getMessage()); } catch (StatusRuntimeException e) { logger.log(Level.WARNING, "RPC failed: {0}", e.getStatus()); return; } //System.out.println("Greeting: " + response.getMessage()); } /** * Greet server. If provided, the first element of {@code args} is the name to use in the * greeting. */ public static void main(String[] args) throws Exception {HelloWorldClient client = new HelloWorldClient("localhost", 50051); try { for (int i = 0; i < 5; ++i) { client.greet("小明"+i); } System.out.println("end>>>>>>>>>>>>>>>>>>>>>>>"); } finally { client.shutdown(); }Thread.sleep(5000); } }

main函数中就是主要调用，该调用是同步的。
注释部分有异步的。blockingStub = GreeterGrpc.newFutureStub(channel);
开启c++服务：