grpc-java示例
学习一门新技术最好的途径是看官方文档,认真看,技术书籍的原始材料就是来源于官方文档,很多网上的教程有些时候是查考官方文档的,但是描述的不准确,就形成了以讹传讹的情况,所以想看最准确的技术表述,就去看官方文档吧。
该文章是通过收集https://github.com/grpc/grpc-java上的材料完成的。
1.创建maven项目,添加项目依赖
<dependency> <groupId>io.grpc</groupId> <artifactId>grpc-netty</artifactId> <version>1.11.0</version> </dependency> <dependency> <groupId>io.grpc</groupId> <artifactId>grpc-protobuf</artifactId> <version>1.11.0</version> </dependency> <dependency> <groupId>io.grpc</groupId> <artifactId>grpc-stub</artifactId> <version>1.11.0</version> </dependency>
2.编写proto文件
syntax = "proto3"; option java_multiple_files = true; option java_package = "io.grpc.examples.helloworld"; option java_outer_classname = "HelloWorldProto"; option objc_class_prefix = "HLW"; package helloworld; // The greeting service definition. service Greeter { // Sends a greeting rpc SayHello (HelloRequest) returns (HelloReply) {} } // The request message containing the user's name. message HelloRequest { string name = 1; } // The response message containing the greetings message HelloReply { string message = 1; }
3.有了proto文件之后,还需要把proto文件编译成java源文件,现在需要在pom.xml文件中添加插件
<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>0.5.1</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> </configuration> <executions> <execution> <goals> <goal>compile</goal> <goal>compile-custom</goal> </goals> </execution> </executions> </plugin> </plugins> </build>
4.添加完成之后,执行mvn compile
这时就会在target/generated-sources目录下生成proto对应的java源文件
5.编写grpc服务,下面是服务端源代码
import io.grpc.Server; import io.grpc.ServerBuilder; import io.grpc.examples.helloworld.GreeterGrpc; import io.grpc.examples.helloworld.HelloReply; import io.grpc.examples.helloworld.HelloRequest; import io.grpc.stub.StreamObserver; import java.io.IOException; import java.util.logging.Logger; /** * Server that manages startup/shutdown of a {@code Greeter} server. */ public class HelloWorldServer { private static final Logger logger = Logger.getLogger(HelloWorldServer.class.getName()); private Server server; private void start() throws IOException { /* The port on which the server should run */ int port = 50051; server = ServerBuilder.forPort(port) .addService(new GreeterImpl()) .build() .start(); logger.info("Server started, listening on " + port); Runtime.getRuntime().addShutdownHook(new Thread() { @Override public void run() { // Use stderr here since the logger may have been reset by its JVM shutdown hook. 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(); } } /** * Await termination on the main thread since the grpc library uses daemon threads. */ private void blockUntilShutdown() throws InterruptedException { if (server != null) { server.awaitTermination(); } } /** * Main launches the server from the command line. */ public static void main(String[] args) throws IOException, InterruptedException { startServer(); } public static void startServer() throws IOException, InterruptedException { final HelloWorldServer server = new HelloWorldServer(); server.start(); server.blockUntilShutdown(); } static class GreeterImpl extends GreeterGrpc.GreeterImplBase { @Override public void sayHello(HelloRequest req, StreamObserver<HelloReply> responseObserver) { HelloReply reply = HelloReply.newBuilder().setMessage("Hello " + req.getName()).build(); responseObserver.onNext(reply); responseObserver.onCompleted(); } } }
6.再编写grpc客户端代码
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.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; public HelloWorldClient(String host, int port) { this(ManagedChannelBuilder.forAddress(host, port) .usePlaintext(true) .build()); } HelloWorldClient(ManagedChannel channel) { this.channel = channel; blockingStub = GreeterGrpc.newBlockingStub(channel); } public void shutdown() throws InterruptedException { channel.shutdown().awaitTermination(5, TimeUnit.SECONDS); } /** * 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 { response = blockingStub.sayHello(request); } catch (StatusRuntimeException e) { logger.log(Level.WARNING, "RPC failed: {0}", e.getStatus()); return; } logger.info("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 { start(); } public static void start() throws Exception { HelloWorldClient client = new HelloWorldClient("localhost", 50051); try { /* Access a service running on the local machine on port 50051 */ String user = "world"; client.greet(user); } finally { client.shutdown(); } } }
7.编写测试用例
public class Grpc { @Test public void startServer() throws Exception { HelloWorldServer.startServer(); } @Test public void startClient() throws Exception { HelloWorldClient.start(); } }
先执行startServer,再执行startClient这时就能看到grpc的调用了。