java grpc簡單例子

原文地址：http://blog.csdn.net/jek123456/article/details/53465033

用eclipse新建一個maven項目，Id信息以下

<groupId>com.mingluck.test</groupId> <artifactId>grpc</artifactId>

建立以下的目錄結構（包括文件） 
 
看下面的test.proto的內容：

syntax = "proto3"; package grpc; option java_package = "com.mingluck.grpc"; option java_outer_classname = "HelloWorldServiceProto"; option java_multiple_files = true; //服務端接口類 service Greeter { //服務端接口方法 rpc SayHello (HelloRequest) returns (HelloReply) {} } //請求參數 message HelloRequest { string name = 1; string sex = 2; } //響應參數 message HelloReply { string message = 1; }

 

其中java_package 指定了生成的類的包名 
pom.xml以下

<?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>com.mingluck.test</groupId> <artifactId>grpc</artifactId> <version>1.0-SNAPSHOT</version> <dependencies> <dependency> <groupId>io.grpc</groupId> <artifactId>grpc-all</artifactId> <version>1.0.0</version> </dependency> <dependency> <groupId>com.google.protobuf</groupId> <artifactId>protobuf-java</artifactId> <version>3.0.0</version> </dependency> <dependency> <groupId>org.apache.commons</groupId> <artifactId>commons-pool2</artifactId> <version>2.4.2</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> <!-- protobuf --> <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> <protoSourceRoot>src/main/resources/proto</protoSourceRoot> </configuration> <executions> <execution> <goals> <goal>compile</goal> <goal>compile-custom</goal> </goals> </execution> </executions> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <configuration> <source>1.8</source> <target>1.8</target> </configuration> </plugin> </plugins> </build> </project>

而後在cmd窗口中切換到項目pom.xml文件所在的目錄，運行mvn compile命令，運行命令後目錄結構會變成以下 
 
接下來能夠寫代碼了，先實現服務端程序，HelloWorldServer.java

package com.mingluck.grpc; /** * Created by Darren on 2016/11/11. */ import io.grpc.Server; import io.grpc.ServerBuilder; import io.grpc.stub.StreamObserver; import java.io.IOException; import java.util.concurrent.atomic.AtomicInteger; import java.util.logging.Logger; public class HelloWorldServer { private static final Logger logger = Logger.getLogger(HelloWorldServer.class.getName()); /* The port on which the server should run */ private int port = 50051; private Server server; private void start() throws IOException { server = ServerBuilder.forPort(port) .addService(GreeterGrpc.bindService(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 { final HelloWorldServer server = new HelloWorldServer(); server.start(); server.blockUntilShutdown(); } private class GreeterImpl implements GreeterGrpc.Greeter { /** 原子Integer */ public AtomicInteger count = new AtomicInteger(0); @Override public void sayHello(HelloRequest req, StreamObserver<HelloReply> responseObserver) { System.out.println("call sayHello"); HelloReply reply = HelloReply.newBuilder().setMessage("Hello " + req.getName() + req.getSex()).build(); responseObserver.onNext(reply); responseObserver.onCompleted(); System.out.println(count.incrementAndGet() + Thread.currentThread().getName()); } } } 

 

注意sayHello方法的重寫 
接下來實現HelloWorldClient.java

package com.mingluck.grpc; /** * Created by Darren on 2016/11/11. */ import io.grpc.ManagedChannel; import io.grpc.ManagedChannelBuilder; import io.grpc.StatusRuntimeException; import java.util.concurrent.TimeUnit; import java.util.logging.Level; import java.util.logging.Logger; /** * A simple client that requests a greeting from the {@link HelloWorldServer}. */ public class HelloWorldClient { private static final Logger logger = Logger.getLogger(HelloWorldClient.class.getName()); private final ManagedChannel channel; private final GreeterGrpc.GreeterBlockingStub blockingStub; /** Construct client connecting to HelloWorld server at {@code host:port}. */ 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); } /** Say hello to server. */ public void greet(String name) { logger.info("Will try to greet " + name + " ..."); HelloRequest request = HelloRequest.newBuilder().setName(name).setSex(" 女").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 { HelloWorldClient client = new HelloWorldClient("localhost", 50051); try { String user = "world"; if (args.length > 0) { user = args[0]; } client.greet(user); } finally { client.shutdown(); } } }

分別運行服務端和客戶端，會看到rpc調用成功。 
爲了防止客戶端不斷調用帶來的開銷(短鏈接)，下面的例子給出了鏈接池的方式，代碼以下

package com.mingluck.grpc; import org.apache.commons.pool2.BasePooledObjectFactory; import org.apache.commons.pool2.PooledObject; import org.apache.commons.pool2.impl.DefaultPooledObject; import org.apache.commons.pool2.impl.GenericObjectPool; import org.apache.commons.pool2.impl.GenericObjectPoolConfig; /** * Created by darren on 2016/11/14. */ public class HelloWorldClientFactory extends BasePooledObjectFactory<HelloWorldClient> { @Override public HelloWorldClient create() throws Exception { return new HelloWorldClient("localhost", 50051); } @Override public PooledObject<HelloWorldClient> wrap(HelloWorldClient client) { return new DefaultPooledObject<HelloWorldClient>(client); } @Override public void destroyObject(PooledObject<HelloWorldClient> p) throws Exception { HelloWorldClient client = p.getObject(); client.shutdown(); super.destroyObject(p); } public static void main(String[] args) throws Exception { /** 鏈接池的配置 */ GenericObjectPoolConfig poolConfig = new GenericObjectPoolConfig(); /** 下面的配置均爲默認配置,默認配置的參數能夠在BaseObjectPoolConfig中找到 */ poolConfig.setMaxTotal(8); // 池中的最大鏈接數 poolConfig.setMinIdle(0); // 最少的空閒鏈接數 poolConfig.setMaxIdle(8); // 最多的空閒鏈接數 poolConfig.setMaxWaitMillis(-1); // 當鏈接池資源耗盡時,調用者最大阻塞的時間,超時時拋出異常 單位:毫秒數 poolConfig.setLifo(true); // 鏈接池存放池化對象方式,true放在空閒隊列最前面,false放在空閒隊列最後 poolConfig.setMinEvictableIdleTimeMillis(1000L * 60L * 30L); // 鏈接空閒的最小時間,達到此值後空閒鏈接可能會被移除,默認即爲30分鐘 poolConfig.setBlockWhenExhausted(true); // 鏈接耗盡時是否阻塞,默認爲true /** 鏈接池建立 */ GenericObjectPool<HelloWorldClient> objectPool = new GenericObjectPool<HelloWorldClient>(new HelloWorldClientFactory(), poolConfig); new Thread(makeTask(objectPool)).start(); new Thread(makeTask(objectPool)).start(); new Thread(makeTask(objectPool)).start(); new Thread(makeTask(objectPool)).start(); Thread.sleep(100000); } private static Runnable makeTask(GenericObjectPool<HelloWorldClient> objectPool){ return () -> { HelloWorldClient client = null; try { client = objectPool.borrowObject(); } catch (Exception e) { e.printStackTrace(); } try { String req = "world!"; client.greet(req); } finally { /** 將鏈接對象返回給鏈接池 */ objectPool.returnObject(client); } }; } }