java grpc简单例子

素颜马尾好姑娘i 2021-06-11 15:12 546阅读 0赞

用eclipse新建一个maven项目，Id信息如下

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

创建如下的目录结构（包括文件）   
![grpc][]   
看下面的test.proto的内容：

syntax = "proto3";
    package grpc;
    option java_package = "com.mingluck.grpc";
    option java_outer_classname = "HelloWorldServiceProto";
    option java_multiple_files = true;
    
    //服务端接口类
    service Greeter {
      //服务端接口方法
      rpc SayHello (HelloRequest) returns (HelloReply) {}
    }
    
    //请求参数
    message HelloRequest {
      string name = 1;
      string sex = 2;
    }
    
    //响应参数
    message HelloReply {
      string message = 1;
    }

其中java\_package 指定了生成的类的包名   
pom.xml如下

<?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>
                
                <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>

然后在cmd窗口中切换到项目pom.xml文件所在的目录，运行mvn compile命令，运行命令后目录结构会变成如下   
![grpc][grpc 1]   
接下来可以写代码了，先实现服务端程序，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方法的重写   
接下来实现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();
            }
        }
    }

分别运行服务端和客户端，会看到rpc调用成功。   
为了防止客户端不断调用带来的开销(短连接)，下面的例子给出了连接池的方式，代码如下

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 {
    
            /** 连接池的配置 */
            GenericObjectPoolConfig poolConfig = new GenericObjectPoolConfig();
    
            /** 下面的配置均为默认配置,默认配置的参数可以在BaseObjectPoolConfig中找到 */
            poolConfig.setMaxTotal(8); // 池中的最大连接数
            poolConfig.setMinIdle(0); // 最少的空闲连接数
            poolConfig.setMaxIdle(8); // 最多的空闲连接数
            poolConfig.setMaxWaitMillis(-1); // 当连接池资源耗尽时,调用者最大阻塞的时间,超时时抛出异常 单位:毫秒数
            poolConfig.setLifo(true); // 连接池存放池化对象方式,true放在空闲队列最前面,false放在空闲队列最后
            poolConfig.setMinEvictableIdleTimeMillis(1000L * 60L * 30L); // 连接空闲的最小时间,达到此值后空闲连接可能会被移除,默认即为30分钟
            poolConfig.setBlockWhenExhausted(true); // 连接耗尽时是否阻塞,默认为true
    
            /** 连接池创建 */
            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 {
                    /** 将连接对象返回给连接池 */
                   objectPool.returnObject(client);
                }
            };
        }
    }

[grpc]: /images/20210527/ad5b0714ff464791bb8c581fc8d30da3.png
[grpc 1]: /images/20210527/dbfe15f8e5b3401ba9cd391aba0268b5.png