新建一个普通的Maven项目：
配置pom文件，导入gRPC的依赖和插件
pom 中增加外部依赖
<dependency>
<groupId>io.grpc</groupId>
<artifactId>grpc-all</artifactId>
<version>0.13.2</version>
</dependency>
注意，下面的增加 maven 插件： protobuf-maven-plugin: protobuf 的插件，不是 gRPC的插件，产生的代码只会是 protobuf 序列化、反序列化的代码，没有gRPC通讯部分的代码。
增加 maven 插件： protobuf-maven-plugin: 配置
<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>
<!--
The version of protoc must match protobuf-java. If you don't depend on
protobuf-java directly, you will be transitively depending on the
protobuf-java version that grpc depends on.
-->
<protocArtifact>com.google.protobuf:protoc:3.0.0-beta-2:exe:${os.detected.classifier}</protocArtifact>
<pluginId>grpc-java</pluginId>
<pluginArtifact>io.grpc:protoc-gen-grpc-java:0.13.2:exe:${os.detected.classifier}</pluginArtifact>
</configuration>
<executions>
<execution>
<goals>
<goal>compile</goal>
<goal>compile-custom</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
完整的 pom 文件如下：
<?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.ghj1976</groupId>
<artifactId>myGRPCDemo2</artifactId>
<version>1.0-SNAPSHOT</version>
<dependencies>
<dependency>
<groupId>io.grpc</groupId>
<artifactId>grpc-all</artifactId>
<version>0.13.2</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>
<!--
The version of protoc must match protobuf-java. If you don't depend on
protobuf-java directly, you will be transitively depending on the
protobuf-java version that grpc depends on.
-->
<protocArtifact>com.google.protobuf:protoc:3.0.0-beta-2:exe:${os.detected.classifier}</protocArtifact>
<pluginId>grpc-java</pluginId>
<pluginArtifact>io.grpc:protoc-gen-grpc-java:0.13.2:exe:${os.detected.classifier}</pluginArtifact>
</configuration>
<executions>
<execution>
<goals>
<goal>compile</goal>
<goal>compile-custom</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
编写 proto 文件，并编译产生对应的 java文件
简单期间这里直接用的 helloworld.proto 文件，内容如下：
// Copyright 2015, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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;
}
生成 protobuf 序列化和反序列化代码
注意，这里我们使用的maven 插件是 protobuf的插件，只能产生protobuf的序列化和反序列化的代码，不能产生gRPC通讯的代码。
如果我们只需要产生这部分代码是，才需要使用这个插件。
这个插件的用法参考下图：
如果用命令行生成，则命令是：
$ protoc --java_out=./java/ ./proto/helloworld.proto
生成 gRPC 通讯部分代码
这时候我们应该使用的是 protoc-gen-grpc-java插件。
这个插件的获取和编译方法请参考： http://www.cnblogs.com/ghj1976/p/5454881.html
我们这时候产生对应java代码的命令如下：
$ protoc --plugin=protoc-gen-grpc-java=/Users/ghj1976/project/github/grpc/grpc-java/compiler/build/exe/java_plugin/protoc-gen-grpc-java --grpc-java_out=./java/ ./proto/helloworld.proto
这两部生成的文件如下：
GreeterGrpc.java 是 protoc-gen-grpc-java 插件生成的， 其他文件时 protoc 生成的。
编写服务器端代码
我们服务器端的代码如下， 生成的文件在io.grpc.examples.helloworld， 我们的服务器端代码在 com.ghj1976 ：
package com.ghj1976;
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;
/**
* Created by ghj1976 on 16/5/4.
*/
public class HelloWorldServer {
private static final Logger logger = Logger.getLogger(HelloWorldServer.class.getName());
private int port = 50051;
private Server server;
private void start() throws IOException{
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(){
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 {
@Override
public void sayHello(HelloRequest req,StreamObserver<HelloReply> responseObserver){
HelloReply reply = HelloReply.newBuilder().setMessage(("Hello "+req.getName())).build();
responseObserver.onNext(reply);
responseObserver.onCompleted();
}
}
}
运行 这个类的 main 方法，就可以在 50051 端口启动服务。
go实现的服务器端代码在:
https://github.com/grpc/grpc-go/blob/master/examples/helloworld/greeter_server/main.go
编写客户端代码
为了实现跨语言的调用，我们可以用下面 go 实现的客户端来试验。
https://github.com/grpc/grpc-go/blob/master/examples/helloworld/greeter_client/main.go
如果用 Java 写客户端的话，则是下面代码：
package com.ghj1976;
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;
/**
* Created by ghj1976 on 16/5/4.
*/
public class HelloWorldClient {
private final ManagedChannel channel;
private final GreeterGrpc.GreeterBlockingStub blockingStub;
private static final Logger logger = Logger.getLogger(HelloWorldClient.class.getName());
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;
try{
response = blockingStub.sayHello(request);
} catch (StatusRuntimeException e)
{
logger.log(Level.WARNING, "RPC failed: {0}", e.getStatus());
return;
}
logger.info("Greeting: "+response.getMessage());
}
public static void main(String[] args) throws InterruptedException {
HelloWorldClient client = new HelloWorldClient("127.0.0.1",50051);
try{
String user = "world";
if (args.length > 0){
user = args[0];
}
client.greet(user);
}finally {
client.shutdown();
}
}
}
