1.定义消息格式
在 src/main/proto 目录下创建 person.proto 文件，并定义消息格式，例如：
syntax = "proto3";
package example;
message Person {
string name = 1;
int32 age = 2;
repeated string interests = 3;
}这个文件定义了一个名为 Person 的消息类型，包括三个字段：name、age 和 interests
2.生成代码
使用 protoc 工具来生成 Java 代码，需要安装相应的插件和工具，可以通过 Maven 或 Gradle 等构建工具自动下载和配置。这里演示手动下载和安装的方式。
首先下载 protoc 工具及其插件，例如从官方网站下载对应版本的 protoc-3.x.x-linux-x86_64.zip，以及 protoc-gen-grpc-java 插件，例如从 Maven 中央仓库下载最新版的 protoc-gen-grpc-java-1.42.0-linux-x86_64.exe。
然后解压 protoc 工具，将 protoc 命令所在的路径添加到环境变量 PATH 中，例如：
export PATH="/path/to/protoc/bin:$PATH"接下来安装 protobuf-java 和 grpc-java 两个依赖，例如通过 Maven 引入以下依赖：
<dependency>
<groupId>com.google.protobuf</groupId>
<artifactId>protobuf-java</artifactId>
<version>3.17.3</version>
</dependency>
<dependency>
<groupId>io.grpc</groupId>
<artifactId>grpc-netty-shaded</artifactId>
<version>1.42.0</version>
</dependency>
<dependency>
<groupId>io.grpc</groupId>
<artifactId>grpc-protobuf</artifactId>
<version>1.42.0</version>
</dependency>
<dependency>
<groupId>io.grpc</groupId>
<artifactId>grpc-stub</artifactId>
<version>1.42.0</version>
</dependency>
<dependency>
<groupId>io.grpc</groupId>
<artifactId>grpc-testing</artifactId>
<version>1.42.0</version>
<scope>test</scope>
</dependency>接着使用 protoc 生成 Java 代码，例如：
protoc --java_out=src/main/java --grpc-java_out=src/main/java src/main/proto/person.proto这个命令会在 src/main/java/example 目录下生成 Person.java、PersonGrpc.java 和 PersonGrpc$PersonStub.java 等文件。
3.实现服务端
package example;
import io.grpc.Server;
import io.grpc.ServerBuilder;
import io.grpc.stub.StreamObserver;
import java.io.IOException;
public class PersonServer {
private final int port;
private final Server server;
public PersonServer(int port) throws IOException {
this.port = port;
this.server = ServerBuilder.forPort(port)
.addService(new PersonServiceImpl())
.build();
}
public void start() throws IOException {
server.start();
System.out.println("Server started, listening on " + port);
Runtime.getRuntime().addShutdownHook(new Thread(() -> {
System.err.println("*** shutting down gRPC server since JVM is shutting down");
PersonServer.this.stop();
System.err.println("*** server shut down");
}));
}
public void stop() {
if (server != null) {
server.shutdown();
}
}
private static class PersonServiceImpl extends PersonGrpc.PersonImplBase {
@Override
public void getMessage(PersonRequest request, StreamObserver<PersonResponse> responseObserver) {
String name = request.getName();
int age = request.getAge();
String interests = String.join(", ", request.getInterestsList());
// 将请求的内容响应回去
PersonResponse response = PersonResponse.newBuilder()
.setMessage("Received person info: name=" + name + ", age=" + age + ", interests=[" + interests + "]")
.build();
responseObserver.onNext(response);
responseObserver.onCompleted();
}
}
public static void main(String[] args) throws IOException, InterruptedException {
PersonServer server = new PersonServer(8989);
server.start();
server.blockUntilShutdown();
}
}
4.实现客户端
package example;
import io.grpc.ManagedChannel;
import io.grpc.ManagedChannelBuilder;
import io.grpc.stub.StreamObserver;
import java.util.Arrays;
import java.util.List;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
public class PersonClient {
private final ManagedChannel channel;
private final PersonGrpc.PersonStub stub;
public PersonClient(String host, int port) {
this.channel = ManagedChannelBuilder.forAddress(host, port)
.usePlaintext()
.build();
this.stub = PersonGrpc.newStub(channel);
}
public void shutdown() throws InterruptedException {
channel.shutdown().awaitTermination(5, TimeUnit.SECONDS);
}
public void sendMessage(String name, int age, String... interests) throws InterruptedException {
final CountDownLatch latch = new CountDownLatch(1);
StreamObserver<PersonResponse> responseObserver = new StreamObserver<PersonResponse>() {
@Override
public void onNext(PersonResponse response) {
System.out.println("Received response: " + response.getMessage());
}
@Override
public void onError(Throwable t) {
System.err.println("Received error: " + t.getMessage());
latch.countDown();
}
@Override
public void onCompleted() {
System.out.println("Request completed");
latch.countDown();
}
};
List<String> interestList = Arrays.asList(interests);
PersonRequest request = PersonRequest.newBuilder()
.setName(name)
.setAge(age)
.addAllInterests(interestList)
.build();
stub.getMessage(request, responseObserver);
latch.await();
}
public static void main(String[] args) throws InterruptedException {
PersonClient client = new PersonClient("localhost", 8989);
// 向服务器发送请求
client.sendMessage("Alice", 20, "reading", "swimming");
// 关闭连接
client.shutdown();
}
}这个客户端会向服务器发送一个包含 name、age 和 interests 字段的 PersonRequest 消息，并等待接收服务器的响应信息。
