在上一篇的整體了解后,該篇則對應了快速上手,入門示例當然仍舊是Hello world,該一階段不需要深究代碼,所要求的的目的是先跑通,再回顧代碼,然后分析需要什么知識,再去學什么.

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1.Maven配置

首先是三個依賴包

<properties><grpc.version>1.0.3</grpc.version></properties><dependencies><dependency><groupId>io.grpc</groupId><artifactId>grpc-netty</artifactId><version>${grpc.version}</version></dependency><dependency><groupId>io.grpc</groupId><artifactId>grpc-protobuf</artifactId><version>${grpc.version}</version></dependency><dependency><groupId>io.grpc</groupId><artifactId>grpc-stub</artifactId><version>${grpc.version}</version></dependency></dependencies>

接著是轉換工具

<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:3.1.0:exe:${os.detected.classifier}</protocArtifact><pluginId>grpc-java</pluginId><pluginArtifact>io.grpc:protoc-gen-grpc-java:${grpc.version}:exe:${os.detected.classifier}</pluginArtifact></configuration><executions><execution><goals><goal>compile</goal><goal>compile-custom</goal></goals></execution></executions></plugin></plugins></build>

2.編寫proto文件

在main目錄下建立一個proto文件夾,然后在里面建立hello.proto,內容如下:

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 greetingrpc 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; }

接下來執行 mvn compile,就會生成如下代碼,如果未被標記為源代碼目錄的話,就右鍵標記下:

Paste_Image.png

3.編寫服務端代碼

public class HelloWorldServer {private int port = 50051;private Server server;/*** 啟動服務* @throws IOException*/private void start() throws IOException {server = ServerBuilder.forPort(port).addService(new GreeterImpl()).build().start();System.out.println("service start...");Runtime.getRuntime().addShutdownHook(new Thread() {@Overridepublic 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();}// 實現 定義一個實現服務接口的類private class GreeterImpl extends GreeterGrpc.GreeterImplBase {public void sayHello(HelloRequest req, StreamObserver<HelloReply> responseObserver) {//獲取參數System.out.println("收到的信息:"+req.getName());//這里可以放置具體業務處理代碼 start//這里可以放置具體業務處理代碼 end//構造返回HelloReply reply = HelloReply.newBuilder().setMessage(("Hello: " + req.getName())).build();responseObserver.onNext(reply);responseObserver.onCompleted();}} }

4.編寫客戶端代碼

public class HelloWorldClient {private final ManagedChannel channel; //一個gRPC信道private final GreeterGrpc.GreeterBlockingStub blockingStub;//阻塞/同步 存根//初始化信道和存根public HelloWorldClient(String host,int port){this(ManagedChannelBuilder.forAddress(host, port)// Channels are secure by default (via SSL/TLS). For the example we disable TLS to avoid// needing certificates..usePlaintext(true));}/** Construct client for accessing RouteGuide server using the existing channel. */private HelloWorldClient(ManagedChannelBuilder<?> channelBuilder) {channel = channelBuilder.build();blockingStub = GreeterGrpc.newBlockingStub(channel);}public void shutdown() throws InterruptedException {channel.shutdown().awaitTermination(5, TimeUnit.SECONDS);}//客戶端方法public void greet(String name){HelloRequest request = HelloRequest.newBuilder().setName(name).build();HelloReply response;try {response = blockingStub.sayHello(request);} catch (StatusRuntimeException e) {System.out.println("RPC調用失敗:"+e.getMessage());return;}System.out.println("服務器返回信息:"+response.getMessage());}public static void main(String[] args) throws InterruptedException {HelloWorldClient client = new HelloWorldClient("127.0.0.1",50051);try {for(int i=0;i<5;i++){client.greet("world:"+i);}}finally {client.shutdown();}} }

5.測試

服務端啟動后,客戶端訪問

客戶端:

Paste_Image.png

服務端:

Paste_Image.png

6.回顧分析

這一環節很重要,要對這個HelloWorld的Demo了解為什么跑通了.
回顧下在這個過程中做了哪些事情?
1.首先maven引入了三個依賴,分別是grpc-netty,grpc-protobuf,grpc-stub.應該是通訊,序列化,客戶端調用三部分的東西吧.最后在build里面引入了一堆東西.
2.寫proto文件,大概就是定義了一個服務接口的輸入輸出類型,然后利用build里面的工具,生成一堆代碼.

//指定proto3格式 syntax = "proto3"; //一些生成代碼的設置 option java_multiple_files = true; option java_package = "io.grpc.examples.helloworld"; option java_outer_classname = "HelloWorldProto"; option objc_class_prefix = "HLW";package helloworld;//定義了一個service service Greeter {rpc SayHello (HelloRequest) returns (HelloReply) {} }//定義了一個消息請求體 message HelloRequest {string name = 1; }//定義了一個消息回復體 message HelloReply {string message = 1; }

3.編寫服務端
服務端有如下代碼,可以看出這個接口和proto里面定義的接口是一致的.

private class GreeterImpl extends GreeterGrpc.GreeterImplBase{public void sayHello(HelloRequest req, StreamObserver<HelloReply> responseObserver) {}; }

然后使用如下代碼把該service綁定,

server = ServerBuilder.forPort(port).addService(new GreeterImpl()).build().start();

4.編寫客戶端代碼
客戶端通過如下方法創建了一個通信信道,然后和一個阻塞同步的通訊工具blockingStub.

//初始化信道和存根public HelloWorldClient(String host,int port){this(ManagedChannelBuilder.forAddress(host, port).usePlaintext(true));}private HelloWorldClient(ManagedChannelBuilder<?> channelBuilder) {channel = channelBuilder.build();blockingStub = GreeterGrpc.newBlockingStub(channel);}

然后通過該blockingStub調用服務端方法.

//客戶端方法public void greet(String name){HelloRequest request = HelloRequest.newBuilder().setName(name).build();HelloReply response;try {response = blockingStub.sayHello(request);} catch (StatusRuntimeException e) {System.out.println("RPC調用失敗:"+e.getMessage());return;}System.out.println("服務器返回信息:"+response.getMessage());}

接下來很自然的就去學proto3的一些相關知識了.

附錄:

相關代碼: https://github.com/nl101531/JavaWEB

作者：此博廢棄_更新在個人博客
鏈接：https://www.jianshu.com/p/46d600e5a1b1
來源：簡書

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