場景

gPRC簡介以及Java中使用gPRC實現客戶端與服務端通信(附代碼下載)：

https://blog.csdn.net/BADAO_LIUMANG_QIZHI/article/details/108711541

在上面的博客中介紹了gRPC以及使用最基本的rpc通信方式即一個請求對象返回一個響應的方式進行通信。

除此之外gRPC還有以下三種方式。

服務端流式

一個請求對象,服務端返回多個結果對象

proto示例語法

rpc GetStudentsByAge(StudentRequest) returns (stream StudentResponse) {}

客戶端流式

客戶端傳入多個請求對象，服務端返回一個響應結果。

proto示例語法

rpc GetStudentsWrapperByAges(stream StudentRequest) returns (StudentResponseList) {}

雙向流式

傳入多個對象可以返回多個響應對象

注：

博客：
https://blog.csdn.net/badao_liumang_qizhi
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實現

服務端流式實現

在上面博客的基礎上，打開Person.proto文件

message StudentRequest {int32 age = 1; }message StudentResponse {string name = 1;int32 age = 2;string city = 3; }

添加兩個message作為請求和響應對象。

因為gRPC的請求和響應對象必須在message中定義，不能直接使用string或者int32這種作為參數。

然后在新建接口方法

service PersonService {rpc GetStudentsByAge(StudentRequest) returns (stream StudentResponse) {} }

此方法是要請求參數為一個age，然后返回多個學生對象。

然后調用插件生成代碼。

然后來到PersonServiceImpl中對接口方法進行實現

??? @Overridepublic void getStudentsByAge(StudentRequest request, StreamObserver<StudentResponse> responseObserver) {System.out.println("接收到的客戶端消息為:"+request.getAge());responseObserver.onNext(StudentResponse.newBuilder().setName("1公眾號:霸道的程序猿").setAge(30).setCity("北京").build());responseObserver.onNext(StudentResponse.newBuilder().setName("2公眾號:霸道的程序猿").setAge(40).setCity("上海").build());responseObserver.onNext(StudentResponse.newBuilder().setName("3公眾號:霸道的程序猿").setAge(50).setCity("廣州").build());responseObserver.onCompleted();}

然后來到客戶端中

??????? ManagedChannel managedChannel? = ManagedChannelBuilder.forAddress("localhost",8899).usePlaintext().build();PersonServiceGrpc.PersonServiceBlockingStub blockingStub = PersonServiceGrpc.newBlockingStub(managedChannel);System.out.println("請求-流式響應，調用getRealNameByUsername");Iterator<StudentResponse> iter = blockingStub.getStudentsByAge(StudentRequest.newBuilder().setAge(20).build());while (iter.hasNext()){StudentResponse studentResponse = iter.next();System.out.println(studentResponse.getName());System.out.println(studentResponse.getAge());System.out.println(studentResponse.getCity());}

然后運行服務端后再運行客戶端

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此時服務端

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客戶端流式實現

打開proto文件

message StudentRequest {int32 age = 1; }message StudentResponse {string name = 1;int32 age = 2;string city = 3; }message StudentResponseList {repeated StudentResponse studentResponse = 1; }

添加響應的list，要實現客戶端發動流式多個請求參數(年齡)，服務端返回單個list對象，其中每個List的數據是學生對象。

添加接口方法

service PersonService {rpc GetStudentsWrapperByAges(stream StudentRequest) returns (StudentResponseList) {} }

然后調用插件生成代碼。打開PersonServiceImpl進行方法的實現

??? @Overridepublic StreamObserver<StudentRequest> getStudentsWrapperByAges(final StreamObserver<StudentResponseList> responseObserver) {return new StreamObserver<StudentRequest>() {public void onNext(StudentRequest studentRequest) {System.out.println("onNext:"+studentRequest.getAge());}public void onError(Throwable throwable) {System.out.println(throwable.getMessage());}public void onCompleted() {StudentResponse studentResponse = StudentResponse.newBuilder().setName("公眾號:霸道的程序猿").setAge(20).setCity("北京").build();StudentResponse studentResponse1 = StudentResponse.newBuilder().setName("1公眾號:霸道的程序猿").setAge(30).setCity("上海").build();StudentResponseList studentResponseList = StudentResponseList.newBuilder().addStudentResponse(studentResponse).addStudentResponse(studentResponse1).build();responseObserver.onNext(studentResponseList);responseObserver.onCompleted();}};}

與上面不同，客戶端如果是流式請求的話，那么客戶端必須使用異步的stub

PersonServiceGrpc.PersonServiceStub stub = PersonServiceGrpc.newStub(managedChannel);

客戶端代碼為

??????? ManagedChannel managedChannel? = ManagedChannelBuilder.forAddress("localhost",8899).usePlaintext().build();PersonServiceGrpc.PersonServiceStub stub = PersonServiceGrpc.newStub(managedChannel);System.out.println("-----------------------------");System.out.println("流式請求-響應，調用GetStudentsWrapperByAges");StreamObserver<StudentResponseList> studentResponseListStreamObserver = new StreamObserver<StudentResponseList>() {public void onNext(StudentResponseList studentResponseList) {studentResponseList.getStudentResponseList().forEach(studengResponse ->{System.out.println(studengResponse.getName());System.out.println(studengResponse.getAge());System.out.println(studengResponse.getCity());});}public void onError(Throwable throwable) {System.out.println(throwable.getMessage());}public void onCompleted() {System.out.println("completed");}};StreamObserver<StudentRequest> studentRequestStreamObserver = stub.getStudentsWrapperByAges(studentResponseListStreamObserver);studentRequestStreamObserver.onNext(StudentRequest.newBuilder().setAge(20).build());studentRequestStreamObserver.onNext(StudentRequest.newBuilder().setAge(30).build());studentRequestStreamObserver.onNext(StudentRequest.newBuilder().setAge(40).build());studentRequestStreamObserver.onCompleted();try {Thread.sleep(50000);} catch (InterruptedException e) {e.printStackTrace();}

因為是異步的所以必須使進程進行休眠才能看到效果

運行服務端后運行客戶端

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此時服務端

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雙向流式實現

打開proto文件

message StreamRequest {string request_info = 1; }message StreamResponse {string response_info = 1; }

新建流式請求與響應參數，然后新建接口方法

service PersonService {rpc BiTalk(stream StreamRequest) returns (stream StreamResponse) {} }

然后實現接口方法

??? @Overridepublic StreamObserver<StreamRequest> biTalk(StreamObserver<StreamResponse> responseObserver) {return new StreamObserver<StreamRequest>() {@Overridepublic void onNext(StreamRequest streamRequest) {System.out.println(streamRequest.getRequestInfo());responseObserver.onNext(StreamResponse.newBuilder().setResponseInfo(UUID.randomUUID().toString()).build());}@Overridepublic void onError(Throwable throwable) {System.out.println(throwable.getMessage());}@Overridepublic void onCompleted() {responseObserver.onCompleted();}};}

在客戶端中

package com.badao.grpcjava;import io.grpc.ManagedChannel; import io.grpc.ManagedChannelBuilder; import io.grpc.stub.StreamObserver;import java.time.LocalDate; import java.util.Iterator;public class GrpcClient {public static void main(String[] args) {ManagedChannel managedChannel? = ManagedChannelBuilder.forAddress("localhost",8899).usePlaintext().build();PersonServiceGrpc.PersonServiceStub stub = PersonServiceGrpc.newStub(managedChannel);System.out.println("-----------------------------");System.out.println("流式請求-流式響應，調用BiTalk");StreamObserver<StreamRequest> requestStreamObserver = stub.biTalk(new StreamObserver<StreamResponse>() {@Overridepublic void onNext(StreamResponse streamResponse) {System.out.println(streamResponse.getResponseInfo());}@Overridepublic void onError(Throwable throwable) {System.out.println(throwable.getMessage());}@Overridepublic void onCompleted() {System.out.println("onComplated");}});for(int i =0;i<10;i++){requestStreamObserver.onNext(StreamRequest.newBuilder().setRequestInfo(LocalDate.now().toString()).build());try {Thread.sleep(1000);} catch (InterruptedException e) {e.printStackTrace();}}try {Thread.sleep(50000);} catch (InterruptedException e) {e.printStackTrace();}} }

運行服務端后運行客戶端

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示例代碼下載

https://download.csdn.net/download/BADAO_LIUMANG_QIZHI/12883063

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