上次简单介绍了grpc的使用方法，并创建了一个方法调用，在grpc中有四种服务类型，下面分别进行介绍
简单rpc
这就是一般的rpc调用，一个请求对象对应一个返回对象
proto语法：
rpc simpleHello(Person) returns (Result) {}
service代码
@Override
public void simpleHello(ProtoObj.Person request,
io.grpc.stub.StreamObserver<ProtoObj.Result> responseObserver) {
//返回结果
responseObserver.onNext(ProtoObj.Result.newBuilder().setString("hello, "+request.getMyName()).build());
responseObserver.onCompleted();
}
client代码
@Test
public void simple() throws InterruptedException {
final ManagedChannel channel = ManagedChannelBuilder.forAddress("127.0.0.1", 8080).usePlaintext(true).build();
//定义同步阻塞的stub
HelloServiceGrpc.HelloServiceBlockingStub blockingStub = HelloServiceGrpc.newBlockingStub(channel);
ProtoObj.Person person = ProtoObj.Person.newBuilder().setMyName("World").build();
//simple
System.out.println("---simple rpc---");
System.out.println(blockingStub.simpleHello(person).getString());
channel.shutdown();
}
输出
---simple rpc---
hello, World
服务端流式rpc
一个请求对象，服务端可以传回多个结果对象
proto语法
rpc serverStreamHello(Person) returns (stream Result) {}
service代码
@Override
public void serverStreamHello(ProtoObj.Person request,
io.grpc.stub.StreamObserver<ProtoObj.Result> responseObserver) {
//返回多个结果
responseObserver.onNext(ProtoObj.Result.newBuilder().setString("hello, "+request.getMyName()).build());
responseObserver.onNext(ProtoObj.Result.newBuilder().setString("hello2, "+request.getMyName()).build());
responseObserver.onNext(ProtoObj.Result.newBuilder().setString("hello3, "+request.getMyName()).build());
responseObserver.onCompleted();
}
client代码
@Test
public void serverStream(){
final ManagedChannel channel = ManagedChannelBuilder.forAddress("127.0.0.1", 8080).usePlaintext(true).build();
//定义同步阻塞的stub
HelloServiceGrpc.HelloServiceBlockingStub blockingStub = HelloServiceGrpc.newBlockingStub(channel);
ProtoObj.Person person = ProtoObj.Person.newBuilder().setMyName("World").build();
//server side
System.out.println("---server stream rpc---");
//返回结果是Iterator
Iterator<ProtoObj.Result> it = blockingStub.serverStreamHello(person);
while (it.hasNext()) {
System.out.print(it.next());
}
channel.shutdown();
}
输出
---server stream rpc---
string: "hello, World"
string: "hello2, World"
string: "hello3, World"
客户端流式rpc
客户端传入多个请求对象，服务端返回一个响应结果
proto语法
rpc clientStreamHello(stream Person) returns (Result) {}
service代码
@Override
public io.grpc.stub.StreamObserver<ProtoObj.Person> clientStreamHello(
final io.grpc.stub.StreamObserver<ProtoObj.Result> responseObserver) {
//返回observer应对多个请求对象
return new StreamObserver<ProtoObj.Person>(){
private ProtoObj.Result.Builder builder=ProtoObj.Result.newBuilder();
@Override
public void onNext(ProtoObj.Person value) {
builder.setString(builder.getString() +"," + value.getMyName());
}
@Override
public void onError(Throwable t) {
}
@Override
public void onCompleted() {
builder.setString("hello"+builder.getString());
responseObserver.onNext(builder.build());
responseObserver.onCompleted();
}
};
}
client代码
@Test
public void clientStream() throws InterruptedException {
final ManagedChannel channel = ManagedChannelBuilder.forAddress("127.0.0.1", 8080).usePlaintext(true).build();
//定义异步的stub
HelloServiceGrpc.HelloServiceStub asyncStub = HelloServiceGrpc.newStub(channel);
ProtoObj.Person person = ProtoObj.Person.newBuilder().setMyName("World").build();
//client side
System.out.println("---client stream rpc---");
StreamObserver<ProtoObj.Result> responseObserver = new StreamObserver<ProtoObj.Result>() {
@Override
public void onNext(ProtoObj.Result result) {
System.out.println("client stream--" + result.getString());
}
@Override
public void onError(Throwable t) {
}
@Override
public void onCompleted() {
//关闭channel
channel.shutdown();
}
};
StreamObserver<ProtoObj.Person> clientStreamObserver = asyncStub.clientStreamHello(responseObserver);
clientStreamObserver.onNext(ProtoObj.Person.newBuilder().setMyName("World").build());
clientStreamObserver.onNext(ProtoObj.Person.newBuilder().setMyName("World2").build());
clientStreamObserver.onCompleted();
//由于是异步获得结果，所以sleep一秒
Thread.sleep(1000);
}
输出
---client stream rpc---
client stream--hello,World,World2
双向流式rpc
结合客户端流式rpc和服务端流式rpc，可以传入多个对象，返回多个响应对象
proto语法
rpc biStreamHello(stream Person) returns (stream Result) {}
service代码
@Override
public io.grpc.stub.StreamObserver<ProtoObj.Person> biStreamHello(
final io.grpc.stub.StreamObserver<ProtoObj.Result> responseObserver) {
//返回observer应对多个请求对象
return new StreamObserver<ProtoObj.Person>(){
private ProtoObj.Result.Builder builder=ProtoObj.Result.newBuilder();
@Override
public void onNext(ProtoObj.Person value) {
responseObserver.onNext(ProtoObj.Result.newBuilder().setString("hello2, "+value.getMyName()).build());
responseObserver.onNext(ProtoObj.Result.newBuilder().setString("hello3, "+value.getMyName()).build());
}
@Override
public void onError(Throwable t) {
}
@Override
public void onCompleted() {
responseObserver.onCompleted();
}
};
}
client代码
@Test
public void bidirectStream() throws InterruptedException {
final ManagedChannel channel = ManagedChannelBuilder.forAddress("127.0.0.1", 8080).usePlaintext(true).build();
//定义异步的stub
HelloServiceGrpc.HelloServiceStub asyncStub = HelloServiceGrpc.newStub(channel);
ProtoObj.Person person = ProtoObj.Person.newBuilder().setMyName("World").build();
//bi stream
System.out.println("---bidirectional stream rpc---");
StreamObserver<ProtoObj.Result> responseObserver = new StreamObserver<ProtoObj.Result>() {
@Override
public void onNext(ProtoObj.Result result) {
System.out.println("bidirectional stream--"+result.getString());
}
@Override
public void onError(Throwable t) {
}
@Override
public void onCompleted() {
channel.shutdown();
}
};
StreamObserver<ProtoObj.Person> biStreamObserver=asyncStub.biStreamHello(responseObserver);
biStreamObserver.onNext(ProtoObj.Person.newBuilder().setMyName("World").build());
biStreamObserver.onNext(ProtoObj.Person.newBuilder().setMyName("World2").build());
biStreamObserver.onCompleted();
//由于是异步获得结果，所以sleep一秒
Thread.sleep(1000);
}
输出
---bidirectional stream rpc---
bidirectional stream--hello2, World
bidirectional stream--hello3, World
bidirectional stream--hello2, World2
bidirectional stream--hello3, World2
总结
grpc通过使用流式的方式，返回/接受多个实例可以用于类似不定长数组的入参和出参
