grpc使用客户端技巧

　　grpc 使用技巧，最近在做的项目是服务端是go语言提供服务使用的是grpc框架。

java在实现客户端的时候，参数的生成大部分采用创建者模式。java在接受go服务端

返回数据的时候，更多的是通过parseFrom形式来创建。

　　go 服务端 java 客户端 proto 文件要有些差异，见文章 https://learnku.com/articles/36922?order_by=created_at& 　　

　　demo样例：

　　

import com.google.protobuf.ByteString;
import com.google.protobuf.Descriptors;
import com.google.protobuf.InvalidProtocolBufferException;
import io.grpc.ManagedChannel;
import io.grpc.ManagedChannelBuilder;
import io.grpc.StatusRuntimeException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import pino.RequestInstance2;
import pino.grpc.routeguide.*;
import pino.pino_resp_pb;

import java.util.LinkedHashMap;
import java.util.Map;
import java.util.concurrent.TimeUnit;

/**
* Created  on 2017/5/4.
*/
public class PinoClient {

public static final RequestInstance2.FeatureGroup.Builder BUILDER_FEATURE = RequestInstance2.RequestInstance.newBuilder().getCommonFeature().toBuilder();
protected static final Logger logger = LoggerFactory.getLogger("file_logger");

private final ManagedChannel channel;
private final RouteGuideGrpc.RouteGuideBlockingStub blockingStub;

/** Construct client connecting to HelloWorld server at {@code host:port}. */
public PinoClient(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. */
PinoClient(ManagedChannelBuilder<?> channelBuilder) {
channel = channelBuilder.build();
blockingStub = RouteGuideGrpc.newBlockingStub(channel);
}

public void shutdown() throws InterruptedException {
channel.shutdown().awaitTermination(5, TimeUnit.SECONDS);
}

/** call pino to server. */
public Double callPino(double[] arr) {
if(logger.isInfoEnabled())
logger.info("start pino...");

if(arr==null)
return 0d;

RequestInstance2.Feature feature1 = RequestInstance2.RequestInstance.newBuilder()
.getCommonFeature().toBuilder().addFeaturesBuilder(0).setName("1").setSValue(String.valueOf(arr[0])).build();
RequestInstance2.Feature feature2 = RequestInstance2.RequestInstance.newBuilder()
.getCommonFeature().toBuilder().addFeaturesBuilder(0).setName("2").setSValue(String.valueOf(arr[1])).build();
RequestInstance2.Feature feature3 = RequestInstance2.RequestInstance.newBuilder()
.getCommonFeature().toBuilder().addFeaturesBuilder(0).setName("3").setSValue(String.valueOf(arr[2])).build();
RequestInstance2.Feature feature4 = RequestInstance2.RequestInstance.newBuilder()
.getCommonFeature().toBuilder().addFeaturesBuilder(0).setName("4").setSValue(String.valueOf(arr[3])).build();
RequestInstance2.Feature feature5 = RequestInstance2.RequestInstance.newBuilder()
.getCommonFeature().toBuilder().addFeaturesBuilder(0).setName("5").setSValue(String.valueOf(arr[4])).build();
RequestInstance2.Feature feature6 = RequestInstance2.RequestInstance.newBuilder()
.getCommonFeature().toBuilder().addFeaturesBuilder(0).setName("6").setSValue(String.valueOf(arr[5])).build();
RequestInstance2.Feature feature7 = RequestInstance2.RequestInstance.newBuilder()
.getCommonFeature().toBuilder().addFeaturesBuilder(0).setName("7").setSValue(String.valueOf(arr[6])).build();
RequestInstance2.Feature feature8 = RequestInstance2.RequestInstance.newBuilder()
.getCommonFeature().toBuilder().addFeaturesBuilder(0).setName("8").setSValue(String.valueOf(arr[7])).build();
RequestInstance2.Feature feature9 = RequestInstance2.RequestInstance.newBuilder()
.getCommonFeature().toBuilder().addFeaturesBuilder(0).setName("9").setSValue(String.valueOf(arr[8])).build();
RequestInstance2.Feature feature10 = RequestInstance2.RequestInstance.newBuilder()
.getCommonFeature().toBuilder().addFeaturesBuilder(0).setName("10").setSValue(String.valueOf(arr[9])).build();
RequestInstance2.Feature feature11 = RequestInstance2.RequestInstance.newBuilder()
.getCommonFeature().toBuilder().addFeaturesBuilder(0).setName("11").setSValue(String.valueOf(arr[10])).build();

RequestInstance2.RequestInstance.Builder builder = RequestInstance2.RequestInstance.newBuilder()
.addInstanceFeature(0, RequestInstance2.RequestInstance.newBuilder()
.getCommonFeature().toBuilder()
.addFeatures(0,feature1)
.addFeatures(1,feature2)
.addFeatures(2,feature3)
.addFeatures(3,feature4)
.addFeatures(4,feature5)
.addFeatures(5,feature6)
.addFeatures(6,feature7)
.addFeatures(7,feature8)
.addFeatures(8,feature9)
.addFeatures(9,feature10)
.addFeatures(10,feature11)
);

RequestInstance2.RequestInstance instance = builder.build();
byte[] bytes = instance.toByteArray();
ByteString bs = ByteString.copyFrom(bytes);

InputHead inputHead = InputHead.getDefaultInstance().toBuilder().setVersion(20).setBodySize(bs.size()).addAppKeys(0).setAppKeys(0, 85001).build();
Request request = Request.getDefaultInstance().toBuilder().setHead(inputHead).setBody(bs).build();

Response response = null;
try {
response = blockingStub.getPredictorValue(request);
} catch (StatusRuntimeException e) {
logger.error("RPC failed: "+ e.getStatus());
return 0d;
}
double value = 0d;
if(response!=null){

ByteString tempBytes = response.getBody();
try {
pino_resp_pb.Resp resp = pino_resp_pb.Resp.parseFrom(tempBytes);

if(resp.getOutputCount()>0){
pino_resp_pb.Output output = resp.getOutput(0);

pino_resp_pb.Matrix matrix = output.getMatrix();
if(matrix!=null&&matrix.getDoubleValCount()>0)
value = matrix.getDoubleVal(0);
}

System.out.println(value);
} catch (InvalidProtocolBufferException e) {
logger.error(e.getMessage(),e);
}
}

if(logger.isInfoEnabled())
logger.info("end pino.");
return value;
}

/**
* Greet server. If provided, the first element of {@code args} is the name to use in the
* greeting.
*/
public static void main(String[] args) throws Exception {
PinoClient client = new PinoClient("10.187.81.155", 80);

try {
/* Access a service running on the local machine on port 50051 */
String user = "world";
if (args.length > 0) {
user = args[0]; /* Use the arg as the name to greet if provided */
}
double[] features = {52.9186,4.2,0.0,0,0.03168337,8.771171,54.85312,0,0,0,0};
double[] features2 = {52.9186,4.2,0.0,0,0.03168337,8.771171,54.85312,0,0.03168337,8.771171,54.85312};
for(int i=0;i<10;i++){
client.callPino(features);
client.callPino(features2);
}
} finally {
client.shutdown();
}
}

}

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