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gRPC中Any类型的使用(Java和NodeJs端)

  工作中要把原来Java服务端基于SpringMVC的服务改为使用gRPC直接调用。由于原Service的返回值为动态的Map类型,key值不确定,且value的类型不唯一,因此使用了protobuf 3中的map和Any类型。在这个过程中遇到了一些困难,查阅资料时发现这一块的资料不是很多,尤其是在NodeJS的gRPC-Client处理google.protobuf.Any类型,完全找不到相关的资料。好在自己摸索和调试后解决了问题,因此记录下来以供他人之需。

 

testservice.proto:

 1 syntax = "proto3"; 2    3 import "google/protobuf/any.proto"; 4 option java_package = "com.zfp.demo.grpc"; 5    6 service TestService { 7    rpc getMapData (Param) returns (GenericMap); 8 } 9 10 message GenericMap {11     map<string, google.protobuf.Any> value = http://www.mamicode.com/1;12 }13 14 message Param{15     string value = http://www.mamicode.com/1;16 }17 18 message ListParam{19     repeated string value = http://www.mamicode.com/1;    20 }

  其中,Any类型的作用是在protobuf中不需要明确定义值的结构和类型,而是在gRPC的Server端通过pack()将任何message打包成Any类型(不可以直接打包Java Object),在client可以通过unPack()将message从Any中取出,实现了protobuf对泛型的支持。

 

Java Server:

 1 import com.google.protobuf.Any;
2 @Overried 3 public void getMapData(Testservice.Param request, StreamObserver<Testservice.GenericMap> responseObserver) { 4 5    Testservice.Param stringValue =http://www.mamicode.com/ Testservice.Param 6              .newBuilder() 7           .setValue("this is String type") 8              .build(); 9 10    List<String> tempList = Lists.newArrayList("this is", "List type");11    Testservice.ListParam listValue =http://www.mamicode.com/ Testservice.ListParam12           .newBuilder()13                 .addAllValue()14               .build();15 16    Map<String, Any> reMap = Maps.newHashMap();17    reMap.put("k1", Any.pack(stringValue));18    reMap.put("k2", Any.pack(listValue));19 20    Testservice.GenericMap genericMap = Testservice.GenericMap21                            .newBuilder()22                           .putAllValue(reMap)23                        .build();24 25    responseObserver.onNext(genericMap);26    responseObserver.onCompleted();27 }

 

Java Client:

 1 @Test 2 public void getMapDataTest() throws ExecutionException, InterruptedException { 3  4     ManagedChannel channel = ManagedChannelBuilder.forAddress("127.0.0.1", 6565) 5                           .usePlaintext(true) 6                             .build(); 7  8     TestServiceGrpc.RoomServiceBlockingStub bkStub = TestServiceGrpc.newBlockingStub(channel); 9 10 11     Testservice.Param param = Testservice.Param.newBuilder().setValue("test param").build();12 13     Map<String, Any> reMap = bkStub.getMapData(param).get().getValueMap();14 15     Map<String, Object> dataMap = Maps.newHashMap();16 17     reMap.forEach((k, v) -> {18             if (k.equals("k1")) {19                 try {20                     dataMap.put(k, v.unpack(Testservice.Param.class).getValue());21                 } catch (InvalidProtocolBufferException e) {22                     e.printStackTrace();23                 }24             } else {25                 try {26                     dataMap.put(k, v.unpack(Testservice.ListParam.class).getValueList());27                 } catch (InvalidProtocolBufferException e) {28                     e.printStackTrace();29                 }30             }31         });32 33         logger.info(JSON.toJSONString(dataMap, true));34     }

 

NodeJS Client:

var messages = require(‘./testservice_pb‘);var services = require(‘./testservice_grpc_pb‘); // 这两个文件是利用protoc命令根据 testservice.proto 自动生成的var grpc = require(‘grpc‘);var prob = require(‘./node_modules/google-protobuf/google/protobuf/any_pb‘);  // 使用了Any类型必须引入这个文件var jspb = require(‘google-protobuf‘);main = function () {    var client = new services.TestServiceClient(‘localhost:6565‘,        grpc.credentials.createInsecure());    var request = new messages.Param();    request.setValue("test param");    client.getMapData(request, function (err, res) {        var reMap = unPackGpMap(res);        console.log(reMap);    });};/** * 解包 google.protobuf.Any 对象,并返回结果 * @param {!google.protobuf.Any} gpAny */unPackAny = function (gpAny) {    var typeName = gpAny.getTypeName();  // 获取Any包装的message对象的类型名称    var deserialize;    switch (typeName) {        case "ListParam":            deserialize = messages.ListParam.deserializeBinary;  // 从Uint8Array反序列化ListParam的function            return unPackAny_List(gpAny, deserialize, typeName);        case "Param":            deserialize = messages.Param.deserializeBinary;            return unPackAny_OneField(gpAny, deserialize, typeName);        case "ObjParam":            deserialize = messages.ObjParam.deserializeBinary;            return unPackAny_ComplexObject(gpAny, deserialize, typeName);        default:            return "the Message type \‘" + typeName +                "\‘ is not defiend in .proto file";    }};

/**
* Any包装的message只含有一个名为value的字段时使用
*/unPackAny_OneField
= function (gpAny, deserialize, typeName) { return gpAny.unpack(deserialize, typeName).toObject()["value"];};/**
* Any包装的message含有一个名为value的repeated字段时使用
*/unPackAny_List
= function (gpAny, deserialize, typeName) { return gpAny.unpack(deserialize, typeName).toObject()["valueList"];};/**
* Any包装的message含有多个field时使用(message嵌套也同样适用)
*/unPackAny_ComplexObject
= function (gpAny, deserialize, typeName) { return gpAny.unpack(deserialize, typeName).toObject();};/** * 将 GenericMap 中需要的Map数据取出,并解包Any型的value, 组装成可读的reMap并返回 * @param gpMap * @returns {{}} */unPackGpMap = function (gpMap) { var dataMap = gpMap[‘wrappers_‘][‘1‘][‘map_‘]; var fieldList = Object.keys(dataMap); var reMap = {}; for (var i = 0; i < fieldList.length; i++) { reMap[fieldList[i]] = unPackAny(dataMap[fieldList[i]]["valueWrapper"]); } return reMap;};main();

 

  本文只展示了google.protobuf.Any的使用,Java和NodeJS中gRpc项目的具体构建可以参考以下项目:

  https://github.com/LogNet/grpc-spring-boot-starter

  https://github.com/grpc/grpc/tree/master/examples

gRPC中Any类型的使用(Java和NodeJs端)