kotlin android的gRPC：导入“google/protobuf/wrappers.proto”不起作用

Question

我在https://github.com/grpc/grpc-java/tree/master/examples/example-kotlin/android/helloworld创建了一个gRPC项目，非常类似于kotlin android项目的示例gRPC

如果我使用示例proto文件，构建过程就会正常工作。但现在，我已经用不同的原始文件替换了这些原始文件，Gradle无法构建我的项目。

这是失败的原型文件：

syntax = "proto3";

package tensorflow.serving;
option cc_enable_arenas = true;

import "google/protobuf/wrappers.proto";

// Metadata for an inference request such as the model name and version.
message ModelSpec {
  // Required servable name.
  string name = 1;

  // Optional version.
  google.protobuf.Int64Value version = 2;

  // A named signature to evaluate. If unspecified, the default signature will
  // be used.
  string signature_name = 3;
}

错误消息为：

  Cause: protoc: stdout: . stderr: app/build/extracted-include-protos/main: warning: directory does not exist.
  app/build/extracted-include-protos/main: warning: directory does not exist.
  app/src/debug/proto: warning: directory does not exist.
  app/src/debug/proto: warning: directory does not exist.
  google/protobuf/wrappers.proto: File not found.
  model.proto: Import "google/protobuf/wrappers.proto" was not found or had errors.
  model.proto:30:3: "google.protobuf.Int64Value" is not defined.

Answer 1

普通protobuf jar附带的“知名”protos不包含在protobuf-lite jar中，kotlin Android示例正在使用该jar。已在中跟踪问题https://github.com/protocolbuffers/protobuf/issues/1889

作为一种解决方法，您可以将普通protobuf jar中的protos添加到您的项目中：

dependencies {
  protobuf 'com.google.protobuf:protobuf-java:3.5.1'
}