Protobuf gRPC - google protobuf package 不存在

Question

I am trying to implement gRPC and now I'm having all sorts of issues, but I just don't get what I'm doing wrong. I am following this doc: https://github.com/grpc/grpc-java/blob/master/README.md

And now I keep getting such errors when I'm trying to build my project

error: package com.google.protobuf.GeneratedMessageV3 does not exist
com.google.protobuf.GeneratedMessageV3.Builder<Builder> implements

In my Android Studio external libraries I have protobuf-java-3.12.1 jar .

In my project gradle file I've added this to dependencies:

classpath 'com.google.protobuf:protobuf-gradle-plugin:0.8.14'

And in my app gradle file:

apply plugin: 'com.android.application'
apply plugin: 'com.google.protobuf'

In dependencies I added:

implementation 'io.grpc:grpc-okhttp:1.35.0'
implementation 'io.grpc:grpc-protobuf-lite:1.35.0'
implementation 'io.grpc:grpc-stub:1.35.0'
compileOnly 'org.apache.tomcat:annotations-api:6.0.53'
implementation 'com.google.protobuf:protobuf-javalite:3.12.1'

And outside of the android tag:

protobuf {
    protoc {
        artifact = "com.google.protobuf:protoc:3.12.1"
    }
    plugins {
        grpc {
            artifact = 'io.grpc:protoc-gen-grpc-java:1.35.0'
        }
    }
    generateProtoTasks {
        all()*.plugins {
            grpc {}
        }
    }
}

Finally, my proto file:

syntax = "proto3";
import "google/protobuf/timestamp.proto"; 
option java_package = "com.xxx.xxx.proto.log";
option java_outer_classname = "MyClass";

message MyObject {
    string name = 1;
    string unit = 2;

    oneof value {
         bool bool_value = 3;
         sint32 int32_value = 4;
         uint32 u_int32_value = 5;
         google.protobuf.Timestamp timestamp_value = 6;
    }
}   

When I run: protoc --version in terminal, this is the output:

libprotoc 3.12.1

Do I have to add something else or I missed something in my Gradle setup?

Answer 1

It looks like you are hoping to use protobuf lite (as is normal for Android projects):

implementation 'io.grpc:grpc-protobuf-lite:1.35.0'
...
implementation 'com.google.protobuf:protobuf-javalite:3.12.1'

However, currently you are generating full protobuf code. You need to tell the java and grpc-java code generators to generate for lite via options. As seen in the grpc-java Android helloworld example :

protobuf {
    ...
    generateProtoTasks {
        all().each { task ->
            task.builtins {
                java { option 'lite' }
            }
            task.plugins {
                grpc { option 'lite' }
            }
        }
    }
}