examples/android/helloworld/app/CMakeLists.txt

cmake_minimum_required(VERSION 3.4.1)

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")

set(helloworld_PROTOBUF_PROTOC_EXECUTABLE "/usr/local/bin/protoc" CACHE STRING "Protoc binary on host")
set(helloworld_GRPC_CPP_PLUGIN_EXECUTABLE "/usr/local/bin/grpc_cpp_plugin" CACHE STRING "gRPC CPP plugin binary on host")

set(GRPC_SRC_DIR ../../../../)

set(GRPC_BUILD_DIR ../grpc/outputs/${ANDROID_ABI})
file(MAKE_DIRECTORY ${GRPC_BUILD_DIR})

add_subdirectory(${GRPC_SRC_DIR} ${GRPC_BUILD_DIR})

set(GRPC_PROTO_GENS_DIR ${CMAKE_BINARY_DIR}/gens)
file(MAKE_DIRECTORY ${GRPC_PROTO_GENS_DIR})
include_directories(${GRPC_PROTO_GENS_DIR})

function(android_protobuf_grpc_generate_cpp SRC_FILES HDR_FILES INCLUDE_ROOT)
  if(NOT ARGN)
    message(SEND_ERROR "Error: android_protobuf_grpc_generate_cpp() called without any proto files")
    return()
  endif()

  set(${SRC_FILES})
  set(${HDR_FILES})
  set(PROTOBUF_INCLUDE_PATH -I ${INCLUDE_ROOT})
  foreach(FIL ${ARGN})
    get_filename_component(ABS_FIL ${FIL} ABSOLUTE)
    get_filename_component(FIL_WE ${FIL} NAME_WE)
    file(RELATIVE_PATH REL_FIL ${CMAKE_CURRENT_SOURCE_DIR}/${INCLUDE_ROOT} ${ABS_FIL})
    get_filename_component(REL_DIR ${REL_FIL} DIRECTORY)
    set(RELFIL_WE "${REL_DIR}/${FIL_WE}")

    list(APPEND ${SRC_FILES} "${GRPC_PROTO_GENS_DIR}/${RELFIL_WE}.pb.cc")
    list(APPEND ${HDR_FILES} "${GRPC_PROTO_GENS_DIR}/${RELFIL_WE}.pb.h")
    list(APPEND ${SRC_FILES} "${GRPC_PROTO_GENS_DIR}/${RELFIL_WE}.grpc.pb.cc")
    list(APPEND ${HDR_FILES} "${GRPC_PROTO_GENS_DIR}/${RELFIL_WE}.grpc.pb.h")

    add_custom_command(
      OUTPUT "${GRPC_PROTO_GENS_DIR}/${RELFIL_WE}.grpc.pb.cc"
             "${GRPC_PROTO_GENS_DIR}/${RELFIL_WE}.grpc.pb.h"
             "${GRPC_PROTO_GENS_DIR}/${RELFIL_WE}.pb.cc"
             "${GRPC_PROTO_GENS_DIR}/${RELFIL_WE}.pb.h"
      COMMAND ${helloworld_PROTOBUF_PROTOC_EXECUTABLE}
      ARGS --grpc_out=${GRPC_PROTO_GENS_DIR}
        --cpp_out=${GRPC_PROTO_GENS_DIR}
        --plugin=protoc-gen-grpc=${helloworld_GRPC_CPP_PLUGIN_EXECUTABLE}
        ${PROTOBUF_INCLUDE_PATH}
        ${REL_FIL}
      WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
      DEPENDS ${helloworld_PROTOBUF_PROTOC_EXECUTABLE} ${helloworld_GRPC_CPP_PLUGIN_EXECUTABLE} ${ABS_FIL} )
  endforeach()

  set_source_files_properties(${${SRC_FILES}} ${${HDR_FILES}} PROPERTIES GENERATED TRUE)
  set(${SRC_FILES} ${${SRC_FILES}} PARENT_SCOPE)
  set(${HDR_FILES} ${${HDR_FILES}} PARENT_SCOPE)
endfunction()

set(PROTO_BASE_DIR ${GRPC_SRC_DIR}/examples/protos)

android_protobuf_grpc_generate_cpp(
  HELLOWORLD_PROTO_SRCS HELLOWORLD_PROTO_HDRS ${PROTO_BASE_DIR} ${PROTO_BASE_DIR}/helloworld.proto)

add_library(helloworld_proto_lib
  SHARED ${HELLOWORLD_PROTO_HDRS} ${HELLOWORLD_PROTO_SRCS})

target_link_libraries(helloworld_proto_lib
  grpc++
  libprotobuf
  android
  log)

find_library(log-lib
 log)

add_library(grpc-helloworld
  SHARED src/main/cpp/grpc-helloworld.cc)

target_include_directories(grpc-helloworld
  PRIVATE ${HELLOWORLD_PROTO_HEADERS})

target_link_libraries(grpc-helloworld
  helloworld_proto_lib
  android
  ${log-lib})