一、Android平台Openmp配置

有两种方案：

1. cmake 配置

   app/CMakeLists.txt

   target_link_libraries( # Specifies the target library.
                      native-lib
   
                      -lgomp
   
                      # Links the target library to the log library
                      # included in the NDK.
                      ${log-lib} )
   

   app/build.gradle

   android {
   
        defaultConfig {
   	   ....
          externalNativeBuild {
              cmake {
            		   cppFlags "-fopenmp"
   	             cFlags "-fopenmp"
         	   }
      	   }
      	   ....
   	 }
   
        externalNativeBuild {
      	    cmake {
   		         path "CMakeLists.txt"
           }
   	 }
   }
   

2. ndk配置

   如果使用ndk方式生成Shared Library 需要把app/build.gradle 中的cmake相关配置注释。在*unix系统中，可以直接运行ndk-build/gen.sh 脚本。

   ...
   LOCAL_LDLIBS += -fopenmp
    LOCAL_CPPFLAGS += -fopenmp
    LOCAL_CFLAGS += -fopenmp
    LOCAL_LDFLAGS += -lgomp
   ...
   

二、C++中Openmp基本使用

JNICALL
Java_com_demon_omp_MainActivity_stringFromJNI(
        JNIEnv *env,
        jobject /* this */) {

    std::stringstream str_stream;
	 #pragma omp parallel 
    str_stream << '1'; //根据不同机型的最大线程数N，此句程序会执行N次

    std::string hello = str_stream.str();
    return env->NewStringUTF(hello.c_str());
}