Xamarin.Android 引用so

  		[DllImport("sqleet", EntryPoint= "execute_test")]
        public static extern string execute_test(string path);
        //java
        [DllImport("native-lib", EntryPoint = "Java_com_km_demo_myapplication_MainActivity_stringFromJNI")]
        public extern static IntPtr stringFromJNI(IntPtr env, IntPtr thiz);
		//java
        [DllImport("hello", EntryPoint = "Java_com_km_demo_myapplication_hello_add")]  //省略掉lib前缀和.so 后缀
        //public static extern int add(IntPtr env, IntPtr thiz, int i, int j);
        [DllImport("hello")]  //省略掉lib前缀和.so 后缀
        public static extern int add( int i, int j);
        [DllImport("hello")]  //省略掉lib前缀和.so 后缀
        public static extern string getString(string str);

	//java 字符串
   var zz = stringFromJNI(System.IntPtr.Zero, System.IntPtr.Zero);
   Java.Lang.String ss = Java.Lang.Object.GetObject(zz, JniHandleOwnership.TransferLocalRef);
	//普通字符串
	string str = getString("abc");

java

#include 
#include 
extern "C" JNIEXPORT jstring JNICALL Java_com_km_demo_myapplication_MainActivity_stringFromJNI(
        JNIEnv* env,
        jobject ) {
    std::string hello = "Hello from C++";
    return env->NewStringUTF(hello.c_str());
}
//
// Created by Administrator on 2020/3/18.
//

#include 

#ifndef _Included_com_km_demo_myapplication_hello
#define _Included_com_km_demo_myapplication_hello
#ifdef __cplusplus
extern "C" {
#endif

JNIEXPORT jint JNICALL Java_com_km_demo_myapplication_hello_add
        (JNIEnv *, jobject, jint i, jint j){
    return i+j;
}
int add(int i, int j){
	return i+j;
}
#ifdef __cplusplus
}
#endif
#endif