java 接口定义：

public interface Callback {void onResult(int status, String message);
}

java 设置回调：

public class Sample {static {System.loadLibrary("sample_core_jni");}public static native int process(long handle, String message);public static void onCallback(int status, String message) {if (mCallback != null) {mCallback.onResult(status, message);}}private static Callback mCallback;public static void setCallback(Callback callback) {if (callback == null) {throw new NullPointerException("callback can not be null");}mCallback = callback;}// 添加其他native函数
....
}

JNI 注册回调函数：

#include <jni.h>
#include <iostream>// 全局引用，确保JNI环境可以访问
JavaVM *g_VM;
jclass gCallbackClassSample = nullptr;
jmethodID gOnCallbackMethodID = nullptr;JNIEXPORT jint JNI_OnLoad(JavaVM *vm, void *reserved) {JNIEnv *env = nullptr;jint result = -1;if (vm->GetEnv((void **) &env, JNI_VERSION_1_6) != JNI_OK) {return result;}//JavaVM是虚拟机在JNI中的表示，等下再其他线程回调java层需要用到env->GetJavaVM(&g_VM);register_fields(env);LOGI("JNI OnLoad result : %d", result);return JNI_VERSION_1_6;
}register_fields(JNIEnv *env) {//注册Java回调函数所在的类及回调函数
}int ChatCallback(int status, const char *output) {JNIEnv *env;bool mNeedDetach = false;//获取当前native线程是否有没有被附加到jvm环境中int getEnvStat = (*g_VM).GetEnv( (void **)&env, JNI_VERSION_1_6);if (getEnvStat == JNI_EDETACHED) {//如果没有， 主动附加到jvm环境中，获取到envif (g_VM->AttachCurrentThread(&env, NULL) != JNI_OK) {LOGE("ChatCallback failed to attach current thread");}mNeedDetach = JNI_TRUE;}jString j_out = native_message_to_java_message(env, output);if (fields.chat_result_callback != nullptr) {env->CallStaticVoidMethod(gCallbackClassSample, gOnCallbackMethodID, (int)status, j_out);}//释放当前线程if(mNeedDetach) {g_VM->DetachCurrentThread();}env = NULL;return 0;
}extern "C"
JNIEXPORT void JNICALL
Java_com_example_yourapp_process(JNIEnv *env, jlong handle, jString message) {//const char* c_message = ...//该函数为异步函数int err = Chat(handle, c_message, ChatCallback);
}