#include <jni.h>
#include <stdio.h>

// 回调函数原型
void callback_from_java(JNIEnv *env, jobject obj, jint value) {
    printf("Received from Java: %d\n", value);
}

// 全局变量存储回调函数指针
void (*g_callback)(JNIEnv*, jobject, jint) = NULL;

// 注册回调函数
void register_callback(void (*callback)(JNIEnv*, jobject, jint)) {
    g_callback = callback;
}

public class DataSender {
    // 本地方法声明
    public native void sendDataToC(int data);
    
    // 加载本地库
    static {
        System.loadLibrary("DataSender");
    }
    
    // 供C调用的方法
    public static void receiveDataFromC(int data) {
        System.out.println("Received from C: " + data);
    }
}

#include "DataSender.h" // 由javah生成的头文件

JNIEXPORT void JNICALL Java_DataSender_sendDataToC(JNIEnv *env, jobject obj, jint data) {
    printf("Java is sending data: %d\n", data);
    
    // 如果有注册的回调函数，调用它
    if (g_callback != NULL) {
        g_callback(env, obj, data);
    }
}

#include <jni.h>

JavaVM *jvm;
JNIEnv *env;

void launchJVM() {
    JavaVMInitArgs vm_args;
    JavaVMOption options[1];
    
    options[0].optionString = "-Djava.class.path=."; // 设置类路径
    
    vm_args.version = JNI_VERSION_1_8;
    vm_args.nOptions = 1;
    vm_args.options = options;
    vm_args.ignoreUnrecognized = JNI_TRUE;
    
    // 创建JVM
    JNI_CreateJavaVM(&jvm, (void**)&env, &vm_args);
    
    // 注册回调
    register_callback(callback_from_java);
    
    // 查找并调用Java主类
    jclass cls = (*env)->FindClass(env, "DataSender");
    jmethodID mid = (*env)->GetStaticMethodID(env, cls, "main", "([Ljava/lang/String;)V");
    (*env)->CallStaticVoidMethod(env, cls, mid, NULL);
}

public class DataSender {
    public native void sendDataToC(int data);
    
    static {
        System.loadLibrary("DataSender");
    }
    
    public static void main(String[] args) {
        DataSender sender = new DataSender();
        
        // 模拟发送数据到C
        for (int i = 0; i < 5; i++) {
            sender.sendDataToC(i);
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
    
    public static void receiveDataFromC(int data) {
        System.out.println("Java received from C: " + data);
    }
}

#include <jni.h>
#include <stdio.h>

JavaVM *jvm;
JNIEnv *env;

void callback_from_java(JNIEnv *env, jobject obj, jint value) {
    printf("C received from Java: %d\n", value);
    
    // 可以在这里调用Java方法返回数据
    jclass cls = (*env)->GetObjectClass(env, obj);
    jmethodID mid = (*env)->GetStaticMethodID(env, cls, "receiveDataFromC", "(I)V");
    if (mid != NULL) {
        (*env)->CallStaticVoidMethod(env, cls, mid, value * 2);
    }
}

void (*g_callback)(JNIEnv*, jobject, jint) = NULL;

void register_callback(void (*callback)(JNIEnv*, jobject, jint)) {
    g_callback = callback;
}

JNIEXPORT void JNICALL Java_DataSender_sendDataToC(JNIEnv *env, jobject obj, jint data) {
    if (g_callback != NULL) {
        g_callback(env, obj, data);
    }
}

void launchJVM() {
    JavaVMInitArgs vm_args;
    JavaVMOption options[1];
    options[0].optionString = "-Djava.class.path=.";
    
    vm_args.version = JNI_VERSION_1_8;
    vm_args.nOptions = 1;
    vm_args.options = options;
    vm_args.ignoreUnrecognized = JNI_TRUE;
    
    JNI_CreateJavaVM(&jvm, (void**)&env, &vm_args);
    
    register_callback(callback_from_java);
    
    jclass cls = (*env)->FindClass(env, "DataSender");
    jmethodID mid = (*env)->GetStaticMethodID(env, cls, "main", "([Ljava/lang/String;)V");
    (*env)->CallStaticVoidMethod(env, cls, mid, NULL);
}

int main() {
    launchJVM();
    
    // 销毁JVM
    (*jvm)->DestroyJavaVM(jvm);
    return 0;
}