手写 JNI 线程

MyThread.java

public class MyThread {
    static {
        // 加载全路径名
        System.load("/root/lib/libMyThreadNative.so");
        // 加载环境变量
        // System.loadLibrary("libMyThreadNative");
    }
    public static void main(String[] args) {
        MyThread myThread = new MyThread();
        myThread.start();
    }
    public void start() {
        start0();
    }
    // javah MyThread
    private native void start0();
}

MyThread.h

/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class org_example_se_concurrency_thread_MyThread */
#ifndef _Included_org_example_se_concurrency_thread_MyThread
#define _Included_org_example_se_concurrency_thread_MyThread
#ifdef __cplusplus
extern "C" {
#endif
/*
 * Class:     org_example_se_concurrency_thread_MyThread
 * Method:    start0
 * Signature: ()V
 */
JNIEXPORT void JNICALL Java_MyThread_start0
  (JNIEnv *, jobject);
#ifdef __cplusplus
}
#endif
#endif

MyThread.c

#include <stdio.h>
#include <unistd.h>
#include <pthread.h>
#include <MyThread.h>
using namespace std;
pthread_t pid; // 定义变量，接收创建后的线程 ID
void *java_start(void *args) {
    while (1) {
        usleep(1000 * 1000); // 单位是微秒
        printf("this is java_start method\n");
    }
}
JNIEXPORT void JNICALL Java_MyThread_start0(JNIEnv *env, jobject obj) {
    pthread_create(&pid, NULL, java_start, NULL);
    while (1) {
        usleep(1000 * 1000); // 单位是微秒
        printf("this is start0 method\n");
    }
}
// gcc my_thread.cpp -o my_thread.out -pthread
// ./my_thread.out
int main() {
    pthread_create(&pid, NULL, java_start, NULL);
    while (1) {
        usleep(1000 * 1000); // 单位是微秒
        printf("this is start0 method\n");
    }
    return 0;
}

GCC 编译

gcc -fPIC -I /usr/local/jdk1.8.0_261/include -I /usr/local/jdk1.8.0_261/include/linux -shared -o libMyThreadNative.so my_thread.cpp -pthread

调用

java MyThread