Android Jni 创建多线程调用Java方法

一 .引入头文件 （注：不用添加 pthread.h 头文件）
二 . 贴上 C++ 代码
特别注意（pthread_create(&pt, NULL, runMethod, (void*)l); 会报红，不必理会

//当动态库被加载时这个函数被系统调用
JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM *vm, void *reserved)
{
JNIEnv* env = NULL;
jint result = -1;

 //获取JNI版本if (vm->GetEnv((void**)&env, JNI_VERSION_1_4) != JNI_OK) {     LOGD("GetEnv failed!");     return result; } return JNI_VERSION_1_4;

}

void* runMethod(void *args);

extern “C”
JNIEXPORT jint JNICALL
Java_opencv_ucsmy_com_jnithreadapplication_MainActivity_nativeThread(JNIEnv *env,
jobject instance) {
//保存全局JVM以便在子线程中使用
env->GetJavaVM(&g_jvm);
//不能直接赋值(g_obj = obj)
g_obj = env->NewGlobalRef(instance);

int l ;pthread_t pt ;//创建子线程//(pthread_t* _Nonnull, pthread_attr_t const*,void* (* _Nonnull start_routine)(void*), void*);pthread_create(&pt, NULL, runMethod, (void*)l);return 1;

}

void* runMethod(void *args) {

JNIEnv *env;jclass cls;jmethodID mid;//Attach主线程if(g_jvm->AttachCurrentThread(&env,args)!= JNI_OK){    LOGD("%s: AttachCurrentThread() failed", __FUNCTION__);    return NULL;}//找到对应的类cls = env->GetObjectClass(g_obj);if(cls == NULL){    LOGD("FindClass() Error.....");    return NULL;}//(jclass clazz, const char* name, const char* sig)jmethodID toastID = env->GetMethodID(cls,"showToast","()V");env->CallVoidMethod(g_obj,toastID);//Detach主线程if(g_jvm->DetachCurrentThread() != JNI_OK){    LOGD("%s: DetachCurrentThread() failed", __FUNCTION__);}pthread_exit(0);

}

三 ，贴上 Java 代码

public class MainActivity extends AppCompatActivity {

// Used to load the 'native-lib' library on application startup.static {    System.loadLibrary("native-lib");}@Overrideprotected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    // Example of a call to a native method    TextView tv = (TextView) findViewById(R.id.sample_text);    tv.setText("zsdtrhfaedrh");    nativeThread();}/** * A native method that is implemented by the 'native-lib' native library, * which is packaged with this application. */public native int nativeThread();public void showToast(){   final String name =  "我来自线程--》"+Thread.currentThread().getName();    runOnUiThread(new Runnable() {        @Override        public void run() {            Toast.makeText(MainActivity.this, name,                    Toast.LENGTH_SHORT).show();        }    });}

}