NDK开发-3回调 返回java实例

native 实例化java类

public class Dog {
    public String name;
    public int age;

    public Dog(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public Dog(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        StringBuilder field2 = new StringBuilder();
        field2.append("[name： " + name);
        field2.append(";age： " + age + "]");
        return field2.toString();
    }


}
...
 public static native Dog getDog(String string);
  public static native Dog getDog2(String string,int t);
   log("getDog "+JniData.getDog("11"));
   log("getDog "+JniData.getDog2("22",3));

与上相似只是方法名用"<init>"

extern "C"
JNIEXPORT jobject JNICALL
Java_com_hrg_gys_clfr_myapplication_JniData_getDog(JNIEnv *env, jclass clazz, jstring string) {
    jclass jclass1 = env->FindClass("com/hrg/gys/clfr/myapplication/Dog"); //前没有L不以;号结束
    /* public Dog(String name)*/
    /*<init>构造方法不要写Dog了*/
    //    jmethodID jmethodId = env->GetMethodID(jclass1, "<init>", "(Ljava/lang/String;)V");
    //    jobject jobject1 = env->NewObject(jclass1, jmethodId, string);
    /*调用  public Dog(String name, int age) 构造方法*/
    jmethodID jmethodId = env->GetMethodID(jclass1, "<init>", "(Ljava/lang/String;I)V");
    jobject jobject1 = env->NewObject(jclass1, jmethodId, string, 2);
    return jobject1;
}

extern "C"
JNIEXPORT jobject JNICALL
Java_com_hrg_gys_clfr_myapplication_JniData_getDog2(JNIEnv *env, jclass clazz, jstring string,
                                                    jint t) {
    // TODO: implement getDog2()
    jclass jclass1 = env->FindClass("com/hrg/gys/clfr/myapplication/Dog"); //前没有L不以;号结束
    jmethodID jmethodId = env->GetMethodID(jclass1, "<init>", "(Ljava/lang/String;I)V");
 /*创建类 再调用类的构造方法*/
    jobject jobject1 = env->AllocObject(jclass1);
  /*调用了类的构造方法*/
    env->CallNonvirtualVoidMethod(jobject1,jclass1,jmethodId,string,t);
    return jobject1;
}

等待native的加调

public class JniInvokeMethod {
    static {
        System.loadLibrary("native-lib");
    }
    public native void  nativeCallback(CallBack callBack);
    public native void  nativeThreadCallback(CallBack callBack);

    public interface  CallBack{
        void doBack();
    }
}

...
               new  JniInvokeMethod().nativeCallback(new JniInvokeMethod.CallBack() {
                   @Override
                   public void doBack() {
                       log("JniInvokeMethod nativeCallback " + Thread.currentThread().getName());
                   }
               });
               new  JniInvokeMethod().nativeThreadCallback(new JniInvokeMethod.CallBack() {
                   @Override
                   public void doBack() {
                       log("JniInvokeMethod nativeThreadCallback " + Thread.currentThread().getName());
                   }
               });

原理很简单 找到方法执行与 参考 NDK开发-2-数据交换

extern "C"
JNIEXPORT void JNICALL
**_nativeCallback(JNIEnv *env, jobject thiz,
                                                                   jobject call_back) {
    jclass jclass1 = env->GetObjectClass(call_back);
    jmethodID jmethodId = env->GetMethodID(jclass1, "doBack", "()V");
    env->CallVoidMethod(call_back, jmethodId);
}

异步回调

JavaVM *g_VM;
jobject threadObject;


void *threadCallback(void *) {
// env 不能跨线程 子线程中运行的
    JNIEnv *env;
    if(g_VM->AttachCurrentThread(&env, NULL)==0){
        /*找到方法回调*/
        jclass threadClass = env->GetObjectClass(threadObject);
        jmethodID threadMethod = env->GetMethodID(threadClass, "doBack", "()V");
        env->CallVoidMethod(threadObject, threadMethod);
        /*AttachCurrentThread成对使用*/
        g_VM->DetachCurrentThread();
    }
    return 0;
}

extern "C"
JNIEXPORT void JNICALL
***nativeThreadCallback(JNIEnv *env, jobject thiz,
                                                                         jobject call_back) {
    env->GetJavaVM(&g_VM); /*保存env对象*/
    threadObject = env->NewGlobalRef(call_back); /*创建全局的对象，否则子线程是找不到的*/
    pthread_t handle;
    pthread_create(&handle, NULL, threadCallback, NULL);
}


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