JNI实现回调| JNI调用JAVA函数|参数和返回值的格式

一、JNI实现回调

通过JNI在Native层调用JAVA层的方法，来实现Native层向JAVA层传递消息。

JNICallback.java

 public class JNICallback extends Activity {
     static {
         System.loadLibrary("callback");
     }
     public void callback(int notify_id, int param)
     {
         Log.e("JNICallback","notify_id="+notify_id+";param="+param);
     }
     public native void setCallBack();

     /** Called when the activity is first created. */
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.main);
         setCallBack();
     }
 <span style="font-family:Comic Sans MS;">}</span>

com_JNICallback_JNICallback.cpp

 void JNICALL Java_com_JNICallback_JNICallback_setCallBack
   (JNIEnv *env, jobject obj)
 {
     LOGE("jni callback (0)");
     jclass cls = env->GetObjectClass(obj);
     jmethodID callback = env->GetMethodID(cls,"callback","(II)V");
     env->CallVoidMethod(obj,callback,5,10);
     LOGE("jni callback (1)");
 }

javah -classpath . -jni com.JNICallback.JNICallback（包名+类名）

 

二、JNI调用JAVA函数

获取实例的类定义 jclass cls = env->GetObjectClass(obj);

获取方法定义  jmethodID callback = env->GetMethodID(cls,"callback","(II)V");

调用方法 env->CallVoidMethod(obj,callback,5,10);

三、参数和返回值的格式