JNI实现回调| JNI调用JAVA函数|参数和返回值的格式

代码下载：http://dl.dbank.com/c0c0xs3b24

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();
    }
}

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

参考 http://java.sun.com/docs/books/jni/html/jniTOC.html