[英]Android Native Activity - Call Java method
我已經嘗試了一段時間,從c ++調用java方法,我能夠使用Activity類成功完成此操作,但是使用NativeActivity,調用CallVoidMethod時崩潰。 GetMethodID能夠找到它,它返回一個地址。 env和vm對象有效,並從android_main()填充。 是否有可能根本無法與本機活動類一起使用?
Cpp :(已編輯)
void SendNotification() {
JavaVM* lJavaVM = main_activity->vm;
JNIEnv* lJNIEnv = main_activity->env;
JavaVMAttachArgs lJavaVMAttachArgs;
lJavaVMAttachArgs.version = JNI_VERSION_1_6;
lJavaVMAttachArgs.name = "NativeThread";
lJavaVMAttachArgs.group = NULL;
jint lResult = lJavaVM->AttachCurrentThread(&lJNIEnv, &lJavaVMAttachArgs);
if (lResult == JNI_ERR)
return;
jobject lNativeActivity = main_activity->clazz;
jclass ClassNativeActivity = lJNIEnv->GetObjectClass(main_activity->clazz);
jmethodID _method = lJNIEnv->GetMethodID(ClassNativeActivity, "SendNotification", "()V");
lJNIEnv->CallVoidMethod(lNativeActivity, _method);
lJavaVM->DetachCurrentThread();
}
Java的:
package com.thor.kalen;
import android.app.AlertDialog;
import android.app.NativeActivity;
import android.os.Bundle;
public class MainActivity extends NativeActivity
{
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
} // End of public void onCreate(Bundle savedInstanceState)
public void SendNotification() {
new AlertDialog.Builder(this).setTitle("Alert").setMessage("").setNeutralButton("Close", null).show();
}
}
com.thor.kalen.MainActivity.SendNotification()應該為com.thor.kalen.MainActivity類的jobject調用Java方法,而不是該對象的jclass :它不是靜態方法:
main_activity->env->CallVoidMethod(main_activity.clazz, _method)
注意native_activity.h中的注釋:
/** * The NativeActivity object handle. * * IMPORTANT NOTE: This member is mis-named. It should really be named * 'activity' instead of 'clazz', since it's a reference to the * NativeActivity instance created by the system for you. * * We unfortunately cannot change this without breaking NDK * source-compatibility. */ jobject clazz;
另外,您只能從主(UI)線程中顯示() AlertDialog。 您的C ++代碼建議您從后台線程執行操作。
如果此代碼在主線程上執行,則
main_activity->vm->DetachCurrentThread()
應該刪除。 AttachThread()也可以刪除,但是在已經連接的線程上調用時是NOP。
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