超能力 NDK 安卓:返回 int 在"extern"块中成功,在调用函数中失败
Superpowered NDK Android: returning int succeeds in "extern" block, fails in called function
我正试图弄清楚如何从C++函数向Java返回int。
在Java方面,我在一个按钮中有以下内容。我把它放在一个按钮中,以确保在尝试执行returnInt()之前应用程序已完全加载。
int testInt;
testInt = returnInt();
Log.i(TAG, "testInt");
Log.i(TAG, String.valueOf(testInt));
和
private native int returnInt();
在C++方面,在extern
块中返回int成功:
extern "C" JNIEXPORT jint Java_com_superpowered_crossexample_MainActivity_returnInt(JNIEnv * __unused javaEnvironment, jobject __unused obj) {
return 50;
}
但是使用SIGILL
:尝试以下操作失败
jint SuperpoweredExample::returnInt() {
__android_log_print(ANDROID_LOG_VERBOSE, "CrossExample ", "returnInt"); // this runs
return 50; // This fails with SIGILL
}
extern "C" JNIEXPORT jint Java_com_superpowered_crossexample_MainActivity_returnInt(JNIEnv * __unused javaEnvironment, jobject __unused obj) {
// fails with SIGILL
example->returnInt();
}
知道为什么上面会产生SIGILL
吗?
我正在用Superpowered提供的CrossExample项目的克隆进行测试。(我只是用CrossExample作为一种简单的方式,让一个功能强大的项目发挥作用。)
我的项目在这里:
https://github.com/mhurwicz/myCrossExample
这个返回int的尝试在我的项目的myCrossExample1
分支中。
如果出于任何原因你想要它,最初的Superpowered项目就在这里:
https://github.com/superpoweredSDK/Low-Latency-Android-Audio-iOS-Audio-Engine
以下是调试输出:
Signal = SIGILL (signal SIGILL: illegal instruction operand)
javaEnvironment = {JNIEnv * | 0xb40d9a80} 0xb40d9a80
[0] = {JNIEnv}
functions = {const JNINativeInterface * | 0xb4032a40} 0xb4032a40
[0] = {const JNINativeInterface}
reserved0 = {void * | 0x0} nil
reserved1 = {void * | 0x0} nil
reserved2 = {void * | 0x0} nil
reserved3 = {void * | 0x0} nil
GetVersion = {jint (*)(JNIEnv *) | 0xb3a505f5} (libart.so`art::CheckJNI::GetVersion(_JNIEnv*))
DefineClass = {jclass (*)(JNIEnv *, const char *, jobject, const jbyte *, jsize) | 0xb3a51ad0} (libart.so`art::CheckJNI::DefineClass(_JNIEnv*, char const*, _jobject*, signed char const*, int))
FindClass = {jclass (*)(JNIEnv *, const char *) | 0xb3a51f8c} (libart.so`art::CheckJNI::FindClass(_JNIEnv*, char const*))
FromReflectedMethod = {jmethodID (*)(JNIEnv *, jobject) | 0xb3a52c2f} (libart.so`art::CheckJNI::FromReflectedMethod(_JNIEnv*, _jobject*))
FromReflectedField = {jfieldID (*)(JNIEnv *, jobject) | 0xb3a531b4} (libart.so`art::CheckJNI::FromReflectedField(_JNIEnv*, _jobject*))
ToReflectedMethod = {jobject (*)(JNIEnv *, jclass, jmethodID, jboolean) | 0xb3a536f0} (libart.so`art::CheckJNI::ToReflectedMethod(_JNIEnv*, _jclass*, _jmethodID*, unsigned char))
GetSuperclass = {jclass (*)(JNIEnv *, jclass) | 0xb3a523d8} (libart.so`art::CheckJNI::GetSuperclass(_JNIEnv*, _jclass*))
IsAssignableFrom = {jboolean (*)(JNIEnv *, jclass, jclass) | 0xb3a527f0} (libart.so`art::CheckJNI::IsAssignableFrom(_JNIEnv*, _jclass*, _jclass*))
ToReflectedField = {jobject (*)(JNIEnv *, jclass, jfieldID, jboolean) | 0xb3a53b50} (libart.so`art::CheckJNI::ToReflectedField(_JNIEnv*, _jclass*, _jfieldID*, unsigned char))
Throw = {jint (*)(JNIEnv *, jthrowable) | 0xb3a53fb0} (libart.so`art::CheckJNI::Throw(_JNIEnv*, _jthrowable*))
ThrowNew = {jint (*)(JNIEnv *, jclass, const char *) | 0xb3a544c0} (libart.so`art::CheckJNI::ThrowNew(_JNIEnv*, _jclass*, char const*))
ExceptionOccurred = {jthrowable (*)(JNIEnv *) | 0xb3a549da} (libart.so`art::CheckJNI::ExceptionOccurred(_JNIEnv*))
ExceptionDescribe = {void (*)(JNIEnv *) | 0xb3a54dd0} (libart.so`art::CheckJNI::ExceptionDescribe(_JNIEnv*))
ExceptionClear = {void (*)(JNIEnv *) | 0xb3a55200} (libart.so`art::CheckJNI::ExceptionClear(_JNIEnv*))
FatalError = {void (*)(JNIEnv *, const char *) | 0xb3a55a30} (libart.so`art::CheckJNI::FatalError(_JNIEnv*, char const*))
PushLocalFrame = {jint (*)(JNIEnv *, jint) | 0xb3a55e3e} (libart.so`art::CheckJNI::PushLocalFrame(_JNIEnv*, int))
PopLocalFrame = {jobject (*)(JNIEnv *, jobject) | 0xb3a5625d} (libart.so`art::CheckJNI::PopLocalFrame(_JNIEnv*, _jobject*))
NewGlobalRef = {jobject (*)(JNIEnv *, jobject) | 0xb3a56bd5} (libart.so`art::CheckJNI::NewGlobalRef(_JNIEnv*, _jobject*))
DeleteGlobalRef = {void (*)(JNIEnv *, jobject) | 0xb3a572d9} (libart.so`art::CheckJNI::DeleteGlobalRef(_JNIEnv*, _jobject*))
DeleteLocalRef = {void (*)(JNIEnv *, jobject) | 0xb3a5729f} (libart.so`art::CheckJNI::DeleteLocalRef(_JNIEnv*, _jobject*))
IsSameObject = {jboolean (*)(JNIEnv *, jobject, jobject) | 0xb3a57740} (libart.so`art::CheckJNI::IsSameObject(_JNIEnv*, _jobject*, _jobject*))
NewLocalRef = {jobject (*)(JNIEnv *, jobject) | 0xb3a56b9b} (libart.so`art::CheckJNI::NewLocalRef(_JNIEnv*, _jobject*))
EnsureLocalCapacity = {jint (*)(JNIEnv *, jint) | 0xb3a57313} (libart.so`art::CheckJNI::EnsureLocalCapacity(_JNIEnv*, int))
AllocObject = {jobject (*)(JNIEnv *, jclass) | 0xb3a57b90} (libart.so`art::CheckJNI::AllocObject(_JNIEnv*, _jclass*))
NewObject = {jobject (*)(JNIEnv *, jclass, jmethodID, ...) | 0xb3a5867c} (libart.so`art::CheckJNI::NewObject(_JNIEnv*, _jclass*, _jmethodID*, ...))
NewObjectV = {jobject (*)(JNIEnv *, jclass, jmethodID, va_list) | 0xb3a580a5} (libart.so`art::CheckJNI::NewObjectV(_JNIEnv*, _jclass*, _jmethodID*, char*))
NewObjectA = {jobject (*)(JNIEnv *, jclass, jmethodID, jvalue *) | 0xb3a586a7} (libart.so`art::CheckJNI::NewObjectA(_JNIEnv*, _jclass*, _jmethodID*, jvalue*))
GetObjectClass = {jclass (*)(JNIEnv *, jobject) | 0xb3a58c7e} (libart.so`art::CheckJNI::GetObjectClass(_JNIEnv*, _jobject*))
IsInstanceOf = {jboolean (*)(JNIEnv *, jobject, jclass) | 0xb3a59090} (libart.so`art::CheckJNI::IsInstanceOf(_JNIEnv*, _jobject*, _jclass*))
GetMethodID = {jmethodID (*)(JNIEnv *, jclass, const char *, const char *) | 0xb3a599b0} (libart.so`art::CheckJNI::GetMethodID(_JNIEnv*, _jclass*, char const*, char const*))
CallObjectMethod = {jobject (*)(JNIEnv *, jobject, jmethodID, ...) | 0xb3a6a042} (libart.so`art::CheckJNI::CallObjectMethod(_JNIEnv*, _jobject*, _jmethodID*, ...))
CallObjectMethodV = {jobject (*)(JNIEnv *, jobject, jmethodID, va_list) | 0xb3a69fd9} (libart.so`art::CheckJNI::CallObjectMethodV(_JNIEnv*, _jobject*, _jmethodID*, char*))
CallObjectMethodA = {jobject (*)(JNIEnv *, jobject, jmethodID, jvalue *) | 0xb3a67197} (libart.so`art::CheckJNI::CallObjectMethodA(_JNIEnv*, _jobject*, _jmethodID*, jvalue*))
CallBooleanMethod = {jboolean (*)(JNIEnv *, jobject, jmethodID, ...) | 0xb3a69f6f} (libart.so`art::CheckJNI::CallBooleanMethod(_JNIEnv*, _jobject*, _jmethodID*, ...))
CallBooleanMethodV = {jboolean (*)(JNIEnv *, jobject, jmethodID, va_list) | 0xb3a69f05} (libart.so`art::CheckJNI::CallBooleanMethodV(_JNIEnv*, _jobject*, _jmethodID*, char*))
CallBooleanMethodA = {jboolean (*)(JNIEnv *, jobject, jmethodID, jvalue *) | 0xb3a6712d} (libart.so`art::CheckJNI::CallBooleanMethodA(_JNIEnv*, _jobject*, _jmethodID*, jvalue*))
CallByteMethod = {jbyte (*)(JNIEnv *, jobject, jmethodID, ...) | 0xb3a69e9b} (libart.so`art::CheckJNI::CallByteMethod(_JNIEnv*, _jobject*, _jmethodID*, ...))
CallByteMethodV = {jbyte (*)(JNIEnv *, jobject, jmethodID, va_list) | 0xb3a69e31} (libart.so`art::CheckJNI::CallByteMethodV(_JNIEnv*, _jobject*, _jmethodID*, char*))
CallByteMethodA = {jbyte (*)(JNIEnv *, jobject, jmethodID, jvalue *) | 0xb3a670c3} (libart.so`art::CheckJNI::CallByteMethodA(_JNIEnv*, _jobject*, _jmethodID*, jvalue*))
CallCharMethod = {jchar (*)(JNIEnv *, jobject, jmethodID, ...) | 0xb3a69dc7} (libart.so`art::CheckJNI::CallCharMethod(_JNIEnv*, _jobject*, _jmethodID*, ...))
CallCharMethodV = {jchar (*)(JNIEnv *, jobject, jmethodID, va_list) | 0xb3a69d5d} (libart.so`art::CheckJNI::CallCharMethodV(_JNIEnv*, _jobject*, _jmethodID*, char*))
CallCharMethodA = {jchar (*)(JNIEnv *, jobject, jmethodID, jvalue *) | 0xb3a67059} (libart.so`art::CheckJNI::CallCharMethodA(_JNIEnv*, _jobject*, _jmethodID*, jvalue*))
CallShortMethod = {jshort (*)(JNIEnv *, jobject, jmethodID, ...) | 0xb3a69cf3} (libart.so`art::CheckJNI::CallShortMethod(_JNIEnv*, _jobject*, _jmethodID*, ...))
CallShortMethodV = {jshort (*)(JNIEnv *, jobject, jmethodID, va_list) | 0xb3a69c89} (libart.so`art::CheckJNI::CallShortMethodV(_JNIEnv*, _jobject*, _jmethodID*, char*))
CallShortMethodA = {jshort (*)(JNIEnv *, jobject, jmethodID, jvalue *) | 0xb3a66fef} (libart.so`art::CheckJNI::CallShortMethodA(_JNIEnv*, _jobject*, _jmethodID*, jvalue*))
CallIntMethod = {jint (*)(JNIEnv *, jobject, jmethodID, ...) | 0xb3a69c20} (libart.so`art::CheckJNI::CallIntMethod(_JNIEnv*, _jobject*, _jmethodID*, ...))
obj = {jobject | 0xbfcc426c} 0xbfcc426c
在SuperpoweredExample()
之前调用returnInt()
。因此,您正在取消引用一个NULL指针example
。
此外,您没有从声明为返回jint
的函数中返回任何内容
您需要:
extern "C" JNIEXPORT jint Java_com_superpowered_crossexample_MainActivity_returnInt(JNIEnv * __unused javaEnvironment, jobject __unused obj) {
return example->returnInt();
}
相关文章:
- 什么时候调用组成单元对象的析构函数
- 对RValue对象调用的LValue ref限定成员函数
- 为什么使用 "this" 指针调用派生成员函数?
- 无法使用 JNI 从C++模块成功调用 Java 函数
- 为什么插槽函数即使成功调用也无法插入文本
- 有没有办法在编译时检测是否可以使用一组给定的参数类型成功调用通用 lambda?
- 超能力 NDK 安卓:返回 int 在"extern"块中成功,在调用函数中失败
- 如果给定的寄存器classex()调用成功一次,我可以认为它总是会的
- 为什么WNetAddConnection2在成功调用WNetCancelConnection2后仍返回1219
- 尽管连接成功,但未调用插槽
- 为什么非虚拟函数调用即使在dynamic_cast失败后仍然成功
- Winsock TCP侦听器在成功执行closesocket()调用后保持LISTENING状态
- 在来自C++应用程序的成功调用之间保留dll中的状态
- SetWindowsHookEx成功,但回调函数从未被调用
- c++ ThreadProc没有被调用,尽管CreateThread成功
- 为什么在c++中调用库(构建库是成功的)时会出现链接错误?
- CreateService() 调用成功,即使依赖项不存在
- RegCloseKey()函数应该只在RegOpenKey()调用成功后使用,还是无条件使用?
- 无法成功返回我通过在字符串上调用 c_str() 创建的 const 字符*。(C++)
- c++调用函数不能成功调用函数