JNI调用非静态函数段错误
我正在为Android的SDL库做一些工作，但我有一点障碍。
此函数在Java中定义：
/** * This method is called by SDL using JNI. * @return an array which may be empty but is never null. */ public static int[] inputGetInputDeviceIds(int sources) { int[] ids = InputDevice.getDeviceIds(); int[] filtered = new int[ids.length]; int used = 0; for (int i = 0; i < ids.length; ++i) { InputDevice device = InputDevice.getDevice(ids[i]); if ((device != null) && ((device.getSources() & sources) != 0)) { filtered[used++] = device.getId(); } } return Arrays.copyOf(filtered, used); } 在JNI / C方面：
/* returns number of found touch devices as return value and ids in parameter ids */ int Android_JNI_GetTouchDeviceIds(int **ids) { JNIEnv *env = Android_JNI_GetEnv(); jint sources = 4098; /* == InputDevice.SOURCE_TOUCHSCREEN */ jmethodID mid = (*env)->GetStaticMethodID(env, mActivityClass, "inputGetInputDeviceIds", "(I)[I"); jintArray array = (jintArray) (*env)->CallStaticObjectMethod(env, mActivityClass, mid, sources); int number = 0; *ids = NULL; if (array) { number = (int) (*env)->GetArrayLength(env, array); if (0 GetIntArrayElements(env, array, NULL); if (elements) { int i; *ids = SDL_malloc(number * sizeof (**ids)); for (i = 0; i ReleaseIntArrayElements(env, array, elements, JNI_ABORT); } } (*env)->DeleteLocalRef(env, array); } return number; }
现在这个工作，但我想编辑它以使调用非静态。 我将Java端代码更改为：
public int[] inputGetInputDeviceIds(int sources) { int[] ids = InputDevice.getDeviceIds(); int[] filtered = new int[ids.length]; int used = 0; for (int i = 0; i < ids.length; ++i) { InputDevice device = InputDevice.getDevice(ids[i]); if ((device != null) && ((device.getSources() & sources) != 0)) { filtered[used++] = device.getId(); } } return Arrays.copyOf(filtered, used); }
从函数名中删除静态。
在JNI方面，我这样做：
/* returns number of found touch devices as return value and ids in parameter ids */ int Android_JNI_GetTouchDeviceIds(int **ids) { JNIEnv *env = Android_JNI_GetEnv(); jint sources = 4098; /* == InputDevice.SOURCE_TOUCHSCREEN */ //jmethodID mid = (*env)->GetStaticMethodID(env, mActivityClass, "inputGetInputDeviceIds", "(I)[I"); //------------ jclass clazz = (*env)->FindClass(env, "org/libsdl/app/SDLActivity"); if (clazz == 0) { __android_log_print(ANDROID_LOG_INFO, "SDL", "find class failed SDL_android.c line 1409"); return; } jmethodID javamethod = (*env)->GetMethodID(env, clazz, "inputGetInputDeviceIds", "(I)[I"); if (javamethod == 0) { __android_log_print(ANDROID_LOG_INFO, "SDL", "find non static method failed SDL_android.c line 1414"); return; } __android_log_print(ANDROID_LOG_INFO, "SDL", "SUCCESS GETTING JNI METHOD FROM ENV SDL_android.c line 1416"); CallObjectMethod(env, clazz, javamethod, sources); CallStaticObjectMethod(env, mActivityClass, mid, sources); int number = 0; *ids = NULL; if (array) { number = (int) (*env)->GetArrayLength(env, array); if (0 GetIntArrayElements(env, array, NULL); if (elements) { int i; *ids = SDL_malloc(number * sizeof (**ids)); for (i = 0; i ReleaseIntArrayElements(env, array, elements, JNI_ABORT); } } (*env)->DeleteLocalRef(env, array); } __android_log_print(ANDROID_LOG_INFO, "SDL", "reached the end of inputGetInputDeviceIds func"); return number; }
有这个错误：
09-19 22:40:53.514: A/libc(29636): Fatal signal 11 (SIGSEGV) at 0x00000001 (code=1), thread 29650 (Thread-22463)
然后我重新编译c libs，清理项目并重新安装应用程序。 代码段错误在那一行，而静态版本没问题。 从查看代码，此函数中没有其他静态引用。
什么可能导致段错误？ 我做了一些测试并改变了其他静态函数，抓住了获取类的env，查找函数并调用它实际上是有效的。
知道为什么会失败吗？
jintArray array = (*env)->CallObjectMethod(env, clazz, javamethod, sources); ^^^^^ This is incorrect
CallObjectMethod的第二个参数不应该是jclass ，而是一个jobject引用要调用该方法的该类的实例。
因此，您需要将SDLActivity实例传递给C函数，以便C函数可以将其传递给CallObjectMethod 。