C++不能在java中释放对象
我正试图使用JNI将Mat
对象从C++传递到Java。我查看了OpenCV Java dll的源代码,我使用的代码与OpenCV使用的完全相同。当我想从Java中释放由OpenCV Java API创建的Mat
对象时,它可以正常工作,但当我想释放使用相同代码创建的Mat
对象时,我的应用程序崩溃
我正在发布我使用的代码。如果有人有想法,我将不胜感激。提前谢谢
[编辑]
我还想补充一点,如果你看代码块3和4,爪哇和C++边的函数定义有相同的函数名, ReaDimaGe0[/EDIT]
[EDIT2]
在Windows 7、VC11上运行时,使用OpenCV 2.4.5和2.4.8进行了尝试
[/EDIT2]
1。这是在OpenCV源中传递^ ^ 2。这是OpenCV源代码中的Java代码: 3。这是我的代码: 4。这是我的Java代码: 5。我就是这样运行代码的: 6。这是写在例外中的内容: 7。以下是坠机报告中的内容:JNIEXPORT jlong JNICALL Java_org_opencv_highgui_Highgui_imread_11 (JNIEnv*, jclass, jstring);
JNIEXPORT jlong JNICALL Java_org_opencv_highgui_Highgui_imread_11
(JNIEnv* env, jclass , jstring filename)
{
static const char method_name[] = "highgui::imread_11()";
try {
LOGD("%s", method_name);
const char* utf_filename = env->GetStringUTFChars(filename, 0); std::string n_filename( utf_filename ? utf_filename : "" ); env->ReleaseStringUTFChars(filename, utf_filename);
Mat _retval_ = cv::imread( n_filename );
return (jlong) new Mat(_retval_);
} catch(const std::exception &e) {
throwJavaException(env, &e, method_name);
} catch (...) {
throwJavaException(env, 0, method_name);
}
return 0;
}
public static Mat imread(String filename)
{
Mat retVal = new Mat(imread_1(filename));
return retVal;
}
private static native long imread_1(String filename);
JNIEXPORT jlong JNICALL Java_tr_com_guney_opencvcpp2java_OpenCVCpp2Java_readImage0(JNIEnv *env, jclass, jstring imagePath)
JNIEXPORT jlong JNICALL Java_tr_com_guney_opencvcpp2java_OpenCVCpp2Java_readImage0(JNIEnv *env, jclass, jstring imagePath)
{
static const char method_name[] = "OpenCVCpp2Java::readImage0()";
try {
LOGD("%s", method_name);
const char* utf_filename = env->GetStringUTFChars(imagePath, 0); std::string n_filename( utf_filename ? utf_filename : "" ); env->ReleaseStringUTFChars(imagePath, utf_filename);
cv::Mat _retval_ = cv::imread( n_filename );
return (jlong) new cv::Mat(_retval_);
} catch(const std::exception &e) {
throwJavaException(env, &e, method_name);
} catch (...) {
throwJavaException(env, 0, method_name);
}
return 0;
}
public static Mat readImage(String imagePath)
{
Mat retVal = new Mat(readImage0(imagePath));
return retVal;
}
private static native long readImage0(String imagePath);
Mat image = Highgui.imread("e:/image.png"); //this works fine
Highgui.imwrite("e:/imageJava.png", image); // this is to check if image is read correctly and works fine
image.release(); // this works fine
//system.gc(); // this also works fine
Mat image2 = OpenCVCpp2Java.readImage("e:/image.png"); //this works fine
Highgui.imwrite("e:/imageJava2.png", image2); // this is to check if image is read correctly and works fine
image2.release(); // this throws exception!
//system.gc(); // this causes application to crash!
Exception in thread "main" java.lang.Exception: Unknown exception in JNI code {Mat::n_1release()}
at org.opencv.core.Mat.n_release(Native Method)
at org.opencv.core.Mat.release(Mat.java:1875)
Stack: [0x28880000,0x288d0000], sp=0x288cf620, free space=317k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
C [ntdll.dll+0x2e3be] RtlInitUnicodeString+0x196
C [ntdll.dll+0x2e023] RtlFreeHeap+0x7e
C [kernel32.dll+0x114ad] HeapFree+0x14
C [opencv_java245.dll+0x48e877] Java_org_opencv_contrib_Contrib_chamerMatching_11+0x429a47
C [opencv_java245.dll+0x904f3] Java_org_opencv_contrib_Contrib_chamerMatching_11+0x2b6c3
C [opencv_java245.dll+0x6516a] Java_org_opencv_contrib_Contrib_chamerMatching_11+0x33a
j org.opencv.core.Mat.n_delete(J)V+0
j org.opencv.core.Mat.finalize()V+4
v ~StubRoutines::call_stub
V [jvm.dll+0xfb88b]
V [jvm.dll+0x18d551]
V [jvm.dll+0xfb90d]
V [jvm.dll+0x96301]
V [jvm.dll+0x990c9]
C [java.dll+0x2100] Java_java_lang_ref_Finalizer_invokeFinalizeMethod+0x39
j java.lang.ref.Finalizer.runFinalizer()V+45
j java.lang.ref.Finalizer.access$100(Ljava/lang/ref/Finalizer;)V+1
j java.lang.ref.Finalizer$FinalizerThread.run()V+24
v ~StubRoutines::call_stub
V [jvm.dll+0xfb88b]
V [jvm.dll+0x18d551]
V [jvm.dll+0xfba31]
V [jvm.dll+0xfba8b]
V [jvm.dll+0xb5e89]
V [jvm.dll+0x119b74]
V [jvm.dll+0x14217c]
C [msvcr71.dll+0x9565] endthreadex+0xa0
C [kernel32.dll+0x1336a] BaseThreadInitThunk+0x12
C [ntdll.dll+0x39f72] RtlInitializeExceptionChain+0x63
C [ntdll.dll+0x39f45] RtlInitializeExceptionChain+0x36
Java frames: (J=compiled Java code, j=interpreted, Vv=VM code)
j org.opencv.core.Mat.n_delete(J)V+0
j org.opencv.core.Mat.finalize()V+4
v ~StubRoutines::call_stub
j java.lang.ref.Finalizer.invokeFinalizeMethod(Ljava/lang/Object;)V+0
j java.lang.ref.Finalizer.runFinalizer()V+45
j java.lang.ref.Finalizer.access$100(Ljava/lang/ref/Finalizer;)V+1
j java.lang.ref.Finalizer$FinalizerThread.run()V+24
v ~StubRoutines::call_stub
# 1 楼答案
我已经知道问题出在哪里了。我觉得这有点复杂,至少对我来说是这样
问题是我使用的是opencv_java248。与OpenCV一起分发并已编译的dll。opencv_java248。dll是静态构建的,这意味着编译后它不需要任何OpenCV dll(OpenCV_core248.dll等)。我已经创建了自己的dll opencvcpp2java。dll,它也是静态构建的,因此在运行时不需要任何dll
在我撞车后,我开始思考是什么导致了这个问题。然后我意识到,内存分配和释放是在完全不同的dll上完成的。我在用opencvcpp2java分配内存。dll,并期待opencv_java248。dll来发布它。当它试图释放它时,程序崩溃了。另一方面,当我使用opencv_java248进行分配和解除分配时。没有问题。所以,凭直觉,我认为分配和解除分配应该在同一个dll上完成
基于这种直觉,我编译了opencv_java248。dll我自己(顺便说一句,你需要编译所有的OpenCV dll,当你使用CMake时这是小菜一碟),并使其依赖于其他OpenCV dll和重新编译的opencvcpp2java。dll,并使其依赖于OpenCV dll。所以当我想使用opencvcpp2java分配内存时。dll它使用OpenCV dll的分配内存(更具体地说是OpenCV_core248.dll),当我想使用OpenCV_java248释放内存时。dll它使用创建的相同dll解除分配内存
我不是100%确定这是正确的解决方案,但它对我有效