Question

我正在开发一个调用本机dll库的Java应用程序。我调用的c ++方法的代码：

JNIEXPORT jobjectArray JNICALL Java_Surf_TopSurfWrapp_computeSurfExtractDescriptor__LSurf_TopSurfVisualword_2Ljava_lang_String_2(JNIEnv *env, jclass c, jobject vw, jstring imagePath)
{
c = env->GetObjectClass(vw);
printf("start\n");
jobjectArray ret = (jobjectArray) env->NewObjectArray(100, c, vw);

for (int i = 0; i < 100; i++)
{
    jmethodID visualWordConstructor = env->GetMethodID(c, "<init>", "(IFFIFFFF)V");
    jobject element = env->NewObject(c, visualWordConstructor, 1, 1.0, 1.0, 1, 1.0, 1.0, 1.0, 1.0);
    env->SetObjectArrayElement(ret, i, element);
}
    printf("end\n");
return ret;
}

我省略了一些计算，但问题似乎是当JNI返回jobjectArray时。我的Java代码：

public class Wrapp {
    native public static TopSurfVisualword[] computeSurfExtractDescriptor(TopSurfVisualword initVW, String imagePath);
    static {
        System.loadLibrary("TopSurfWrapp");
    }

    public static void main(String[] args) {
    TopSurfVisualword[] d = TopSurfWrapp.computeSurfExtractDescriptor(new TopSurfVisualword(), "d:\\oil.jpg");
    }
}

我收到以下JVM错误：

debug:
#
# A fatal error has been detected by the Java Runtime Environment:
#
#  EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x0000000076d73332, pid=3384, tid=1572
#
# JRE version: 7.0-b147
# Java VM: Java HotSpot(TM) 64-Bit Server VM (21.0-b17 mixed mode windows-amd64 compressed oops)
# Problematic frame:
# C  [ntdll.dll+0x53332]
#
# Failed to write core dump. Minidumps are not enabled by default on client versions of Windows
#
# An error report file with more information is saved as:
# D:\Programming\Visual Studio projects\GPC\TopSurfWrapp\x64\Release\hs_err_pid3384.log
#
# If you would like to submit a bug report, please visit:
#   http://bugreport.sun.com/bugreport/crash.jsp
# The crash happened outside the Java Virtual Machine in native code.
# See problematic frame for where to report the bug.
#
start
end
Java Result: 1

因为我正在开始＆＃34;开始＆＃34;和＆＃34;结束＆＃34;消息我假设问题在于返回数组。有问题的框架似乎是在ntdll.dll（这不是我的动态库）。请帮忙。

Answer 1

我在我的系统上测试了你的样本，运行正常。

一些调试提示...

1）在本机代码中使用printf进行debuging时，请使用fflush跟踪每个printf。

printf("debug message\n");
fflush(stdout);

2）检查JNI函数的空返回值。

jmethodID visualWordConstructor = env->GetMethodID(c, "<init>", "(IFFIFFFF)V"); 
if(visualWordConstructor==0) {
    // print/fflush an error message or throw an exception or both
    // stop processing and return to java now
}

3）在JNI期间打印到stdout和异常/错误可能很棘手。请尝试以下方法来观察行为。

jclass rx = env->FindClass("java/lang/RuntimeException");
printf("start\n");
fflush(stdout);

env->ThrowNew(rx, "thrown from native code");

printf("end\n");
fflush(stdout);

您将首先看到“结束”，然后看到例外情况这是预期的，因为JNI期间有例外排队直到java方获得控制权。

JNI本机DLL没有返回jobjectArray崩溃VM

1 个答案: