Question

我正在尝试从自己创建的DLL文件访问第三方DLL，但是在使用JNI调用自己的DLL时遇到JVM内存访问冲突。

我尝试调用的第三方dll是cfint64.dll。对于兼容性问题，我正在创建自己的dll来访问第三方dll。

我不知道第三方cfint64.dll使用了什么编译器，但是它应该用于64位计算机。

在我这边，这就是我创建自己的DLL的方式：g ++ -I“％JAVA_HOME％\ include” -I“％JAVA_HOME％\ include \ win32”-共享-o dll3minterface.dll DLL3MInterface.cpp

我知道第三方dll具有以下功能签名：

/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class dllCommunication */

#ifndef _Included_dllCommunication
#define _Included_dllCommunication
#ifdef __cplusplus
extern "C" {
#endif
/*
 * Class:     dllCommunication
 * Method:    nJavaInitInstance
 * Signature: (Ljava/lang/String;)I
 */
JNIEXPORT jint JNICALL Java_dllCommunication_nJavaInitInstance
  (JNIEnv *, jobject, jstring);



#ifdef __cplusplus
}
#endif
#endif

我创建的头文件如下：

/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class com_artificialmedgui_coderdx_DLL3MInterface */

#ifndef _Included_com_artificialmedgui_coderdx_DLL3MInterface
#define _Included_com_artificialmedgui_coderdx_DLL3MInterface
#ifdef __cplusplus
extern "C" {
#endif
/*
 * Class:     com_artificialmedgui_coderdx_DLL3MInterface
 * Method:    nJavaInitInstance
 * Signature: (Ljava/lang/String;)I
 */
JNIEXPORT jint JNICALL Java_com_artificialmedgui_coderdx_DLL3MInterface_nJavaInitInstance(JNIEnv *, jobject, jstring);

#ifdef __cplusplus
}
#endif
#endif

我的导致内存访问冲突的.cpp文件如下。请注意，导致错误的行是funcCall（inJNIStr）;。如果我注释掉此函数调用，程序将无错误结束。

#include <windows.h>
#include <jni.h>       // JNI header provided by JDK
#include <iostream>    // C++ standard IO header
#include "com_artificialmedgui_coderdx_DLL3MInterface.h"  // Generated
using namespace std;

typedef int (__stdcall* initInstanceFunc)(jstring);

JNIEXPORT jint JNICALL Java_com_artificialmedgui_coderdx_DLL3MInterface_nJavaInitInstance(JNIEnv *env, jobject, jstring inJNIStr) {
    // Step 1: Convert the JNI String (jstring) into C-String (char*)
   const char *inCStr = env->GetStringUTFChars(inJNIStr, NULL);



    HINSTANCE hGetProcIDDLL = LoadLibrary("C:\\workspace\\AMI3MDLLInterface\\resources\\cfint64.dll");

  if (!hGetProcIDDLL) {
    std::cout << "could not load the dynamic library" << std::endl;
    return EXIT_FAILURE;
  }
  else{
      std::cout << "Loaded cfint64.dll library!!!!" << std::endl;
  }

  // resolve function address here
  initInstanceFunc funcCall = (initInstanceFunc)GetProcAddress(hGetProcIDDLL, "Java_dllCommunication_nJavaInitInstance");
     if (*funcCall != NULL) {
      funcCall(inJNIStr);
  }
  else{
      std::cout << "Function is invalid" << std::endl;
  }


       return 1; //Testing
    }

我能够加载第三方cfint64.dll，但是在调用其函数之一时，例如funcCall（inJNIStr）;它抛出错误以下。
也许在调用cfint64.dll函数时没有从我的.cpp文件中传递正确的String数据类型？我不是C ++程序员，所以任何引起问题的想法都值得赞赏。

#
# A fatal error has been detected by the Java Runtime Environment:
#
#  EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x0000000000000000, pid=12276, tid=11080
#
# JRE version: Java(TM) SE Runtime Environment (10.0.1+10) (build 10.0.1+10)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (10.0.1+10, mixed mode, tiered, compressed oops, g1 gc, windows-amd64)
# Problematic frame:
# C  0x0000000000000000
#
# No core dump will be written. Minidumps are not enabled by default on client versions of Windows
#
# If you would like to submit a bug report, please visit:
#   http://bugreport.java.com/bugreport/crash.jsp
# The crash happened outside the Java Virtual Machine in native code.
# See problematic frame for where to report the bug.
#

---------------  S U M M A R Y ------------

Command Line: com.artificialmedgui.coderdx.DLL3MInterface

Host: Intel(R) Core(TM) i7-4720HQ CPU @ 2.60GHz, 8 cores, 15G,  Windows 10 , 64 bit Build 17134 (10.0.17134.648)
Time: Sun Mar 24 14:15:30 2019 Eastern Daylight Time elapsed time: 1 seconds (0d 0h 0m 1s)

---------------  T H R E A D  ---------------

Current thread (0x000001421b910800):  JavaThread "main" [_thread_in_native, id=11080, stack(0x0000003371700000,0x0000003371800000)]

Stack: [0x0000003371700000,0x0000003371800000],  sp=0x00000033717ff258,  free space=1020k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)

Java frames: (J=compiled Java code, j=interpreted, Vv=VM code)
j  com.artificialmedgui.coderdx.DLL3MInterface.nJavaInitInstance(Ljava/lang/String;)I+0
j  com.artificialmedgui.coderdx.DLL3MInterface.main([Ljava/lang/String;)V+17
v  ~StubRoutines::call_stub

siginfo: EXCEPTION_ACCESS_VIOLATION (0xc0000005), data execution prevention violation at address 0x0000000000000000


Register to memory mapping:

RIP=0x0000000000000000 is an unknown value
RAX=0x00000006d0a4b6c0 is an oop
java.lang.String 
{0x00000006d0a4b6c0} - klass: 'java/lang/String'
RBX={method} {0x000001423eb204a8} 'nJavaInitInstance' '(Ljava/lang/String;)I' in 'com/artificialmedgui/coderdx/DLL3MInterface'
RCX=0x00000033717ff380 is pointing into the stack for thread: 0x000001421b910800
RDX=0x0000000000000002 is an unknown value
RSP=0x00000033717ff258 is pointing into the stack for thread: 0x000001421b910800
RBP=0x00000033717ff2d0 is pointing into the stack for thread: 0x000001421b910800
RSI=0x0000000000000002 is an unknown value
RDI=0x00000033717ff380 is pointing into the stack for thread: 0x000001421b910800
R8 =0x0000000000000000 is an unknown value
R9 =0x0000000000000000 is an unknown value
R10=0x0000000000000002 is an unknown value
R11=0x00000033717fef80 is pointing into the stack for thread: 0x000001421b910800
R12=0x0000000000000000 is an unknown value
R13={method} {0x000001423eb204a8} 'nJavaInitInstance' '(Ljava/lang/String;)I' in 'com/artificialmedgui/coderdx/DLL3MInterface'
R14=0x00000033717ff388 is pointing into the stack for thread: 0x000001421b910800
R15=0x000001421b910800 is a thread

Answer 1

我解决了这个问题。也许从一开始我就没有弄清楚这一点，但是我的JNI DLL正在调用另一个第三方JNI DLL。因此，当您从Java代码调用JNI DLL时，只需传递实际参数即可。我猜想在调用实际的DLL函数时，JVM链接器会添加其他参数。无论如何，从我的DLL中，我只必须传递JVM链接程序可能传递的这些附加参数。

调用第二个JNI DLL函数：

Wrong:
typedef int (__stdcall* initInstanceFunc)(jstring);

Works:
typedef int (__stdcall* initInstanceFunc)(JNIEnv*,jobject,jstring);
...
funcCall(env,obj,inJNIStr);

尝试访问DLL函数时从JVM获取EXCEPTION_ACCESS_VIOLATION

1 个答案: