Question

我有一个调用C dll的c＃程序，后者又调用java dll（使用jet excelsior构建第三方程序）。我将一个xml字符串从c＃传递到java中，然后java将字符串返回到c＃进行处理。

这适用于第一次迭代，但是在第二次迭代时我得到以下异常......

尝试读取或写入受保护的内存。这通常是一个表明其他内存已损坏。

以下是我将其列为相关代码的内容，但如果您需要其他任何内容，请告知我们。

C＃调用C dll

public static class DllCall
{
    [DllImport("Stubs", CallingConvention = CallingConvention.Cdecl)]
    public static extern int initDll([MarshalAs(UnmanagedType.LPStr)] string userDllName);

    [DllImport("Stubs", CallingConvention = CallingConvention.Cdecl)]
    public static extern void finalizeDll();

    [DllImport("Stubs", CallingConvention = CallingConvention.Cdecl)]
    public static extern UInt32 newClassInstance(String rootPath, String cfgPath, String logPath );

    [DllImport("Stubs", CallingConvention = CallingConvention.Cdecl)]
    public static extern String request(UInt32 hClassInst, [MarshalAs(UnmanagedType.LPStr)] String input);

    [DllImport("Stubs", CallingConvention = CallingConvention.Cdecl)]
    public static extern void close();


}

C dll中抛出错误的方法

const char* request(jobject obj, char* input )
{
    jstring inputString;
    jstring outputString;
    const char *nativeString;


    jmethodID mID = (*env)->GetMethodID (env, jClass, "request", "(Ljava/lang/String;)Ljava/lang/String;");
    if (!mID){
        printf("\nError: dllClass.request() not found\n");
        return 0;
    }

    inputString = (*env)->NewStringUTF(env, input);


    outputString = (*env)->CallObjectMethod(env, obj, mID, inputString);    

    nativeString = (*env)->GetStringUTFChars(env, outputString, 0); 


    return nativeString;
}

这里要求的是实际导致异常的C＃代码。

        public string request(string xmlInput)
{
    LogManager.logMessage("Sending request to Java. Request is - " + xmlInput);
    string rs ="";
    Console.Write("Making request");
    //this works fine
    rs = DllCall.request(hClass, xmlInput); 
    Console.Write("---> request() rs = {0}\n", rs);
    // this throws the error
    rs = DllCall.request(hClass, "<?xml version='1.0' encoding='utf-8'?><moo><request name=\"Panel.Open.GetSelectionTemplate\"/></moo>"); 
    return rs;
}

在回应丹尼尔时，这里宣布了env

#include <jni.h>
#include <windows.h>

JNIEnv  *env;
JavaVM  *jvm;
HANDLE  hUserDll;
jclass  jClass;
char*  dllname;

这是如何初始化的。

int initDll(char* userDllName) 
{
  jClass = NULL;
  hUserDll = loadDll(userDllName); 
  dllname = userDllName;
  initJavaRT(hUserDll, &jvm, &env); 
  jClass = lookForClass(env, "XActMain/XActGeminiX3/XActGeminiX3IFX");
  return jClass ? 1 : 0;
}

/*
 * Initialize JET run-time.
 */
void initJavaRT(HANDLE myDllHandle, JavaVM** pjvm, JNIEnv** penv)
{
    int            result;
    JavaVMInitArgs args;

    JNI_GetDefaultJavaVMInitArgs_func = 
             (jint (JNICALL *) (void *args))
             GetProcAddress (myDllHandle, "JNI_GetDefaultJavaVMInitArgs");

    JNI_CreateJavaVM_func =
             (jint (JNICALL *) (JavaVM **pvm, void **penv, void *args))
             GetProcAddress (myDllHandle, "JNI_CreateJavaVM");

    if(!JNI_GetDefaultJavaVMInitArgs_func) {
        printf ("%s doesn't contain public JNI_GetDefaultJavaVMInitArgs\n", dllname);
        exit (1);
    }

    if(!JNI_CreateJavaVM_func) {
        printf ("%s doesn't contain public JNI_CreateJavaVM\n", dllname);
        exit (1);
    }

    memset (&args, 0, sizeof(args));
    args.version = JNI_VERSION_1_2;

    result = JNI_GetDefaultJavaVMInitArgs_func(&args);
    if (result != JNI_OK) {
        printf ("JNI_GetDefaultJavaVMInitArgs() failed with result %d\n", result);
        exit(1);
    }

    /*
     * NOTE: no JVM is actually created
     * this call to JNI_CreateJavaVM is intended for JET RT initialization
     */
    result = JNI_CreateJavaVM_func (pjvm, (void **)penv, &args);
    if (result != JNI_OK) {
        printf ("JNI_CreateJavaVM() failed with result %d\n", result);
        exit(1);
    }

    printf ("JET RT initialized\n");
    fflush (stdout);
}

这是对Joes关于初始化的评论......

public class Test
 {
     public UInt32 hClass;

     public Test()
     {
        initDll();
        newClassInstance(rootConfig, config, logFile);
     }

     ........

     public void newClassInstance(string rootPath, string cfgPath, string logPath)
     {
         hClass = DllCall.newClassInstance(rootPath, cfgPath, logPath);
         Console.Write("---> hClass = {0}\n", hClass);
     }
     public void initDll()
     {
             int rc = DllCall.initDll("dllClass.dll");
             Console.Write("---> initDll() rc = {0}\n", rc);
     }

汉斯指出了以下链接potential answer

但我不知道如何修改我当前的代码以适应此解决方案。

正如我所说的，它会工作一次然后在第二次迭代时崩溃。

Answer 1

我不确定它为什么第一次工作，但你将一个类对象（hClass）传递给request而不是该类的实例。

rs = DllCall.request(hClass, xmlInput); //The error is thrown on this line

看看这是否解决了问题：

public string request(string xmlInput)
{
    LogManager.logMessage("Sending request to Java. Request is - " + xmlInput);
    string rs ="";
    Console.Write("Making request");

    UInt32 hClassInst = DllCall.newClassInstance(rootPath, cfgPath, logPath); // <-- New line, using your own rootPath, cfgPath, logPath variables
    rs = DllCall.request(hClassInst, xmlInput);                               // <-- Modified line, using hClassInst instead of hClass

    Console.Write("---> request() rs = {0}\n", rs);
    return rs;
}

如果这样可以解决问题，那么您应该重构它并将newClassInstance调用拉出到先前的初始化方法。

访问冲突异常

1 个答案: