来自JNI的EXCEPTION_ACCESS_VIOLATION(0xc0000005)JVM吗? [英] EXCEPTION_ACCESS_VIOLATION (0xc0000005) JVM from JNI?

问题描述

我在带有JNI的vc ++中编写了一些本机方法，可以从Java中进行访问.我的三种方法中的两种完全可以正常工作，没有任何问题.但是，当我在运行时调用它时，我的最后一种方法一直导致以下错误消息:

I wrote some native methods in a vc++ with JNI to be accessed from java. Two of my three methods work perfectly fine with no issues. My last method, however, has been causing the following error message when i call it during runtime:

# A fatal error has been detected by the Java Runtime Environment:
#
#  EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x61e06550, pid=3408, tid=4796
#
# JRE version: 7.0-b147
# Java VM: Java HotSpot(TM) Client VM (21.0-b17 mixed mode, sharing windows-x86 )
# Problematic frame:
# V  [jvm.dll+0xa6550]
#
# Failed to write core dump. Minidumps are not enabled by default on client versions of Windows

这是我的本机方法的代码(在vc ++中):

Here is my native method's code (in vc++):

JNIEXPORT jcharArray JNICALL Java_jniusb_Main_receiveData (JNIEnv *env, jclass, jchar dataIndex)
{
    DWORD BytesWritten = 0;
    DWORD BytesRead = 0;
    unsigned char OutputPacketBuffer[65];   
    unsigned char InputPacketBuffer[65];    

    static jcharArray ReturnPacketBuffer;
    jchar temp[65];

    //send 'receive data' command to the firmware (OutputPacketBuffer[1])
    WriteFile(WriteHandle, &OutputPacketBuffer, 65, &BytesWritten, 0);
        //retrieve data from firmware
    ReadFile(ReadHandle, &InputPacketBuffer, 65, &BytesRead, 0);        

        for(int i=0;i<64;i++) 
    {
        temp[i] = jchar(InputPacketBuffer[i+1]);
    }

    (*env).SetCharArrayRegion(ReturnPacketBuffer, 0, 64, temp);
    return ReturnPacketBuffer;
}

我的Java代码看起来像这样(当然是经过删节的):

My Java code looks like this (abridged of course):

public static native char[] receiveData(char dataIndex);

public static void main(String[] args) {
    char vid = 0x4d8;
    char pid = 0x3f;

    //check if read/write handles were retrieved 
    if(connectHid(vid, pid) == true)
    {
        System.out.println("connected!!!");
    }
    else
    {
        System.out.println("not connected...");
    }


    char[] test = new char[64];
    char[] receivetest = new char[64];

    char length = 0x03;
    char dataIndex = 0x81;

    test[0] = 0x80;
    test[1] = 0x80;
    sendData(test, length);
    receivetest = receiveData(dataIndex);

就像我之前说过的那样，其他方法(即connect和senddata)也可以正常工作，但是我从receiveData方法中得到了错误.经过一些调试后，我发现注释掉该行后该错误消失了:

Like I said before, the other methods (i.e. connect and senddata) work fine and but I get the error from the receiveData method. After some debugging I discovered that the error goes away when I comment out the line:

(*env).SetCharArrayRegion(ReturnPacketBuffer, 0, 64, temp);

在我的本机代码中(当然，在这种情况下永远也不会返回数据...).我在这里做错了什么?

in my native code (of course the data never gets returned in this case...). What am I doing wrong here?

推荐答案

您是否错过了类似的东西 ReturnPacketBuffer = (*env)->NewCharArray(env, 64);

Aren't you missing something like ReturnPacketBuffer = (*env)->NewCharArray(env, 64);

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