當調用本地方法時返回java.lang.UnsatisfiedLinkError

Question

我想爲第三方DLL製作Java包裝。我創建了自己的DLL，充當JNI和第三方DLL之間的中間人。在Java中我加載這個DLL很好，但返回錯誤java.lang.UnsatisfiedLinkError: sixense.Sixense.init()Z。什麼可能導致這個錯誤，我該如何正確調試它？

Main.java：

package sixense_test; 

import sixense.ControllerData; 
import sixense.Sixense; 

public class Main { 

    public static ControllerData[] controllers = new ControllerData[4]; 
    public static boolean quit; 

    public static void main(String[] args) { 
     if(Sixense.init()) { 
      Sixense.setActiveBase(0); 
      Sixense.getAllNewestData(controllers); 
      System.out.println("X: " + controllers[0].pos[0] + "Y: " + controllers[0].pos[1] + "Z: " + controllers[0].pos[2]); 
     } 
    } 
} 

Sixense.java：

package sixense; 

public class Sixense { 
    public static native boolean init(); 
    public static native boolean exit(); 
    public static native int getMaxBases(); 
    public static native boolean setActiveBase(int base_num); 
    public static native boolean isBaseConnected(int base_num); 
    public static native int getMaxControllers(); 
    public static native int getNumActiveControllers(); 
    public static native boolean isControllerEnabled(int controller_id); 
    public static native boolean getAllNewestData(ControllerData[] all_data); 
    public static native boolean getAllData(int index_back, ControllerData[] all_data); 
    public static native boolean getNewestData(int controller_id, ControllerData data); 
    public static native boolean getData(int controller_id, int index_back, ControllerData all_data); 
    public static native int getHistorySize(); 
    public static native boolean setFilterEnabled(boolean on_or_off); 
    public static native boolean getFilterEnabled(); 
    public static native boolean setFilterParams(float near_range, float near_val, float far_range, float far_val); 
    public static native boolean getFilterParams(float[] params); 
    public static native boolean triggerVibration(int controller_id, int duration, int pattern_id); 
    public static native boolean autoEnableHemisphereTracking(int controller_id); 
    public static native boolean setHighPriorityBinding(boolean on_or_off); 
    public static native boolean getHighPriorityBinding(); 
    public static native boolean setBaseColor(int red, int green, int blue); 
    public static native boolean getColorBase(int[] colors); 
    static { 
     System.loadLibrary("Sixense_Java"); 
    } 
} 

從sixense_Sixense.cpp的摘錄：

#include <jni.h> 
#include <sixense.h> 
#include "sixense_Sixense.h" 

JNIEXPORT jboolean JNICALL Java_sixense_Sixense_init(JNIEnv *env, jclass obj) { 
    int i; 
    i = sixenseInit(); 
    return (i == -1) ? JNI_FALSE : JNI_TRUE; 
} 

從sixense_Sixense.h的摘錄：

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

#ifndef _Included_sixense_Sixense 
#define _Included_sixense_Sixense 
#ifdef __cplusplus 
extern "C" { 
#endif 
/* 
* Class:  sixense_Sixense 
* Method: init 
* Signature:()Z 
*/ 
JNIEXPORT jboolean JNICALL Java_sixense_Sixense_init 
    (JNIEnv *, jclass); 

從DUMPBIN

輸出：

File Type: DLL 

    Section contains the following exports for Sixense_Java.dll 

    00000000 characteristics 
    4FFBC481 time date stamp Tue Jul 10 01:58:25 2012 
     0.00 version 
      1 ordinal base 
      23 number of functions 
      23 number of names 

    ordinal hint RVA  name 

      1 0 00001D10 Java_sixense_Sixense_autoEnableHemisphereTracking@12 
      2 1 000011A0 Java_sixense_Sixense_exit@8 
      3 2 00001A40 Java_sixense_Sixense_getAllData@16 
      4 3 000019A0 Java_sixense_Sixense_getAllNewestData@12 
      5 4 00001DC0 Java_sixense_Sixense_getColorBase@12 
      6 5 00001B30 Java_sixense_Sixense_getData@20 
      7 6 00001BD0 Java_sixense_Sixense_getFilterEnabled@8 
      8 7 00001C40 Java_sixense_Sixense_getFilterParams@12 
      9 8 00001D60 Java_sixense_Sixense_getHighPriorityBinding@8 
     10 9 00001B90 Java_sixense_Sixense_getHistorySize@8 
     11 A 000011C0 Java_sixense_Sixense_getMaxBases@8 
     12 B 00001210 Java_sixense_Sixense_getMaxControllers@8 
     13 C 00001AE0 Java_sixense_Sixense_getNewestData@16 
     14 D 00001220 Java_sixense_Sixense_getNumActiveControllers@8 
     15 E 00001180 Java_sixense_Sixense_init@8 
     16 F 000011F0 Java_sixense_Sixense_isBaseConnected@12 
     17 10 000Java_sixense_Sixense_isControllerEnabled@12 
     18 11 000011D0 Java_sixense_Sixense_setActiveBase@12 
     19 12 00001D90 Java_sixense_Sixense_setBaseColor@20 
     20 13 00001BA0 Java_sixense_Sixense_setFilterEnabled@12 
     21 14 00001C00 Java_sixense_Sixense_setFilterParams@24 
     22 15 00001D30 Java_sixense_Sixense_setHighPriorityBinding@12 
     23 16 00001CE0 Java_sixense_Sixense_triggerVibration@20 

    Summary 

     1000 .bss 
     1000 .data 
     1000 .edata 
     1000 .idata 
     1000 .rdata 
     1000 .reloc 
     2000 .text 

Answer 1

當調用Java中的原生功能，運行時嘗試使用：

• 一個STDCALL風格的裝飾功能：_functionName@n，其中n是在參數列表中的字節數，
• 和cdecl-style undecorated功能：functionName。

當使用MinGW編譯，你會得到這兩種的混合：MinGW的將追加@n，但不會在前面加上下劃線：functionName@n。

解決此問題的方法是告訴ld不要使用--kill-at開關（或如果通過GCC調用-Wl,--kill-at）添加後綴。

Answer 2

java.lang.UnsatisfiedLinkError: no Sixense_Java in java.library.path 

看起來像Java不能找到庫，你把它放到正確的地方？

您可能需要更改java.library.path，看看this。

如果你想打印它的內容使用：

System.out.println(System.getProperties().getProperty("java.library.path")); 

這可能會打印很多，你可能想split(";")和打印自己的每個條目。

Answer 3

我找到了答案！看起來，在Windows中使用JNI時，它尋找一個從_Java_開始的函數，而在其他任何平臺上它都會尋找Java_。爲什麼這是這種情況，而不是寫在我不知道的文檔中，但它使一切完美無缺！