我有一个包含DLL（LsApi.DLL）的扫描程序API，我必须使用JNI将其方法与JAVA一起使用。我尝试使用第一种方法（LSConnect），如果设备连接正确，则返回整数LS_OKAY，如果没有连接，则返回LS_PERIPHERAL_NOT_FOUND，但不幸的是，我总是收到错误。
这是我的Java代码：
public class Scanner {
public final static short LS_515_USB = 502;
private static final short hconnect = 0;
public final int LS_OKAY = 0;
public native static int LSConnect(int hWnd, int hlnst, short Peripheral,
short hConnect);
static {
System.loadLibrary("lsApi");
}
/**
* @param args
*/
public static void main(String[] args) {
new Scanner();
System.out.println("connexion établie: "
+ Scanner.LSConnect(0, 0, LS_515_USB, hconnect));
}
}
这是C#定义所有方法的一个例子：
C#定义
命名空间WindowsApplication1
｛
public partial class Form1 : Form
{
// from lsapi.h
[DllImport(@"lsapi.dll")]
internal extern static int LSConnect(int hWnd, int hInst, short Peripheral,ref short hConnect);
[DllImport(@"lsapi.dll")]
internal extern static int LSDisconnect (short hConnect,int hWnd);
[DllImport(@"lsapi.dll")]
internal extern static int LSSaveJPEG( int hwnd, int hImage,int quality, string filename );
[DllImport(@"lsapi.dll")]
internal extern static int LSSaveDIB(int hWnd, int hImage, string filename);
// Parameter Type peripheral
public const short LS_5xx_SCSI = 500;
public const short LS_515_USB = 502;
public const short LS_800_USB = 801;
// ------------------------------------------------------------------------
// REPLY-CODE
// ------------------------------------------------------------------------
public const int LS_OKAY = 0;
// ------------------------------------------------------------------------
// ERRORS
// ------------------------------------------------------------------------
public const int LS_SYSTEM_ERROR = -1;
public const int LS_USB_ERROR = -2;
public const int LS_PERIPHERAL_NOT_FOUND = -3;
public const int LS_HARDWARE_ERROR = -4;
public const int LS_PERIPHERAL_OFF_ON = -5;
public const int LS_RESERVED_ERROR = -6;
public const int LS_BOURRAGE = -7;
public const int LS_PAPER_JAM = -7;
public const int LS_TARGET_BUSY = -8;
public const int LS_INVALID_COMMAND = -9;
public const int LS_DATA_LOST = -10;
public const int LS_COMMAND_IN_EXECUTION_YET = -11;
public const int LS_JPEG_ERROR = -12;
public const int LS_COMMAND_SEQUENCE_ERROR = -13;
public const int LS_PC_HW_ERROR = -14;
public const int LS_IMAGE_OVERWRITE = -15;
public const int LS_INVALID_HANDLE = -16;
public const int LS_NO_LIBRARY_LOAD = -17;
public const int LS_BMP_ERROR = -18;
public const int LS_TIFF_ERROR = -19;
public const int LS_IMAGE_NO_MORE_AVAILABLE = -20;
public const int LS_IMAGE_NO_FILMED = -21;
public const int LS_IMAGE_NOT_PRESENT = -22;
public const int LS_FUNCTION_NOT_AVAILABLE = -23;
public const int LS_DOCUMENT_NOT_SUPPORTED = -24;
public const int LS_BARCODE_ERROR = -25;
public const int LS_INVALID_LIBRARY = -26;
public const int LS_INVALID_IMAGE = -27;
public const int LS_INVALID_IMAGE_FORMAT = -28;
public const int LS_INVALID_BARCODE_TYPE = -29;
public const int LS_OPEN_NOT_DONE = -30;
public const int LS_INVALID_TYPE_COMMAND = -31;
public const int LS_INVALID_CLEARBLACK = -32;
public const int LS_INVALID_SIDE = -33;
public const int LS_MISSING_IMAGE = -34;
public const int LS_INVALID_TYPE = -35;
public const int LS_INVALID_SAVEMODE = -36;
public const int LS_INVALID_PAGE_NUMBER = -37;
public const int LS_INVALID_NRIMAGE = -38;
public const int LS_INVALID_STAMP = -39;
public const int LS_INVALID_WAITTIMEOUT = -40;
public const int LS_INVALID_VALIDATE = -41;
public const int LS_INVALID_CODELINE_TYPE = -42;
public const int LS_MISSING_NRIMAGE = -43;
public const int LS_INVALID_SCANMODE = -44;
public const int LS_INVALID_BEEP = -45;
public const int LS_INVALID_FEEDER = -46;
public const int LS_INVALID_SORTER = -47;
public const int LS_INVALID_BADGE_TRACK = -48;
public const int LS_MISSING_FILENAME = -49;
public const int LS_INVALID_QUALITY = -50;
public const int LS_INVALID_FILEFORMAT = -51;
public const int LS_INVALID_COORDINATE = -52;
public const int LS_MISSING_HANDLE_VARIABLE = -53;
public const int LS_INVALID_POLO_FILTER = -54;
public const int LS_INVALID_ORIGIN_MEASURES = -55;
public const int LS_INVALID_SIZEH_VALUE = -56;
public const int LS_INVALID_FORMAT = -57;
public const int LS_STRINGS_TOO_LONGS = -58;
public const int LS_READ_IMAGE_FAILED = -59;
public const int LS_INVALID_CMD_HISTORY = -60;
public const int LS_MISSING_BUFFER_HISTORY = -61;
public const int LS_INVALID_ANSWER = -62;
public const int LS_OPEN_FILE_ERROR_OR_NOT_FOUND = -63;
public const int LS_READ_TIMEOUT_EXPIRED = -64;
public const int LS_INVALID_METHOD = -65;
public const int LS_CALIBRATION_FAILED = -66;
public const int LS_INVALID_SAVEIMAGE = -67;
public const int LS_INVALID_UNIT = -68;
public const int LS_INVALID_NRWINDOWS = -71;
public const int LS_INVALID_VALUE = -72;
public const int LS_ILLEGAL_REQUEST = -73;
public const int LS_INVALID_NR_CRITERIA = -74;
public const int LS_MISSING_CRITERIA_STRUCTURE = -75;
public const int LS_INVALID_MOVEMENT = -76;
public const int LS_INVALID_DEGREE = -77;
public const int LS_R0TATE_ERROR = -78;
public const int LS_MICR_VALUE_OUT_OF_RANGE = -79;
public const int LS_PERIPHERAL_RESERVED = -80;
public const int LS_INVALID_NCHANGE = -81;
public const int LS_BRIGHTNESS_ERROR = -82;
public const int LS_CONTRAST_ERROR = -83;
public const int LS_INVALID_SIDETOPRINT = -84;
public const int LS_DOUBLE_LEAFING_ERROR = -85;
public const int LS_INVALID_BADGE_TIMEOUT = -86;
public const int LS_INVALID_RESET_TYPE = -87;
public const int LS_MISSING_SET_CALLBACK = -88;
public const int LS_IMAGE_NOT_200_DPI = -89;
public const int LS_DOWNLOAD_ERROR = -90;
public const int LS_INVALID_SORT_ON_CHOICE = -91;
public const int LS_INVALID_FONT = -92;
public const int LS_INVALID_UNIT_SPEED = -93;
public const int LS_INVALID_LENGTH = -94;
public const int LS_SCAN_NETTO_IMAGE_NOT_SUPPORTED= -521;
public const int LS_256_GRAY_NOT_SUPPORTED = -522;
public const int LS_INVALID_PATH = -523;
public const int LS_MISSING_CALLBACK_FUNCTION = -526;
public const int LS_INVALID_OCR_IMAGE_SIDE = -558;
public const int LS_PERIPHERAL_NOT_ANSWER = -599;
public const int LS_INVALID_CONNECTION_HANDLE = -1000;
public const int LS_INVALID_CONNECT_PERIPHERAL = -1001;
public const int LS_PERIPHERAL_NOT_YET_INTEGRATE = -1002;
public const int LS_UNKNOW_PERIPHERAL_REPLY = -1003;
您不能仅通过调用LoadLibrary并定义本机方法（与C#不同）就直接通过JNI调用.dll。您需要用C编写一个"桥接"库（separate.dll），它封装lsapi.dll并将JNI调用约定转换为lsapi调用约定。
我强烈建议使用JNA，而不是编写自己的JNI DLL。使用JNA调用.dll几乎是微不足道的。网络上有很多资源可以提供帮助，在stackoverflow上搜索Java+JNA会得到很多帮助。