JNA mapping LPCSTR on windows platform

Question

I am working on call one DLL api for C/C++ with JNA. The function API in DLL is short DKT_init(LPCSTR name). I made the corresponding java method as public short DKT_init(String name); But when I call it, the DLL API return a parameter error. I wonder how to map LPCSTR in JNA? As LPCSTR is cons char * but String is char *.

Answer 1

String is the appropriate mapping for LPCSTR. JNA will convert the modified UTF16 characters into a NUL-terminated buffer of bytes using the default platform encoding.

You might try passing in an explicit byte array instead (using the suggested alternate method mapping above), which would eliminate the potential of an incorrect encoding issue, eg

byte[] arg = { (byte)'f', (byte)'o', (byte)'o', (byte)0 };

You can alter the encoding used by setting the system property "jna.encoding".

You should also eliminate the possibility that "LPCSTR" is actually an incorrect type; if the function is expecting a buffer it can write to, String will not work, and if it's actually LPTCSTR and you're using UNICODE, then you need to pass a WString instead.

Answer 2

Have you tried mapping it to a byte array, like this:

short DKT_INIT(byte [] nameAsByteArray);
//now you should be able to obtain it like this:
System.out.println(new String(nameAsByteArray).trim());