JNI字符集的转换

    写Java JNI的时候最头痛的莫过于字符集的转换问题，众所周知，Java里字符串是以Unicode编码存储的，而C/C++里大部分是单字节处理，这就涉及到一个转换的问题，下面是两个函数用来在JString到Char*之间的转换：

//author Naven 2003 for both Win32 and Unix os//为了便于使用，无需另连接库，Win32里需自己写双字节memset函数#ifdefined(_WIN32) || defined(__WIN32__)wchar_t *mywmemset(wchar_t *_S, wchar_t _C, size_t _N){    wchar_t *_Su = _S;    for (; 0 < _N; ++_Su, --_N)            *_Su = _C;    return (_S); }#endif//将Java里jstring类型转换成单字节字符串size_t JStringToChars(JNIEnv *env,     const jstring jstr, char *mbstr, const size_t mbslen) {    const jchar *jwstr;     wchar_t *wbuf=0;     size_t nsize=0;     jsize jlen=0;     register int i=0;     memset(mbstr, 0, mbslen);     if( jstr == NULL ) return 0;     jwstr = (*env)->GetStringChars(env, jstr, 0);     jlen = (*env)->GetStringLength(env, jstr);     if( jlen <= 0 ) return 0; #ifdefined(_WIN32) || defined(__WIN32__)    wbuf = (wchar_t *) jwstr;     nsize = wcstombs(mbstr, wbuf, mbslen-1); #else    wbuf = (wchar_t *) malloc((jlen+1)*sizeof(wchar_t));     mywmemset(wbuf, (wchar_t)0, (size_t)(jlen+1));     for( i = 0; i < jlen; i ++ )         wbuf[i] = (wchar_t)jwstr[i];     nsize = wcstombs(mbstr, wbuf, mbslen-1);     free(wbuf); #endif    if( nsize >= 0 && nsize < mbslen )         mbstr[nsize] = 0;         return nsize; }//将单字节字符串转换成Java里可使用的jstring类型size_t CharsToJString(JNIEnv *env,     const char *mbstr, jstring *jstr) {    jchar *jwstr=0;     wchar_t *wcstr=0;     size_t slen=0, nsize=0;     register int i=0;    if( mbstr != NULL )         slen = strlen(mbstr);     if( mbstr == NULL || slen <= 0 ) {         *jstr = (*env)->NewStringUTF(env, "");         return 0;     }    wcstr = (wchar_t *) malloc((slen+1)*sizeof(wchar_t));     mywmemset(wcstr, 0, slen+1);     nsize = mbstowcs(wcstr, mbstr, slen*2);         jwstr = (jchar *) wcstr; #ifdefined(_WIN32) || defined(__WIN32__)#else    for(i =0; i < (int)nsize; i ++) {        jwstr[i] = jwstr[i*2];     }    jwstr[nsize] = 0; #endif    if( nsize <= 0 )         *jstr = (*env)->NewStringUTF(env, "");     else         *jstr = (*env)->NewString(env, jwstr, nsize);     free(wcstr);     return nsize;}