UnsatisifiedLink error Problem.

Question

Hi All,
I am encountering with
Exception in thread "main" java.lang.UnsatisfiedLinkError: sample.app.SimpleSerialNative._openSerialPort(Ljava/lang/String;IIII)I
How to solve this issue under windows???
regards,
Viswanadh

Answer 1

Hi,
I think you are talking about the code at http://alumni.media.mit.edu/~benres/simpleserial/ . Well the good people who published that code has given all the resources you need to solve this issue.If you unzip the file you download from their website you will find a folder called "native".Open that folder. In that folder there is a file called "SimpleSerial.dsw".(its visual studio workspace file)
Copy and paste the following into SampleSerial.cpp
#include "simpleserial.h"
#include <windows.h>
// C RunTime Header Files
#include <stdlib.h>
#include <malloc.h>
#include <memory.h>
#include <tchar.h>
#include <stdio.h>
JNIEXPORT jint JNICALL Java_sample_app_SimpleSerialNative__1openSerialPort
(JNIEnv *env, jobject obj, jstring comPort, jint baud, jint dataBits, jint stopBits, jint parity)
     DCB                    dcb;
     HANDLE               hCom;
     DWORD               dwError;
     BOOL               fSuccess;
     COMMTIMEOUTS     timeouts;
     const char          *buffer;
     buffer = env->GetStringUTFChars(comPort, NULL);
     hCom = CreateFile(buffer,
          GENERIC_READ | GENERIC_WRITE,
          0, // comm devices must be opened w/exclusive-access
     NULL, // no security attributes
     OPEN_EXISTING, // comm devices must use OPEN_EXISTING
     0, // not overlapped I/O
          NULL // hTemplate must be NULL for comm devices
     env->ReleaseStringUTFChars(comPort, buffer);
     if (hCom == INVALID_HANDLE_VALUE) {   
          dwError = GetLastError();
          return 0;
// handle error
     fSuccess = GetCommState(hCom, &dcb);
     if (!fSuccess) {    // Handle the error.
          CloseHandle(hCom);
          return 0;
     dcb.fOutxCtsFlow = FALSE;
     dcb.fOutxDsrFlow = FALSE;
     dcb.fDtrControl = DTR_CONTROL_DISABLE;
     dcb.fDsrSensitivity = FALSE;
     dcb.fTXContinueOnXoff = FALSE;
     dcb.fOutX = FALSE;
     dcb.fInX = FALSE;
     dcb.fRtsControl = RTS_CONTROL_DISABLE;
     dcb.XonLim = 0;
     dcb.XoffLim = 0;
     dcb.ByteSize = 8;
     dcb.BaudRate = baud;
     dcb.ByteSize = (unsigned char)dataBits;
     dcb.Parity = (unsigned char)parity;
     dcb.StopBits = (unsigned char)stopBits;
     fSuccess = SetCommState(hCom, &dcb);
     if (!fSuccess) {
          CloseHandle(hCom);
          return 0;
          0,     0,     0          waits forever
          0,     0,     1          20 ms delay
          0,     1,     0          waits forever
          0,     1,     1          waits forever
          1,     0,     0          waits forever
          1,     0,     1          20 ms delay
          1, 1,     0          waits forever
          1,     1,     1          waits forever
          10, 0,     10          20 ms delay
          10, 10, 10          waits forever (VERY SLOW)
          10, 1,     10          ~500 ms
     timeouts.ReadIntervalTimeout = MAXDWORD;
     timeouts.ReadTotalTimeoutMultiplier = 0;
     timeouts.ReadTotalTimeoutConstant = 0;
     timeouts.WriteTotalTimeoutConstant = 0;
     timeouts.WriteTotalTimeoutMultiplier = 0;
     fSuccess = SetCommTimeouts(hCom, &timeouts);
     if (!fSuccess) {
          CloseHandle(hCom);
          return 0;
     FlushFileBuffers(hCom);
     PurgeComm(hCom, PURGE_TXABORT | PURGE_RXABORT | PURGE_TXCLEAR | PURGE_RXCLEAR);
     return (long)hCom;
* Class: SimpleSerial
* Method: _readSerialPort
* Signature: (I)[B
JNIEXPORT jbyteArray JNICALL Java_sample_app_SimpleSerialNative__1readSerialPort
(JNIEnv *env, jobject obj, jint port)
     DWORD          numRead;
     char          buffer[512];          // this should be large enough;
     ReadFile((void*)port, buffer, 512, &numRead, NULL);
//     printf("native sez read %d", (int)numRead);
     jbyteArray          byteArray = env->NewByteArray(numRead);     
     env->SetByteArrayRegion(byteArray, 0, numRead, (signed char*)buffer);
     return byteArray;
* Class: SimpleSerial
* Method: _writeSerialPort
* Signature: (I[B)I
JNIEXPORT jint JNICALL Java_sample_app_SimpleSerialNative__1writeSerialPort
(JNIEnv *env, jobject obj, jint port, jbyteArray bytes)
     DWORD               numWritten;
     int                    size;
     signed char               *buffer;
     size = env->GetArrayLength(bytes);
     if (size == 0) {          // nothing to write
          return 0;
     buffer = env->GetByteArrayElements(bytes, NULL);
     WriteFile((void*)port, buffer, size, &numWritten, NULL);
     FlushFileBuffers((void*)port);
     env->ReleaseByteArrayElements(bytes, buffer, JNI_ABORT);     
     return numWritten;
* Class: SimpleSerial
* Method: _writeSerialPortByte
* Signature: (IB)I
JNIEXPORT jint JNICALL Java_sample_app_SimpleSerialNative__1writeSerialPortByte
(JNIEnv *env, jobject obj, jint port, jbyte byte)
     DWORD          numWritten;
     WriteFile((void*)port, &byte, 1, &numWritten, NULL);
     FlushFileBuffers((void*)port);
     return numWritten;
* Class: SimpleSerial
* Method: _closeSerialPort
* Signature: (I)V
JNIEXPORT void JNICALL Java_sample_app_SimpleSerialNative__1closeSerialPort
(JNIEnv *, jobject, jint port)
     if (port) CloseHandle((void*)port);
And copy and paste the following into simpleserial.h (you can find this in native folder)
#include "jni.h"
/* Header for class SimpleSerialNative */
#ifndef IncludedSimpleSerialNative
#define IncludedSimpleSerialNative
#ifdef __cplusplus
extern "C" {
#endif
* Class: SimpleSerialNative
* Method: _closeSerialPort
* Signature: (I)V
JNIEXPORT void JNICALL Java_sample_app_SimpleSerialNative__1closeSerialPort
(JNIEnv *, jobject, jint);
* Class: SimpleSerialNative
* Method: _openSerialPort
* Signature: (Ljava/lang/String;IIII)I
JNIEXPORT jint JNICALL Java_sample_app_SimpleSerialNative__1openSerialPort
(JNIEnv *, jobject, jstring, jint, jint, jint, jint);
* Class: SimpleSerialNative
* Method: _readSerialPort
* Signature: (I)[B
JNIEXPORT jbyteArray JNICALL Java_sample_app_SimpleSerialNative__1readSerialPort
(JNIEnv *, jobject, jint);
* Class: SimpleSerialNative
* Method: _readSerialPortByte
* Signature: (I)I
JNIEXPORT jint JNICALL Java_sample_app_SimpleSerialNative__1readSerialPortByte
(JNIEnv *, jobject, jint);
* Class: SimpleSerialNative
* Method: _writeSerialPort
* Signature: (I[B)I
JNIEXPORT jint JNICALL Java_sample_app_SimpleSerialNative__1writeSerialPort
(JNIEnv *, jobject, jint, jbyteArray);
* Class: SimpleSerialNative
* Method: _writeSerialPortByte
* Signature: (IB)I
JNIEXPORT jint JNICALL Java_sample_app_SimpleSerialNative__1writeSerialPortByte
(JNIEnv *, jobject, jint, jbyte);
#ifdef __cplusplus
#endif
#endif
Now build the project.(Make sure jni.h and jni_md.h is in the native folder.).Once the build is complete you can find a file called SimpleSerialNative.dll .
Now copy that file into the java source folder where your sample.app package is.And it should work now.