Using dlls in java

Question

can u help me in creating a java application that incorporates a dll created in visual basic or visual c++?

Answer 1

hey, throw your dukes ;-)
here's sample code for JACOB that shows you how easy it is:
import java.math.BigDecimal;
import java.util.*;
//jacob.jar:
import com.jacob.com.*;
import com.jacob.activeX.*;
* Test usage of Visual Basic DLLs in Java with JACOB (JAva-COM Bridge). Requires a DLL in the Java
* Lib Path with classes "TestProject.TestClass" and "TestProject.TestClass2" and the corresponding
* functions/subs.
* <p><b>Links:</b>
* <ul>
* <li><a href="http://danadler.com/jacob/">The JACOB Project: A JAva-COM Bridge</a>
* <li><a href="http://groups.yahoo.com/group/jacob-project/">Yahoo group: jacob-project</a>
* <li><a href="http://www.officecomputertraining.com/vbtutorial/tutpages/page32.asp">VB Dates and Time</a>
* </ul>
public class JacobTest {
     * Test application for JACOB.
     * @param args Not required.
    public static void main(String[] args) {
        System.out.println("Library path: "+System.getProperty("java.library.path"));
        ActiveXComponent activex = null;
        String dllClassName = "TestProject.TestClass";
        long time = System.currentTimeMillis();
        try {
            activex = new ActiveXComponent(dllClassName); //ProgId
            Object o = activex.getObject();
            Variant variant = null;
            System.out.println("\n*** Test function that returns a String:");
            variant = Dispatch.call(o, "getString", "Hello");
            System.out.println("getString('Hello'): "+variant.getString());
            List ml = new ArrayList();
            ml.add("mytest");
            System.out.println("\n*** Test function that returns a String:");
            variant = Dispatch.call(o, "getString", ml.get(0));
            System.out.println("getString('"+ml.get(0)+"'): "+variant.getString());
            System.out.println("\n*** Test function that returns an integer:");
            variant = Dispatch.call(o, "getInteger", new Integer(7));
            System.out.println("getInteger(7): "+variant.getShort());
            System.out.println("\n*** Test function that returns a double:");
            variant = Dispatch.call(o, "getDouble", new Double("12.34"));
            System.out.println("getDouble(12.34): "+variant.getDouble());
            System.out.println("\n*** Test function that returns a boolean:");
            variant = Dispatch.call(o, "getBoolean", new Boolean(true));
            System.out.println("getBoolean(true): "+variant.getBoolean());
            System.out.println("\n*** Test function that returns a date:");
            variant = Dispatch.call(o, "getDate");
            System.out.println("getDate(): "+variant.getDate());
            System.out.println("Java: "+new Date(toMilliseconds(variant.getDate())));
            System.out.println("\n*** Test function that returns a time:");
            variant = Dispatch.call(o, "getTime");
            System.out.println("getTime(): "+variant.getDate());
            System.out.println("Java: "+new Date(toMilliseconds(variant.getDate())));
            System.out.println("\n*** Test function that returns a timestamp:");
            variant = Dispatch.call(o, "getTimestamp");
            System.out.println("getTimestamp(): "+variant.getDate());
            System.out.println("Java: "+new Date(toMilliseconds(variant.getDate())));
            System.out.println("\n*** Test function that returns a timestamp:");
            variant = Dispatch.call(o, "getTimestamp");
            System.out.println("getTimestamp(): "+variant.getDate());
            System.out.println("Java: "+   new Date(toMilliseconds(variant.getDate())));
            System.out.println("\n*** Test function with optional parameter:");
            variant = Dispatch.call(o, "callOptionalParas", "eins", null, "drei");
            System.out.println("callOptionalParas(): "+variant.getString());
            System.out.println("\n*** Test function that returns a 2 dimensional array:");
            variant = Dispatch.call(o, "getArray", "*!*");
            SafeArray array = variant.toSafeArray(false);
            System.out.println("getArray('zwo'): "+array.getString(0,2));
            System.out.println("\n*** Test function with more than 8 parameters:");
            Object[] paras = new String[] {"1", "2", "3", "4", "five", "six", "seven", "eight", "nine", "ten"};
            variant = Dispatch.callN(o, "callNParas", paras);
            System.out.println("callNParas(..."+paras[9]+"): "+variant.getString());
            System.out.println("\n*** Test function that returns another COM object:");
            variant = Dispatch.call(o, "getTestClass2", "Test Object 1");
            Object class2 = variant.getDispatchRef();
            variant = Dispatch.call(class2, "getValue", "myPara!");
            System.out.println("getTestClass2().getValue('myPara'): "+variant);
//            System.out.println("\n*** Open a Microsoft Word document:");
//            ActiveXComponent oWord = new ActiveXComponent("Word.Application");
//            oWord.setProperty("Visible", new Variant(true));
//            Object oDocuments = oWord.getProperty("Documents").toDispatch();
//            Object oDocument = Dispatch.call(oDocuments, "Open", "E:/temp/TestDoc.doc").toDispatch();
//            Object oSelection = oWord.getProperty("Selection").toDispatch();
            System.out.println("\n*** Test function with new COM object parameter:");
            ActiveXComponent com2 = new ActiveXComponent("TestProject.TestClass2"); //ProgId
//            Dispatch d2 = (Dispatch) com2.getObject();
//            Variant v = new Variant(d2);
//            Dispatch vp = v.toDispatch();
            variant = Dispatch.call(o, "callWithComPara", com2);
            System.out.println("callWithComPara(): "+variant.getString());
            System.out.println("\nDuration [ms]: "+(System.currentTimeMillis() - time));
        } catch (Throwable t) {
            System.err.println("ERROR with ActiceX component '"+dllClassName+"': "+t);
    }//main()
     * Convert a Visual Basic time double value (e.g. from functions Date(), Time(), Now()) to a Java long value (milliseconds).
     * Visual Basic time values are based to 30.12.1899, Java time values are based to 1.1.1970 (= 0 milliseconds).
     * The difference is added to the Visual Basic value to get the corresponding Java value. The Visual Basic double value reads:
     * <day count delta since 30.12.1899>.<1 day percentage fraction>, e.g. "38100.6453" means: 38100 days since 30.12.1899
     * plus (24 hours * 0.6453). Example usage: <code>Date javaDate = new Date(toMilliseconds(vbDate));</code>.
     * @param vbTimestamp Time value from Visual Basic.
     * @return Number of milliseconds since 1.1.1970.
    static public long toMilliseconds(double vbTimestamp) {
        long result = 0;
        final long vbZeroTime = -2209165200000L; //30.12.1899 00:00:00 in milliseconds
        final long oneDay = 86400000; //1 day in milliseconds (24 * 60 * 60 * 1000)
        BigDecimal bd = new BigDecimal(""+vbTimestamp);
        long dayCount = bd.longValue(); //value left of point; number of days since 30.12.1899
        BigDecimal tp = bd.subtract(new BigDecimal(""+dayCount)); //fractional part is factor for 1 day (e.g. 0.5 => 12 hours)
        long date = vbZeroTime + (dayCount * oneDay); //compute java date
        //avoid problems with daylight savings time by setting time to 00:00:00 :
        GregorianCalendar dateCal = new GregorianCalendar();
        dateCal.setTimeInMillis(date);
        dateCal.set(Calendar.HOUR, 0);
        dateCal.set(Calendar.HOUR_OF_DAY, 0);
        dateCal.set(Calendar.MINUTE, 0);
        dateCal.set(Calendar.SECOND, 0);
        dateCal.set(Calendar.MILLISECOND, 0);
        date = dateCal.getTimeInMillis();
        long time = (long) (oneDay * tp.doubleValue()); //compute java time
        result = date + time;
        return result;
    }//toMilliseconds()
}//JacobTest()