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import com.sun.star.lang.XSingleComponentFactory;
import com.sun.star.lang.XServiceInfo;
import com.sun.star.lang.XInitialization;
import com.sun.star.beans.XPropertySet;
import com.sun.star.uno.XComponentContext;
import com.sun.star.uno.XInterface;
import com.sun.star.uno.UnoRuntime;

import java.lang.reflect.Constructor;


// purpose of this class is to provide a service factory that instantiates
// the services only once (as long as this factory itself exists)
// and returns only reference to that instance.


public class OneInstanceFactory implements
        XSingleComponentFactory,
        XServiceInfo
{
    private final Class    aMyClass;
    private final String   aSvcImplName;
    private final String[] aSupportedSvcNames;
    private XInterface     xInstantiatedService;

    public OneInstanceFactory(
            Class       aMyClass,
            String      aSvcImplName,
            String[]    aSupportedSvcNames )
    {
        this.aMyClass           = aMyClass;
        this.aSvcImplName       = aSvcImplName;
        this.aSupportedSvcNames = aSupportedSvcNames;
        xInstantiatedService = null;
    }


    // XSingleComponentFactory

    public Object createInstanceWithContext( XComponentContext context )
        throws com.sun.star.uno.Exception,
               com.sun.star.uno.RuntimeException
    {
        if (xInstantiatedService == null)
        {
            //!! the here used services all have exact one constructor!!
            Constructor [] aCtor = aMyClass.getConstructors();
            try {
                xInstantiatedService = (XInterface) aCtor[0].newInstance( (Object[])null );
            }
            catch( Exception e ) {
            }

            //!! workaround for services not always being created
            //!! via 'createInstanceWithArguments'
            XInitialization xIni = UnoRuntime.queryInterface(
                XInitialization.class, createInstanceWithContext(context));
            if (xIni != null)
            {
                Object[] aArguments = new Object[]{ null, null };
                if (context != null)
                {
                    XPropertySet xPropSet = UnoRuntime.queryInterface(
                        XPropertySet.class,
                        context.getServiceManager().createInstanceWithContext(
                            "com.sun.star.linguistic2.LinguProperties",
                            context ) );
                    aArguments[0] = xPropSet;
                }
                xIni.initialize( aArguments );
            }
        }
        return xInstantiatedService;
    }

    public Object createInstanceWithArgumentsAndContext( Object[] aArguments, XComponentContext context )
        throws com.sun.star.uno.Exception,
               com.sun.star.uno.RuntimeException
    {
        if (xInstantiatedService == null)
        {
            XInitialization xIni = UnoRuntime.queryInterface(
                XInitialization.class, createInstanceWithContext( context ));
            if (xIni != null)
                xIni.initialize( aArguments );
        }
        return xInstantiatedService;
    }



    // XServiceInfo

    public boolean supportsService( String aServiceName )
        throws com.sun.star.uno.RuntimeException
    {
        boolean bFound = false;
        int nCnt = aSupportedSvcNames.length;
        for (int i = 0;  i < nCnt && !bFound;  ++i)
        {
            if (aServiceName.equals( aSupportedSvcNames[i] ))
                bFound = true;
        }
        return bFound;
    }

    public String getImplementationName()
        throws com.sun.star.uno.RuntimeException
    {
        return aSvcImplName;
    }

    public String[] getSupportedServiceNames()
        throws com.sun.star.uno.RuntimeException
    {
        return aSupportedSvcNames;
    }
}

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