如何在iText5中绘制圆的阴影

Document document = new Document();
PdfWriter writer = PdfWriter.getInstance(document, new FileOutputStream("output.pdf"));
document.open();

PdfContentByte contentByte = writer.getDirectContent();
contentByte.circle(x, y, radius);

PdfGState gState = new PdfGState();
gState.setShadow(new BaseColor(0, 0, 0), 4, -4);
gState.setFillOpacity(0.5f);
contentByte.setGState(gState);

contentByte.fill();
document.close();

import com.itextpdf.text.Document;
import com.itextpdf.text.pdf.PdfContentByte;
import com.itextpdf.text.pdf.PdfGState;
import com.itextpdf.text.pdf.PdfWriter;

import java.io.FileOutputStream;

public class CircleShadowExample {
    public static void main(String[] args) {
        try {
            Document document = new Document();
            PdfWriter writer = PdfWriter.getInstance(document, new FileOutputStream("output.pdf"));
            document.open();

            PdfContentByte contentByte = writer.getDirectContent();
            contentByte.circle(250, 250, 100);

            PdfGState gState = new PdfGState();
            gState.setShadow(new BaseColor(0, 0, 0), 4, -4);
            gState.setFillOpacity(0.5f);
            contentByte.setGState(gState);

            contentByte.fill();
            document.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}