用swing如何实现QQ聊天气泡效果

public class JIMSendTextPane extends JTextPane {  
  
    // 内部类  
    // 以下内部类全都用于实现自动强制折行  
  
    private class WarpEditorKit extends StyledEditorKit {  
  
        private ViewFactory defaultFactory = new WarpColumnFactory();  
  
        @Override  
        public ViewFactory getViewFactory() {  
            return defaultFactory;  
        }  
    }  
  
    private class WarpColumnFactory implements ViewFactory {  
  
        public View create(Element elem) {  
            String kind = elem.getName();  
            if (kind != null) {  
                if (kind.equals(AbstractDocument.ContentElementName)) {  
                    return new WarpLabelView(elem);  
                } else if (kind.equals(AbstractDocument.ParagraphElementName)) {  
                    return new ParagraphView(elem);  
                } else if (kind.equals(AbstractDocument.SectionElementName)) {  
                    return new BoxView(elem, View.Y_AXIS);  
                } else if (kind.equals(StyleConstants.ComponentElementName)) {  
                    return new ComponentView(elem);  
                } else if (kind.equals(StyleConstants.IconElementName)) {  
                    return new IconView(elem);  
                }  
            }  
  
            // default to text display  
            return new LabelView(elem);  
        }  
    }  
  
    private class WarpLabelView extends LabelView {  
  
        public WarpLabelView(Element elem) {  
            super(elem);  
        }  
  
        @Override  
        public float getMinimumSpan(int axis) {  
            switch (axis) {  
                case View.X_AXIS:  
                    return 0;  
                case View.Y_AXIS:  
                    return super.getMinimumSpan(axis);  
                default:  
                    throw new IllegalArgumentException("Invalid axis: " + axis);  
            }  
        }  
    }  
  
    // 本类  
  
    // 构造函数  
    public JIMSendTextPane() {  
        super();  
        this.setEditorKit(new WarpEditorKit());  
    }  
}