如何优化使用Singleton扩展JLabel的类

Question

我有一个扩展JLabel的类。这是班级：

public class LabelFormat extends JLabel {
    public LabelFormat(String string){
        Font myFont=UtilitySwing.getLabelFont();
        this.setText(string);
        this.setFont(myFont);
    }
}

这是UtilitySwing类中的方法：

public static Font getLabelFont(){
    Toolkit t = Toolkit.getDefaultToolkit();
    Dimension screenSize = t.getScreenSize();

    double width = screenSize.getWidth();
    double height= screenSize.getHeight();
    Font myFont;
    if ((width == 1600.0) && (height == 900.0) || 
            (width == 1440.0) && (height == 900.0) || 
            (width == 1280) && (height== 800) || 
            ((width == 1280) && (height== 768)))
    {
        myFont = new Font("Century Gothic", Font.PLAIN, 14);
    }
    else if((width==1024) && (height ==600))
    {
        myFont = new Font("Century Gothic", Font.PLAIN, 12);
    }
    else if ((width == 1024) && (height== 768))
    {
        myFont = new Font("Century Gothic", Font.PLAIN, 12);
    }
    else if ((width == 800) && (height== 600))
    {
        myFont = new Font("Century Gothic", Font.PLAIN, 11);
    }
    else{
        myFont = new Font("Century Gothic", Font.PLAIN, 11);
    }   
    return myFont;
}

所以这个课程找到了，但对我来说代码不是很有效，因为如果我创建了5个标签我就有这个：

LabelFormat label1 = new LabelFormat("Pippo");
LabelFormat label2 = new LabelFormat("Pippo");
LabelFormat label3 = new LabelFormat("Pippo");
LabelFormat label4 = new LabelFormat("Pippo");
LabelFormat label5 = new LabelFormat("Pippo");

使用此代码，我调用UtilitySwing类5次来计算Label的字体。我想如果可以使用单例模式调用一次UtilitySwing来计算字体。

为此，也可以在主类中创建Font并将其设置为所有Label，但我想创建一个jar lib，用户无需担心设置字体。

Answer 1

你可以......

在创建标签之前调用UtilitySwing.getLabelFont()并设置字体属性...

Font font = UtilitySwing.getLabelFont();
LabelFormat label1 = new LabelFormat("Pippo");
label1.setFont(font);
//...

但我会尝试使用工厂方法或循环来使这更容易......

Font font = UtilitySwing.getLabelFont();
LabelFormat label1 = createFormatLabel("Pippo", font);

你可以......

使用UIManager.put("Label.font", UtilitySwing.getLabelFont());设置所有JLabel使用的字体，假设您希望更改为全局

这会让您想到可能会创建一个自定义外观代理，您可以提供更好的控制权并仅影响LabelFormat个实例

你可以......

缓存结果......

private static Map<Dimension, Font> mapFonts = new HashMap<>(25);

public static Font getLabelFont() {
    Toolkit t = Toolkit.getDefaultToolkit();
    Dimension screenSize = t.getScreenSize();

    Font font = mapFonts.get(screenSize);
    if (font == null) {

        double width = screenSize.getWidth();
        double height = screenSize.getHeight();
        if ((width == 1600.0) && (height == 900.0)
                        || (width == 1440.0) && (height == 900.0)
                        || (width == 1280) && (height == 800)
                        || ((width == 1280) && (height == 768))) {
            font = new Font("Century Gothic", Font.PLAIN, 14);
        } else if ((width == 1024) && (height == 600)) {
            font = new Font("Century Gothic", Font.PLAIN, 12);
        } else if ((width == 1024) && (height == 768)) {
            font = new Font("Century Gothic", Font.PLAIN, 12);
        } else if ((width == 800) && (height == 600)) {
            font = new Font("Century Gothic", Font.PLAIN, 11);
        } else {
            font = new Font("Century Gothic", Font.PLAIN, 11);
        }

        if (font != null) {
            mapFonts.put(screenSize, font);
        }
    }
    return font;
}

如果您认为默认屏幕尺寸可能会改变或......

private static Font font;

public static Font getLabelFont() {

    if (font == null) {

        Toolkit t = Toolkit.getDefaultToolkit();
        Dimension screenSize = t.getScreenSize();

        double width = screenSize.getWidth();
        double height = screenSize.getHeight();
        if ((width == 1600.0) && (height == 900.0)
                        || (width == 1440.0) && (height == 900.0)
                        || (width == 1280) && (height == 800)
                        || ((width == 1280) && (height == 768))) {
            font = new Font("Century Gothic", Font.PLAIN, 14);
        } else if ((width == 1024) && (height == 600)) {
            font = new Font("Century Gothic", Font.PLAIN, 12);
        } else if ((width == 1024) && (height == 768)) {
            font = new Font("Century Gothic", Font.PLAIN, 12);
        } else if ((width == 800) && (height == 600)) {
            font = new Font("Century Gothic", Font.PLAIN, 11);
        } else {
            font = new Font("Century Gothic", Font.PLAIN, 11);
        }           
    }
    return font;
}

如果您不在乎并且只是想节省时间而不是一次又重复决策过程......