我喜欢让“瘦”字符算作半个字符的想法。简单而良好的近似。
然而，大多数省略的主要问题是（imho）他们在中间砍了字。这是一个考虑单词边界的解决方案（但不涉及像素数学和Swing-API）。
private final static String NON_THIN = "[^iIl1\\.,']";
private static int textWidth(String str) {
return (int) (str.length() - str.replaceAll(NON_THIN, "").length() / 2);
}
public static String ellipsize(String text, int max) {
if (textWidth(text) <= max)
return text;
// Start by chopping off at the word before max
// This is an over-approximation due to thin-characters...
int end = text.lastIndexOf(' ', max - 3);
// Just one long word. Chop it off.
if (end == -1)
return text.substring(0, max-3) + "...";
// Step forward as long as textWidth allows.
int newEnd = end;
do {
end = newEnd;
newEnd = text.indexOf(' ', end + 1);
// No more spaces.
if (newEnd == -1)
newEnd = text.length();
} while (textWidth(text.substring(0, newEnd) + "...") < max);
return text.substring(0, end) + "...";
}
似乎您可以从Java图形上下文的中获得更准确的几何图形FontMetrics。
附录：解决此问题时，可能有助于区分模型和视图。模型是StringUTF-16代码点的有限序列，而视图是一系列字形，以某种字体在某些设备上呈现。
在Java的特定情况下，可以使用JavaSwingUtilities.layoutCompoundLabel()进行翻译。下面的示例拦截了布局调用BasicLabelUI以演示效果。在其他情况下也可以使用实用程序方法，但是FontMetrics必须根据经验确定适当的方法。
替代文字
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.GridLayout;
import java.awt.Rectangle;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import javax.swing.BorderFactory;
import javax.swing.Icon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.border.LineBorder;
import javax.swing.plaf.basic.BasicLabelUI;
/** @see http://stackoverflow.com/questions/3597550 */
public class LayoutTest extends JPanel {
private static final String text =
"A damsel with a dulcimer in a vision once I saw.";
private final JLabel sizeLabel = new JLabel();
private final JLabel textLabel = new JLabel(text);
private final MyLabelUI myUI = new MyLabelUI();
public Layouttest() {
super(new GridLayout(0, 1));
this.setBorder(BorderFactory.createCompoundBorder(
new LineBorder(Color.blue), new EmptyBorder(5, 5, 5, 5)));
textLabel.setUI(myUI);
textLabel.setFont(new Font("Serif", Font.ITALIC, 24));
this.add(sizeLabel);
this.add(textLabel);
this.addComponentListener(new ComponentAdapter() {
@Override
public void componentResized(ComponentEvent e) {
sizeLabel.setText(
"Before: " + myUI.before + " after: " + myUI.after);
}
});
}
private static class MyLabelUI extends BasicLabelUI {
int before, after;
@Override
protected String layoutCL(
JLabel label, FontMetrics fontMetrics, String text, Icon icon,
Rectangle viewR, Rectangle iconR, Rectangle textR) {
before = text.length();
String s = super.layoutCL(
label, fontMetrics, text, icon, viewR, iconR, textR);
after = s.length();
System.out.println(s);
return s;
}
}
private void display() {
JFrame f = new JFrame("LayoutTest");
f.setDefaultCloSEOperation(JFrame.EXIT_ON_CLOSE);
f.add(this);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokelater(new Runnable() {
@Override
public void run() {
new Layouttest().display();
}
});
}
}
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