JTextPane - 获取组件值

Question

我有JTextPane，其中插入2个JLabel。如果单击任何标签，则会将内容从AAA更改为单击。

此代码遍历JTextPane中的元素：

        for(int i = 0; i < tp.getDocument().getLength(); i++) {
            System.out.println(((StyledDocument) tp.getDocument()).getCharacterElement(i));
        }

如何访问标签以将“点击”“AAAA”打印到标准输出？

package texteditor;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

import javax.swing.BorderFactory;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JPopupMenu;
import javax.swing.JScrollPane;
import javax.swing.JTextPane;
import javax.swing.border.BevelBorder;
import javax.swing.border.TitledBorder;
import javax.swing.text.BadLocationException;
import javax.swing.text.StyledDocument;
import javax.swing.JButton;

public class JTextPaneExample extends JPanel {

    private JTextPane tp;

    public JTextPaneExample() {
        setLayout(new BorderLayout(0, 0));

        JPanel panel = new JPanel();
        panel.setBorder(new TitledBorder(null, "Text Content", TitledBorder.LEADING, TitledBorder.TOP, null, null));
        add(panel, BorderLayout.CENTER);
        panel.setLayout(new BorderLayout(0, 0));

        JScrollPane scrollPane = new JScrollPane();
        panel.add(scrollPane, BorderLayout.CENTER);

        tp = new JTextPane();
        tp.setEditable(false);
        scrollPane.setViewportView(tp);

        JLabel lbl = new JLabel("AAAA ");
        lbl.setOpaque(true);
        lbl.setBorder(BorderFactory.createLineBorder(Color.black, 1));
        lbl.addMouseListener(new LabelAdapter2(lbl));
        tp.insertComponent(lbl);

        lbl = new JLabel("BBBB ");
        lbl.setOpaque(true);
        lbl.setBorder(BorderFactory.createLineBorder(Color.black, 1));
        lbl.addMouseListener(new LabelAdapter2(lbl));
        tp.insertComponent(lbl);

        JButton btnNewButton = new JButton("Write content");
        btnNewButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                iterateOverContent(tp);
            }
        });
        panel.add(btnNewButton, BorderLayout.SOUTH);
    }

    private void iterateOverContent(JTextPane tp2) {
            for(int i = 0; i < tp.getDocument().getLength(); i++) {
                System.out.println(((StyledDocument) tp.getDocument()).getCharacterElement(i));
            }
    }

    private class LabelAdapter2 extends MouseAdapter {
        private JLabel lblNewLabel;

        public LabelAdapter2(JLabel lbl) {
            this.lblNewLabel = lbl;
        }


        public void mouseClicked(MouseEvent evt) {
            lblNewLabel.setText("clicked");
        }
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame("GoBoard");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().add(new JTextPaneExample());
        frame.setPreferredSize(new Dimension(400, 400));
        frame.pack();
        frame.setVisible(true);
    }
}

Answer 1

我查看了你的问题并找到了解决方案：

只需用你的方法替换你的方法迭代TextPane的元素：

private void iterateOverContent(JTextPane tp2) {
        for(int i = 0; i < tp.getDocument().getLength(); i++) {
            Element elem = ((StyledDocument) tp.getDocument()).getCharacterElement(i);
            AttributeSet as = elem.getAttributes();
            if (as.containsAttribute(AbstractDocument.ElementNameAttribute, StyleConstants.ComponentElementName)) {
                if(StyleConstants.getComponent(as) instanceof JLabel) {
                    JLabel myLabel = (JLabel)StyleConstants.getComponent(as);
                    System.out.println(myLabel.getText());
                }
            }
            System.out.println(((StyledDocument) tp.getDocument()).getCharacterElement(i));
        }
}

正如你所看到的，我首先将元素保存到一个新变量然后读出所有属性（是的，代码可能会更短，但这样更明确 - 我希望:-)） 之后，我们检查属性是否说明该元素是一个组件。

然后是重要的部分：我们可以通过StyleConstants.getComponent方法从属性集中获取一个Component。

最后只是进行一些健全性检查，看看我们是否真的可以将它强制转换为JLabel。

祝你好运， 大卫