java - 样式文本未从 JTextPane 正确保存

Question

我正在尝试实现一个小型 HTML 编辑器，允许将前景色和背景色应用于部分文本。我想以 HTML 格式存储文本，并将颜色信息保留在文件中。当使用不同样式(样式定义前景色和背景色信息)编辑文本时，我当前的实现可以正常运行。但是，当将编辑后的文档存储在文件中时，我得到的 HTML 结构不正确，并且使用特定样式输入的文本部分丢失。这是我的代码:

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Enumeration;
import java.util.Vector;

import javax.swing.AbstractAction;
import javax.swing.DefaultComboBoxModel;
import javax.swing.JComboBox;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JOptionPane;
import javax.swing.JTextPane;
import javax.swing.JToolBar;
import javax.swing.text.AttributeSet;
import javax.swing.text.MutableAttributeSet;
import javax.swing.text.SimpleAttributeSet;
import javax.swing.text.Style;
import javax.swing.text.html.HTMLDocument;
import javax.swing.text.html.HTMLEditorKit;
import javax.swing.text.html.StyleSheet;

public class SimpleEditor extends JFrame {

    private static final long   serialVersionUID = 1L;
    private final JTextPane   textPane;
    private final HTMLEditorKit edtKit;
    private final HTMLDocument  doc;
    private final StyleSheet predefStyles;

    public static void main(String[] args) {
        final SimpleEditor editor = new SimpleEditor();
        editor.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        editor.setVisible(true);
    }

    public SimpleEditor() {
        super("Very Simple HTML Editor");
        textPane = new JTextPane();
        edtKit = new HTMLEditorKit();
        textPane.setEditorKit(edtKit);
        predefStyles = new StyleSheet();
        predefStyles.addRule("MyStyle1 { color:#cc0000; background-color:silver }\n" +
                             "MyStyle2 { color:#0000cc; background-color:aqua }");
        doc = new HTMLDocument(predefStyles);
        textPane.setDocument(doc);

        final Container content = getContentPane();
        content.add(textPane, BorderLayout.CENTER);
        content.add(createToolBar(), BorderLayout.NORTH);
        setJMenuBar(createMenuBar());
        setSize(500, 240);
    }

    private JToolBar createToolBar() {
        final Vector<String> styleNames = new Vector<String>();
        final Enumeration<?> names = predefStyles.getStyleNames();
        while (names.hasMoreElements()) {
            styleNames.add((String) names.nextElement());
        }
        final DefaultComboBoxModel<String> stylesModel =
                new DefaultComboBoxModel<String>(styleNames);
        final JComboBox<String> cbStyleSel = new JComboBox<String>(stylesModel);
        final JToolBar bar = new JToolBar();
        cbStyleSel.setEditable(false);
        cbStyleSel.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                e.getSource();
                @SuppressWarnings("unchecked")
                final JComboBox<CondStyle> cboStyleSel =
                          (JComboBox<CondStyle>) e.getSource();
                final String selItem = (String) cboStyleSel.getSelectedItem();
                final Style style = textPane.getStyle(selItem);
                textPane.setCharacterAttributes(extractStyleAttribs(style), true);
                SimpleEditor.this.requestFocus();
            }
        });
        bar.add(cbStyleSel);
        return bar;
    }

    /**
     * Extracts the style attributes except the style's name
     * @param aStyle The style to be processed
     * @return The visual attributes extracted from the style
     */
    AttributeSet extractStyleAttribs(Style aStyle) {
        final MutableAttributeSet attribs = new SimpleAttributeSet();
        final Enumeration<?> attribNames = aStyle.getAttributeNames();
        while (attribNames.hasMoreElements()) {
            final Object attribName = attribNames.nextElement();
            if (attribName == Style.NameAttribute) {
                continue;
            }
            attribs.addAttribute(attribName, aStyle.getAttribute(attribName));
        }
        return attribs;
    }

    private JMenuBar createMenuBar() {
        final JMenuBar menubar = new JMenuBar();
        final JMenu mnuFile = new JMenu("File");
        menubar.add(mnuFile);
        final ExitAction actSave = new ExitAction();
        mnuFile.add(actSave);
        return menubar;
    }

    class ExitAction extends AbstractAction {
        private static final long serialVersionUID = 1L;
        public ExitAction() {
            super("Save & Exit");
        }
        @Override
        public void actionPerformed(ActionEvent ev) {
            final JFileChooser chooser = new JFileChooser();
            if (chooser.showSaveDialog(SimpleEditor.this) != 
                JFileChooser.APPROVE_OPTION)
                return;
            final File file = chooser.getSelectedFile();
            if (file == null)
                return;
            FileWriter writer = null;
            try {
                writer = new FileWriter(file);
                textPane.write(writer);
            } catch (final IOException ex) {
                JOptionPane.showMessageDialog(SimpleEditor.this,
                                              "File Not Saved", "ERROR",
                                              JOptionPane.ERROR_MESSAGE);
            } finally {
                if (writer != null) {
                    try {
                        writer.close();
                    } catch (final IOException x) {
                    }
                }
            }
            System.exit(0);
        }
    }
}

这是应用程序的屏幕截图，其中输入了一些样式文本:

保存文档 ( textPane.write(writer); ) 时创建的 HTML 文件结构不正确。 <body> ... </body>部分如下所示:

<body>
    <p style="margin-top: 0">
      default text
    </p>
    <p style="margin-top: 0">
      <font color="#cc0000"><p style="background-color: silver">
</font>    </p>
    <p style="margin-top: 0">
      <font color="#0000cc"><p style="background-color: aqua">
</font>    </p>
    <p style="margin-top: 0">
      <font color="#333333" face="Dialog" size="3"><p FONT_ATTRIBUTE_KEY="javax.swing.plaf.FontUIResource[family=Dialog,name=Dialog,style=plain,size=12]">
</font>    </p>
</body>

很明显，生成的 HTML 代码不正确。里面<p>元素一个新<font>创建的元素定义了样式的前景色。然后另一个<p>创建具有背景颜色定义的元素。但文字不见了。然后而不是关闭 </p>标记结束 </font>标签后面是 </p>标签关闭外部 <p>元素。我究竟做错了什么？

Answer 1

经过大量研究，我找到了解决问题的简单方法。请参阅here .