java - StyledEditorKit 文本对齐无法正常工作

Question

我正在尝试在 Java 生成的 html 文档中实现用户可选择的文本对齐方式。我已经尝试过:

JMenuItem leftAlignMenuItem = 
  new JMenuItem(new StyledEditorKit.AlignmentAction("Left Align", StyleConstants.ALIGN_LEFT));
JMenuItem centerMenuItem = 
  new JMenuItem(new StyledEditorKit.AlignmentAction("Center", StyleConstants.ALIGN_CENTER));
JMenuItem rightAlignMenuItem = 
  new JMenuItem(new StyledEditorKit.AlignmentAction("Right Align", StyleConstants.ALIGN_RIGHT));

以及该主题的各种变体。选择菜单项会使文本在文本 Pane 中正确对齐，并将适当的 html 标记添加到保存的文档中。问题是，添加标签后，单击另一个对齐菜单项不会更改它，因此无法多次更改默认(左)文本对齐方式并保存更改。

我知道我不是第一个遇到此问题的人，但到目前为止我还没有找到任何解决方案，因此我们将不胜感激。

这是我的“M”CVE，不幸的是它仍然很大，但我无法删除更多代码，否则它不会演示问题:

package aligntest;

import java.awt.*;
import java.awt.event.*;

import javax.swing.*;
import javax.swing.text.*;
import javax.swing.text.html.HTMLDocument;
import javax.swing.text.html.HTMLEditorKit;
import javax.swing.JFrame;

public class AlignTest extends JFrame implements ActionListener {

    private HTMLDocument doc; // Stores the formatted text.
    private JTextPane textPane = new JTextPane(); // The Pane itself.
    String FilePath = "";  // Stores the file path.

        public AlignTest() { // This method is called automatically when the app is launched.
            HTMLEditorKit editorKit = new HTMLEditorKit();
            doc = (HTMLDocument)editorKit.createDefaultDocument();  
            init(); // Calls interface method below.
    }

    public static void main(String[] args) {
        AlignTest editor = new AlignTest();
    }
        public void init(){

            JMenuBar menuBar = new JMenuBar();
            getContentPane().add(menuBar, BorderLayout.NORTH);
            JMenu fileMenu = new JMenu("File"); 
            JMenu alignMenu = new JMenu("Text Align");

            menuBar.add(fileMenu);
            menuBar.add(alignMenu);

            JMenuItem openItem = new JMenuItem("Open"); //
            JMenuItem saveItem = new JMenuItem("Save"); //

            openItem.addActionListener(this);
            saveItem.addActionListener(this);

            fileMenu.add(openItem);
            fileMenu.add(saveItem);

            JMenuItem leftAlignMenuItem = new JMenuItem(new StyledEditorKit.AlignmentAction("Left Align", StyleConstants.ALIGN_LEFT));
            JMenuItem centerMenuItem = new JMenuItem(new StyledEditorKit.AlignmentAction("Center", StyleConstants.ALIGN_CENTER));
            JMenuItem rightAlignMenuItem = new JMenuItem(new StyledEditorKit.AlignmentAction("Right Align", StyleConstants.ALIGN_RIGHT));

            leftAlignMenuItem.setText("Left");
            centerMenuItem.setText("Center");
            rightAlignMenuItem.setText("Right");

            alignMenu.add(leftAlignMenuItem);
            alignMenu.add(centerMenuItem);
            alignMenu.add(rightAlignMenuItem);

            textPane = new JTextPane(doc); // Create object from doc and set this as value of textPane.
            textPane.setContentType("text/html"); // textPane holds html.
            JScrollPane scrollPane = new JScrollPane(textPane); // textPane in JScrollPane to allow scrolling if more text than space.
            Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize(); // Get screen size to use below.
            Dimension scrollPaneSize = new Dimension(1*screenSize.width/2,1*screenSize.height/2); // Together with next line, sets dimensions of textPane relative to screen size.
            scrollPane.setPreferredSize(scrollPaneSize);
            getContentPane().add(scrollPane, BorderLayout.SOUTH);

            pack();
            setLocationRelativeTo(null);        
            show(); // Actually displays the interface.

        }

        public void actionPerformed(ActionEvent ae) { // Method called with action commands from interface objects above.  Which action depends on the text of the interface element.
            String actionCommand = ae.getActionCommand();           
        if (actionCommand.compareTo("Open") == 0){ // Calls method when action command received.
            openDocument();
        } else if (actionCommand.compareTo("Save") == 0){
            saveDocument();
                }
        }

        public void saveDocument(){

            String FP = FilePath;  // This paragraph calls Save As instead of Save if file not already saved.
            String unsaved = "";
            int saved = FP.compareTo(unsaved);
            if (saved == 0) {
                saveDocumentAs();
            } else {
                save();
            }
        }

        public void saveDocumentAs(){                
            JFileChooser SaveDialog = new javax.swing.JFileChooser();
            int returnVal = SaveDialog.showSaveDialog(this);

            if (returnVal == JFileChooser.APPROVE_OPTION) {
                java.io.File saved_file = SaveDialog.getSelectedFile();
                FilePath = saved_file.toString();

                save();
            }
        }

        public void save(){
            try {
                WriteFile objPane = new WriteFile(FilePath, false);
                String PaneText = textPane.getText();  // Gets text from Title Pane.
                objPane.writeToFile(PaneText);
            }
            catch (Exception ex) {
            }
        }

        public void openDocument(){

            JFileChooser OpenDialog = new javax.swing.JFileChooser(); // Creates file chooser object.
            int returnVal = OpenDialog.showOpenDialog(this);  // Defines 'returnVal' according to what user clicks in file chooser.

            if (returnVal == JFileChooser.APPROVE_OPTION) { // Returns value depending on whether user clicks 'yes' or 'OK' etc.
                java.io.File file = OpenDialog.getSelectedFile(); // Gets path of selected file.
                FilePath = file.toString( ); // Converts path of selected file to String.

// The problem seems to be related to the code that starts here...
                try {
                    ReadFile readPane = new ReadFile(FilePath);  // Creates "readPane" object from "FilePath" string, using my ReadFile class.
                    String[] aryPane = readPane.OpenFile();  // Creates string array "aryPane" from "readPane" object.

                    int i;  // Creates integer variable "i".
                    String PaneText = "";

                    for (i=0; i < aryPane.length; i++) {  //  Creates a for loop with starting "i" value of 0, adding 1 to i each time round and ending when i = the number of lines in the aryLines array.
                        PaneText = PaneText + aryPane[i];  //  Add present line to "PaneText".
                    }
                    textPane.setText(PaneText);  // Displays "PaneText" in "TextPane".

                } catch (Exception ex) {
// and ends here.  This code also calls ReadFile, so code in that class may be at fault.

                }
                }
            }
}

它还必须调用以下两个类中的方法才能工作:

package aligntest;

import java.io.IOException;
import java.io.FileReader;
import java.io.BufferedReader;

public class ReadFile {

    private String path;

    public ReadFile(String file_path) {
        path = file_path;
    }

    public String[] OpenFile() throws IOException {

        FileReader fr = new FileReader(path);
        BufferedReader textReader = new BufferedReader(fr);

        int numberOfLines = readLines( );
        String[] textData = new String[numberOfLines];

        int i;

        for (i=0; i < numberOfLines; i++) {
            textData[i] = textReader.readLine();
        }

        textReader.close( );
            return textData;
    }


    int readLines() throws IOException {

        FileReader file_to_read = new FileReader(path);
        BufferedReader bf = new BufferedReader(file_to_read);

        String aLine;
        int numberOfLines = 0;

        while ((aLine = bf.readLine()) != null) {
            numberOfLines++;
        }
        bf.close();

        return numberOfLines;
    }

}

&

package aligntest;

import java.io.File;
import java.io.FileWriter;
import java.io.PrintWriter;
import java.io.IOException;

public class WriteFile {

    private String path;
    private boolean append_to_file = false;

    public WriteFile(String file_path) {
        path = file_path;
    }

    public WriteFile(String file_path, boolean append_value) {
        path = file_path;
    }

    public WriteFile(File SectionPath, boolean success) {
        throw new UnsupportedOperationException("Not yet implemented");
    }
    public void writeToFile( String textLine ) throws IOException {
        FileWriter write = new FileWriter(path, append_to_file);
        PrintWriter print_line = new PrintWriter(write);

        print_line.printf( "%s" + "%n" , textLine);

        print_line.close();
}
}

问题似乎与打开文档(第 126 - 138 行)或“ReadFile”类有关:在另一个程序中查看保存的文件时，我可以看到标签正在更改，直到文档关闭，然后使用“AlignTest”再次打开。此后，任何对齐更改都不会反射(reflect)在 html 中。

希望有人能帮忙。

编辑:这是“AlignTest”生成的一些 html。如果将其粘贴到文本文件中，然后在“AlignTest”中打开，它应该会重现该问题:“AlignTest”无法更改对齐标记。

<html>
  <head>
    <meta id="_moz_html_fragment">

  </head>
  <body>
    <p align="right" style="margin-top: 0pt">
      Another
    </p>
  </body>
</html>

Answer 1

事实证明这比我想象的要困难。让我解释一下幕后发生的事情，然后我将给出一些场景。

AlignmentAction的操作调用文档的 setParagraphAttributes与 boolean replace设置为false 。在 setParagraphAttributes ，给定属性 ( Alignment.XXX ) 通过 MutableAttributeSet.addAttributes 添加到段落标记的当前属性列表中。效果如下:

1. 如果段落标签没有任何对齐指令，则 HTML align="xxx"被添加。文件将使用此新属性保存。
2. 如果段落标记只有 HTML 属性，则会添加内联 CSS 属性:text-align=xxx 。文件仅保存 HTML 属性(CSS 属性被丢弃，我不知道为什么，可能是 " 需要替换为 ' )。
3. 如果段落标记具有 HTML 和 CSS 属性，则修改 CSS 属性。文件仅保存为 HTML 格式。
4. 如果段落标记只有 CSS 属性，则会对其进行修改。该文件具有从 CSS 属性转换而来的新 HTML 属性。

总结就是，由于某种原因，无论运行时存在哪些属性，都只能保存 HTML 属性。由于它没有被修改，所以必须先将其删除，然后再添加新属性。可能需要使用不同的编写器。

解决方案的一种尝试是创建您自己的对齐操作并将替换值设置为 true 。问题是它替换了整个段落元素:

<html>
  <head>
    <meta id="_moz_html_fragment">

  </head>
  <body>
    <body align="center">
      Another
    </body>
  </body>
</html>

您需要做的是访问该元素并“手动”替换属性。创建一个扩展 HTMLDocument 的类和@override它的setParagraphAttributes使其包含行

// attr is the current attribute set of the paragraph element
attr.removeAttribute(HTML.Attribute.ALIGN); // remove the HTML attribute

之前

attr.addAttributes(s); // s is the given attributes containing the Alignment.XXX style.

然后保存文件将按照上述 1-4 种情况保持正确对齐。

最终您将需要使用 HTML 解析器，例如 jsoup ;只是 Google 的 Java HTML 解析器。另请参阅Which HTML Parser is the best?