java - 从文档监听器返回一个值

Question

我有 2 个 Java 类(class)。一旦将文档监听器添加到文档(HTMLDoc)。另一个是实现 DocumentListener 的类。

我希望能够向此类返回一个值，以便我知道文档何时更改，这样我就可以删除粘贴到其中并导致 JTextPane 出现问题的不需要的 html。

doc = (HTMLDocument) kit.createDefaultDocument();
//setContentType("text/html");
doc.addDocumentListener(new CTextPaneListener());

这是监听器类

public class CTextPaneListener implements DocumentListener
{

    // Gives notification that an attribute or set of attributes changed.
    @Override public void  changedUpdate(DocumentEvent e)
    {
        //System.out.println("DEBUG: changedUpdate() called");
    }

    //Gives notification that there was an insert into the document.        
    @Override public void insertUpdate(DocumentEvent e)
    {
        // I want to be able to return a value or a form a detection
        // so I can tell when there has been a insert.
    }

    //Gives notification that there was a remove from the document.                     
    @Override public void   removeUpdate(DocumentEvent e)
    {
        //System.out.println("DEBUG: removeUpdate called");
    }
}

我学过一点java，但是已经有几年了，所以我有点生疏了。感谢您抽出时间。

编辑:这是我的自定义 DocumentFilter，我最初认为这会捕获粘贴，但似乎只有 DocumentListener 能够捕获粘贴。

public class CTextPaneFilter extends DocumentFilter
{
    public CTextPaneFilter(Document doc)
    {
        this(doc, 0);
    }

    public CTextPaneFilter(Document doc, int maxChars) {
        this.doc = doc;
        maxCharacters = maxChars;
    }       
    /**
    * Specifies the maximum text input length of the text pane.
    */
    public void setMaxLength(int len)
    {
        maxCharacters = len;
    }
    /**
    * Invoked prior to insertion of text into the specified Document. 
    */
    @Override public void insertString(DocumentFilter.FilterBypass fb, int offset,      String string, AttributeSet attr) throws BadLocationException
    {
    /**
    * Teuncates the inserted string so the contents
    * would be exactly maxCharacters in length.
    */
    System.out.println("insert");

    if (maxCharacters == 0 || (doc.getLength() + string.length()) <= maxCharacters) {
                        fb.insertString(offset, string, attr);
    } else {
        if (doc.getLength() < maxCharacters) {
            fb.insertString(offset, string.substring(0, maxCharacters - doc.getLength()), attr);
        }
    //Toolkit.getDefaultToolkit().beep();
    }
// other overridden methods below

Answer 1

看看DocumentFilter 。它允许您在将文本写入文档之前重新格式化文本。