从 Java 文本组件中获取删除的文本
JTextComponent 允许您向其 Document 添加一个 DocumentListener，它会告诉您何时添加或删除文本，以及文本的偏移量和长度。改变。 但是，它不会告诉您更改的文本是什么。
对于文本添加来说这不是什么大问题，因为您可以使用偏移量和长度来查找添加的文本。 但是，您无法使用它来查找已删除的文本，因为文本已经消失了。
以前有人遇到过这个问题吗？ 如何获取从文档中删除的字符串？
A JTextComponent allows you to add a DocumentListener to its Document, which will tell you when text was added or removed, and the offset and length of the change. It will not, however, tell you what the text of the change was.
This is not much of a problem for text addition, as you can use the offset and the length to find the added text. However, you can't use it to find the deleted text, as the text is already gone.
Has anyone run into this problem before? How can you get the string that was deleted from a document?
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将
DocumentFilter安装到AbstractDocument中。（顺便说一句：在 Swing 中，通常最好直接进入模型（在本例中为文档）。）
Install a
DocumentFilterinto theAbstractDocument.(BTW: In Swing it's usually best to go straight to the model (in this case document).)
每次添加文本时，将文档存储在内存中。 每次删除文本时，请将文档与上次存储的内容进行比较，以确定删除的内容。
Every time text is added, store the document in memory. Every time text is removed, compare the document to what was last stored to determine what was removed.
将文本的原始版本存储在属性中，您仍然可以在其中执行“offset-length-trick”来获取删除的字符串。 应该做得很好
store the original version of the text in a property where you can still do the "offset-length-trick" to get the removed string. should do fine