使用JFileChooser设置默认保存扩展名 [英] Set default saving extension with JFileChooser

问题描述

我正在尝试使用 JFileChooser 保存文件。但是，我似乎遇到了一些问题。这是我的代码：

I'm trying to save a file using JFileChooser. However, I seem to be having some trouble with it. Here's my code:

    if (e.getSource() == saveMenu) {

        JFileChooser chooser = new JFileChooser();
        chooser.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);

        FileNameExtensionFilter xmlFilter = new FileNameExtensionFilter("xml files (*.xml)", "xml");
        // add filters
        chooser.addChoosableFileFilter(xmlFilter);
        chooser.setFileFilter(xmlFilter);

        int result = chooser.showSaveDialog(Simulation.this);

        if (result == chooser.APPROVE_OPTION) {
            writeToXML(chooser.getSelectedFile());
        }

    }

这不强制文件有一个 .xml 扩展名，所以我尝试使用以下代码强制保存文件，扩展名为.xml

This doesn't force the file to have a .xml extension, so I've tried to use the following code to force the file to be saved with the extension .xml

     OutputFormat format = OutputFormat.createPrettyPrint();
     format.setEncoding("UTF-8");
     XMLWriter xmlWriter = null;
     try {              
         xmlWriter = new XMLWriter(new OutputStreamWriter(
                 new FileOutputStream(f+".xml"), "UTF8"),
                 format);

然而，有了这个，我无法阻止用户编写 xpto。 xml 在 JFileChooser 中，如果他们这样做，该文件将有两个扩展名：它将是一个名为 xpto.xml.xml

However, with this I can't prevent the user from writing xpto.xml in the JFileChooser and if they do that, the file will have "two extensions": it will be a file named xpto.xml.xml

所以我的问题是：

• 我怎样才能使 JFileChooser 默认保存xml文件？


• 如果用户插入文件名如xpto.xml，如何将其保存为xpto.xml而不是xpto.xml.xml？

• How can I make the JFileChooser save an xml file by default?
• If the user inserts a file name like xpto.xml, how can I save it as xpto.xml and not xpto.xml.xml?

推荐答案

正如您所注意到的， JFileChooser 在保存时不强制执行 FileFilter 。它会使显示的对话框中的现有非XML文件变灰，但就是这样。要强制执行文件名，您必须完成所有工作。 （这不仅仅是JFileChooser吮吸的问题 - 处理这是一个复杂的问题。你的希望你的用户能够命名他们的文件 xml.xml。 xml.xml 。）

As you've noticed, JFileChooser doesn't enforce the FileFilter on a save. It will grey-out the existing non-XML file in the dialog it displays, but that's it. To enforce the filename, you have to do all the work. (This isn't just a matter of JFileChooser sucking -- it's a complex problem to deal with. Your might want your users to be able to name their files xml.xml.xml.xml.)

在您的情况下，我建议使用 FilenameUtils ：

In your case, I recommend using FilenameUtils from Commons IO:

File file = chooser.getSelectedFile();
if (FilenameUtils.getExtension(file.getName()).equalsIgnoreCase("xml")) {
    // filename is OK as-is
} else {
    file = new File(file.toString() + ".xml");  // append .xml if "foo.jpg.xml" is OK
    file = new File(file.getParentFile(), FilenameUtils.getBaseName(file.getName())+".xml"); // ALTERNATIVELY: remove the extension (if any) and replace it with ".xml"
}

如果您想在此处的保存对话框中使用多种类型，还有一些想法可以做：如何使用JFileChooser保存文件？

There's also some ideas for what to do if you want multiple types in the save dialog here: How to save file using JFileChooser?

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