java 在指定目录启动 JFileChooser 并仅显示特定类型的文件
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原文地址: http://stackoverflow.com/questions/15954770/
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Starting a JFileChooser at a specified directory and only showing files of a specific type
提问by corvid
I have a program utilizing a JFileChooser. To be brief, the full program is a GUI which allows users to manipulate PNGs and JPGs. I would like to make it so that the JFileChooser instantly opens to the picture directory (windows). When the user opens their JFileChooser, it would open directly to the pictures library C:\Users\(USER)\Pictures
我有一个使用 JFileChooser 的程序。简而言之，完整的程序是一个 GUI，允许用户操作 PNG 和 JPG。我想让 JFileChooser 立即打开到图片目录（窗口）。当用户打开他们的 JFileChooser 时，它会直接打开图片库 C:\Users\(USER)\Pictures
Furthermore, it would be nice to ONLY show files of a specific type (PNGs and JPGs). Many programs seem to be able to do this; only allowing selection of specific files. Does JFileChooser allow such a thing? Currently, I am using a massively unreliable, run around method to reject non-PNGs/JPGs.
此外，最好只显示特定类型（PNG 和 JPG）的文件。许多程序似乎能够做到这一点；只允许选择特定文件。JFileChooser 是否允许这样的事情？目前，我正在使用一种非常不可靠的运行方法来拒绝非 PNG/JPG。
The following refers to the "browse" button of the GUI, in which a user will select their picture for editing and it will display it on the screen.
下面指的是GUI的“浏览”按钮，用户可以在其中选择要编辑的图片并将其显示在屏幕上。
try {
int val = filec.showOpenDialog(GridCreator.this);
if(val==JFileChooser.APPROVE_OPTION) {
File unfiltered_picture = filec.getSelectedFile();
//get the extension of the file
extension=unfiltered_picture.getPath();
int index=extension.indexOf(".");
extension=extension.substring(index+1, extension.length());
//if the file is not jpg, png, or jpeg, reject it and send a message to the user.
if(!extension.matches("[jJ][pP][gG]") && !extension.matches("[pP][nN][gG]") && !extension.matches("[jJ][pP][eE][gG]")) {
JOptionPane.showMessageDialog(null,
"cannot load file. File must be of type png, jpeg, or jpg. \n Your file is of type " + extension,
"Error: improper file",
JOptionPane.OK_OPTION);
//if the file is of the proper type, display it to the user on the img JLabel.
} else {
finalImage = ImageIO.read(unfiltered_picture);
ImageIcon imgIcon = new ImageIcon();
imgIcon.setImage(finalImage);
img.setIcon(imgIcon);
img.invalidate();
h_divide.setValue(0);
v_divide.setValue(0);
}
}
} catch(IOException exception) {
exception.printStackTrace();
}
Thank you.
谢谢你。
回答by Boris the Spider
You need to construct your JFileChooserwith the directory you want to start in and then pass a FileFilterinto it before setting visible.
您需要JFileChooser使用要开始的目录构建您的目录，然后FileFilter在设置可见之前将a 传递给它。
final JFileChooser fileChooser = new JFileChooser(new File("File to start in"));
fileChooser.setFileFilter(new FileFilter() {
@Override
public boolean accept(File f) {
if (f.isDirectory()) {
return true;
}
final String name = f.getName();
return name.endsWith(".png") || name.endsWith(".jpg");
}
@Override
public String getDescription() {
return "*.png,*.jpg";
}
});
fileChooser.showOpenDialog(GridCreator.this);
This example filters for files ending in ".png" or ".jpg".
此示例过滤以“.png”或“.jpg”结尾的文件。
回答by E. Keller
Putting it all into a concise form, here is a flexible file chooser routine. It specifies initial directory and file type and it furnishes the result both as a file or a complete path name. You may also want to set your entire program into native interface mode by placing the setLookAndFeel command at the Main entry point to your program.
将所有内容简化为简洁的形式，这是一个灵活的文件选择器例程。它指定初始目录和文件类型，并将结果作为文件或完整路径名提供。您可能还想通过将 setLookAndFeel 命令放置在程序的 Main 入口点，将整个程序设置为本地界面模式。
String[] fileChooser(Component parent, String dir, String typeFile) {
File dirFile = new File(dir);
JFileChooser chooser = new JFileChooser();
// e.g. typeFile = "txt", "jpg", etc.
FileNameExtensionFilter filter =
new FileNameExtensionFilter("Choose a "+typeFile+" file",
typeFile);
chooser.setFileFilter(filter);
chooser.setCurrentDirectory(dirFile);
int returnVal = chooser.showOpenDialog(parent);
String[] selectedDirFile = new String[2];
if(returnVal == JFileChooser.APPROVE_OPTION) {
// full path
selectedDirFile[0] = chooser.getSelectedFile().getPath();
// just filename
selectedDirFile[1] = chooser.getSelectedFile().getName();
}
return selectedDirFile;
}
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
}
catch (Exception e) {
e.printStackTrace();
}
