Java-Desktop.getDesktop().open()-等待文件打开? [英] Java - Desktop.getDesktop().open() - Wait until file is open?

问题描述

我正在寻找一种解决方案，以等待文件打开.我的应用程序打开pdf文件并显示用户输入对话框，但该对话框与pdf文件重叠.pdf文件完全打开时，是否可以添加侦听器或其他方法来显示我的对话框?

I'm searching for a solution to wait until a file is opened. My application opens pdf files and displays user-input dialogs but the dialog is overlapped by the pdf file. Is there a way to add a listener or something to show my dialog when the pdf file is fully open?

我可以使用延迟或暂停，但这并不是我想要的.

I could use a delay or pause but that's not exactly what I want.

我正在使用

Desktop.getDesktop().open(new File("my.pdf"));

推荐答案

要打开我刚刚创建的文件，请使用以下方法:

To open a file I just created, I use this method:

// Returns true if the file is unlocked or if it becomes unlocked in the next x seconds
public static boolean isFileUnlockedWithTimeout(File file, int timeoutInSeconds) {
    if (!file.exists())
        // The file does not exist. So it's not locked. (Another approach could be to throw an exception...)
        return true; 
    long endTime = System.currentTimeMillis() + 1000 * timeoutInSeconds;
    while (true) {
        if (file.renameTo(file)) {
            // The file is not locked
            return true;
        }
        if (System.currentTimeMillis() > endTime) {
            // After the timeout
            return false;
        }
        // Wait 1/4 sec.
        try { TimeUnit.MILLISECONDS.sleep(250); } catch (InterruptedException e) {}
    }
}

适用于第一个问题:

File myFile = new File("my.pdf");
if (isFileUnlockedWithTimeout(myfile, 5)) {
    // File is not locked, we can open it
    Desktop.getDesktop().open(myFile);
} else {
    System.out.println("File is locked. Cannot open.");
}

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