Question

我遇到了File.mkdirs（）的问题。我并行创建几百个文件夹，但似乎很少次，这个mkdir（）api返回true但是文件夹并没有真正创建（java 1.8）。我在下面贴了我的示例代码，有什么想法吗？

我的示例代码和输出位于：https://pastebin.com/aYWDw6JZ 它大部分时间都会创建文件夹，但有时会失败。

public void run() {
    // TODO Auto-generated method stub
    long randData = (long) (System.currentTimeMillis() + (Math.random() * 100000)); 
    String folderPath = File.separatorChar + "data" + File.separatorChar + "ext" + File.separatorChar + randData;
    File testFolder = new File(folderPath);
    if (!testFolder.exists()) {
        if(testFolder.mkdirs() == false)
            System.out.println(System.currentTimeMillis() + ": folder creation failed!");

    }
    String filename = testFolder + File.separator + "test.txt";
    File testFile = new File(filename);
    FileOutputStream fileOutputStream = null;
    boolean bCreated = false;
    try {
        //Thread.sleep(1000);
        if(testFolder.exists() == false) {
            System.out.println("Folder not created!");
            System.out.println("Folder: " + testFolder.getAbsolutePath() + " does not exist!");
        }else
            bCreated = true;
        fileOutputStream = new FileOutputStream(testFile);
        fileOutputStream.close();
        testFile.delete();
        testFolder.delete();

        //System.out.println("success:" + testFile.getAbsolutePath());
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
        System.out.println("Folder created? " + testFolder + ": " + bCreated);
        //back off and see if the folder is really created
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
        System.out.println("Checking again, " + testFolder.getAbsolutePath() + " created? " + testFolder.exists());
    }

}

输出：

java.io.FileNotFoundException: \data\ext\1521045935714\test.txt (The system cannot find the path specified)
    at java.io.FileOutputStream.open0(Native Method)
    at java.io.FileOutputStream.open(FileOutputStream.java:270)
    at java.io.FileOutputStream.<init>(FileOutputStream.java:213)
    at java.io.FileOutputStream.<init>(FileOutputStream.java:162)
    at DiskFolderCreationThread.run(DiskFolderCreationThread.java:30)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
Folder created? \data\ext\1521045935714: true
Checking again, C:\data\ext\1521045935714 created? false

Answer 1

只想更新我的发现作为解决方案。我发现在我的应用程序中，多个线程试图创建文件夹，并且如果两个线程同时试图创建具有相同名称的文件夹，我会看到这种mkdirs（）行为，否则就可以了。我消除了这种情况，并确保文件夹名称在线程之间是唯一的，并且现在没有问题。

Java File mkdirs（）返回true但不在load下创建文件夹

1 个答案: