如何在 Ubuntu 中检查 Java 中的 isFile() 或 isDirectory() 函数?

本文介绍了如何在 Ubuntu 中检查 Java 中的 isFile() 或 isDirectory() 函数?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

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在 ubuntu 中，isFile() 和 isDirectory() 不能完美运行.我使用此代码来确定某些内容是文件还是目录:

In ubuntu, isFile() and isDirectory() don't work perfectly. I used this code to find out if something is a file or directory:

boolean fileName= file.getName().lastIndexOf('.') == -1;

但问题是我创建了一个名为 bhargav.panchal 的文件夹.有了上面的功能，这个文件夹就被认为是一个文件，而不是一个文件夹.

But the problem is that I made a folder named bhargav.panchal. With the above function, this folder is considered as a file, not a folder.

File file=new File("/home/asd/My_Shared_File/bhargav.panchal");

if(file.exists()){
    if(!file.isDirectory()) {
        Toast.makeText(activity, "This is File", Toast.LENGTH_SHORT).show();
    } else {
        Toast.makeText(activity, "This is Directory", Toast.LENGTH_SHORT).show();
    }
} else {
    Toast.makeText(activity, "File or Directory doesn't exist.", Toast.LENGTH_SHORT).show();
}

在这种情况下，isDirectory() 和 isFile() 方法总是返回 false.

In this condition, the isDirectory() and isFile() methods always return false.

推荐答案

不，你有什么地方错了.相反，您无法使用 DVM 访问外部环境.

No, you are wrong somewhere. On the contrary you cant access external environment with DVM.

原因:基于操作系统级别的应用程序之间不可能相互干扰安全性和 Dalvik 虚拟机仅限于单个操作系统进程，Dalvik 本身并不关心运行时安全.尽管 Dalvik 不依赖于安全性，但有趣的是，大多数的标准 Java 安全类保留在 Android 发行版中.这些包括java.lang.SecurityManager 和 java.security 包中的一些类.在标准 Java 中环境中，SecurityManger 的作用类似于操作系统进程级安全性.安卓.SecurityManager 通常控制对 JVM 外部资源的访问，例如文件、进程和网络.在 Android 发行版中，标准的安全框架是显然存在于应用程序在其自己的应用程序空间 中使用但既不完全为进程间安全实现或配置(不存在 java.policy 文件).

reason : it is not possible for applications to interfere with each other based on the OS level security and Dalvik VMs are confined to a single OS process, Dalvik itself is not concerned with runtime security. Although Dalvik is not relied upon for security, it is interesting to note that most of the standard Java security classes remain in the Android distribution. These include the java.lang.SecurityManager and some of the classes in the java.security package. In standard Java environments, the SecurityManger plays the role analogous to the OS process-level security in Android. The SecurityManager typically controls access to resources external to the JVM such as files, processes, and the network. In the Android distribution, the standard security framework is apparently present for applications to use within their own application space but is neither fully implemented nor configured (no java.policy files are present) for interprocess security.

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