this.getClass（）。getResource（“”）。getPath（）返回错误的路径 [英] this.getClass().getResource("").getPath() returns an incorrect path

问题描述

我目前正在为我的计算机科学决赛编写一个小的简单Java程序，该程序需要获取当前正在运行的类的路径。类文件位于C：\2013\game\文件夹中。

I am currently making a small simple Java program for my Computer Science Final, which needs to get the path of the current running class. The class files are in the C:\2013\game\ folder.

要获取此路径，请在主类构造函数中将此代码段称为： / p>

To get this path, I call this code segment in my main class constructor:

public game(){
    String testPath = this.getClass().getResource("").getPath();
    //Rest of game
}

但是，此命令返回此命令字符串： /尽管正确的输出是 C：/ 2013 / game
另外，我尝试通过使用以下代码来纠正此问题：

However, this command instead returns this String: "/" despite the correct output being "C:/2013/game" Additionally, I attempted to rectify this by using this code:

public game(){
    String testPath = this.getClass().getClassLoader().getResource("").getPath();
}

这将返回NullPointerException，该异常源于getClassLoader（）返回null的事实，尽管我在Eclipse IDE上工作。有想法吗？

This returns a NullPointerException, which originates from the fact that getClassLoader() returns null, despite working on my Eclipse IDE. Any Ideas?

推荐答案

如果您要在与代码相同的路径中加载文件，则建议您将其放入

If you want to load a file in the same path as the code then I suggest you put it in the same root folder as the code and not the same path as the class.

原因：类可以放在jar中，数据文件可以放在同一jar中，但它的更多信息

Reason : class can be inside a jar, data file can be put in same jar but its more difficult to edit and update then.

还建议您查看注释中建议的首选项类： http://www.javacodegeeks.com/2011/09/use-javautilprefspreferences-instead-of.html ，尽管在​​某些情况下，我认为可以拥有自己的数据/ excel / csv / java.util.Properties文件

Also suggest you see the preferences class suggested in comments : http://www.javacodegeeks.com/2011/09/use-javautilprefspreferences-instead-of.html though in some cases I think its okay to have your own data/ excel/csv/ java.util.Properties file

不知道为什么它可以在日食中工作，但我建议您集中精力从命令提示符/终端运行它，因为它是上线时的真实模式

Not sure about why it is working in eclipse but I would suggest you focus on running it from a command prompt/ terminal as that is the 'real mode' when it goes live

您可以只要求您的课程

    String s = getClass().getName();
    int i = s.lastIndexOf(".");
    if(i > -1) s = s.substring(i + 1);
    s = s + ".class";
    System.out.println("name " +s);
    Object testPath = this.getClass().getResource(s);
    System.out.println(testPath);

这将为您提供

名称TstPath.class
文件：/java/Projects/tests3b/build/classes/s/TstPath.class

name TstPath.class file:/java/Projects/tests3b/build/classes/s/TstPath.class

这是我的月食构建路径...

Which is my eclipse build path ...

需要对此进行解析，以获取加载类的路径。

need to parse this to get the path where the class was loaded.

记住：

1. 应用程序可以从其他地方启动


2. 类可以放在jar中，则路径将不同（将指向其中的一个jar和文件


3. 类路径在运行时可以有很多，并指向1


4. a类可能是在运行时通过网络/代理/注入等创建的，因此没有文件源，因此这不是通用的解决方案。


5. 思考一下您想在更高层次上实现的目标并发布该问题，这意味着您为什么要使用此路径？



6. 您是否想要应用程序路径：-

1. App could be started from elsewhere
2. class can be in jar then path will be different (will point to a jar and file inside that
3. classpaths can be many at runtime and point 1
4. a class might be made at runtime via network/ Proxy / injection etc and thus not have a file source, so this is not a generic solution.
5. think what you want to acheive at a higher level and post that question. meaning why do you want this path?

6. do you want the app path :-

File f = new File（ ./）;

f.getCanonicalPath（）; // ...

File f = new File("./");
f.getCanonicalPath();//...

因此可以从文件夹c：\app1\run\启动应用程序

So an app can be started from folder c:\app1\run\

罐子可能是在c：\app1\libsMain\myapp.jar

The jar could be at c:\app1\libsMain\myapp.jar

和一个辅助jar可以在c：\commonlibs\set1

and a helper jar could be at c:\commonlibs\set1

因此，这只会告诉您JVM在哪里找到您的类，这可能是您需要的，也可能不是。

So this will only tell you where the JVM found your class, that may or maynot be what you need.

如果在jar中将在Unix或Windows中为您提供类似的信息

if inside a jar will give you some thing like this in unix or windows

jar：file：c：\app\my.jar！/ s /TstPath.class

jar:file:c:\app\my.jar!/s/TstPath.class

如果package是s并且class是TstPath，则可以确保它可以正常工作，因为类必须存在...

If package is s and class is TstPath, you can be sure this will work as the class has to be there ...

现在要解析它，您可以查找您的类名并删除/或\，直到获得所需的路径为止。字符串lastIndexOf将帮助

now to parse this you can look for your class name and remove / or \ till you get path you want. String lastIndexOf will help

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