getResourceAsStream不适用于每个类？ [英] getResourceAsStream not working for every class?

问题描述

我有一个使用一些txt文件的jar文件。为了得到它们，它使用 Class.getResourceAsStream 函数。

I have a jar file that uses some txt files. In order to get them it uses Class.getResourceAsStream function.

Class A
{
    public InputStream getInputStream(String path) throws Exception {
        try {
            return new FileInputStream(path);
        } catch (FileNotFoundException ex) {
            InputStream inputStream = getClass().getResourceAsStream(path);
            if (inputStream == null)
                throw new Exception("Failed to get input stream for file " + path);
            return inputStream;
        }
    }
}

此代码运行正常。

问题是，如果我将类A定义为 extends java.io.File ，那么我从 getResourceAsStream 为空。

Problem is, if I define class A as extends java.io.File, the InputStream I get from getResourceAsStream is null.

另外，如果我将A类作为常规类（未继承），并定义B类as：

Also, if I leave class A as regular class (not inherited), and define class B as:

Class B extends java.io.File
{
    public InputStream getInputStream(String path) throws Exception
    {
     return new A().getInputStream(path);
 }
}

返回的InputStream仍为空。

the returned InputStream is still null.

有什么问题？有没有办法从继承文件的类中访问该文件？

What is the problem? Is there a way to access the file from the class that inherits File?

谢谢，

推荐答案

我怀疑这与包相关而不是继承。

I suspect this is more to do with packages than inheritance.

如果你的班级在一个包中，然后 getResourceAsStream（）将相对于该包，除非你用/启动它（这使它成为绝对资源）。另一种方法是使用 getClass（）。getClassLoader（）。getResourceAsStream（），它不知道路径是否相对于包。

If your class is in a package, then getResourceAsStream() will be relative to that package unless you start it with "/" (which makes it an "absolute" resource). An alternative is to use getClass().getClassLoader().getResourceAsStream() which doesn't have any idea of a path being relative to a package.

只是继承文件不应该影响行为。如果您真的相信它，请发布一个简短但完整的程序来证明问题。

Just subclassing File shouldn't affect the behaviour at all. If you really believe it does, please post a short but complete program to demonstrate the problem.

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