应该关闭Class.getResourceAsStream吗？ [英] should Class.getResourceAsStream be closed?

问题描述

我想知道这是否是必需的，因为当我使用这个方法时，正在从类路径中读取文件。 不关闭会导致内存泄漏。

I was wondering if this is required since when i use this method, the file is being read from the classpath. Does "not closing" it lead to a memory leak.

我如何测试此类内存泄漏？

How can i test for such memory leaks?

推荐答案

您假设 Class.getResourceAsStream（）将始终返回指向类JAR文件中的文件的流。这是不正确的。您的类路径也可能包含文件夹，在这种情况下， Class.getResourceAsStream（）将返回 FileInputStream 。其他一些类加载器也可能返回其他类型的资源，例如远程文件（在URLClassLoader的情况下）。

You are assuming that Class.getResourceAsStream() will always return a stream that points to a file inside your class' JAR file. This is incorrect. Your classpath may also contains folders, in which case Class.getResourceAsStream() will return a FileInputStream. Some other class loaders might also return other type of resources, such as remote files (in the case of a URLClassLoader).

即使在JAR文件的情况下，它也是如此有可能该实现通过任何方式维护JAR文件中的持久视图到您正在访问的文件的压缩字节。也许它持有内存映射 ByteBuffer ...

Even in the case of a JAR file, it is possible that the implementation maintain, by whatever mean, a persistant view inside the JAR file to the compressed bytes of the file you are accessing. Maybe it is holding upon a memory mapped ByteBuffer...

为什么要抓住机会？你应该总是关闭流（以及其他任何Closeable，实际上），无论它们是如何给你的。

Why take the chance? You should always close streams (and any other Closeable, actually), no matter how they were given to you.

至于检测泄漏，最好的策略是获得一个VM关闭时的内存转储，然后用一些工具进行分析。两个流行的工具是 jhat 和 Eclipse垫。

As for detecting leaks, the best strategy is to obtain a memory dump at the time the VM is shut down, then analyze it with some tool. Two popular tools are jhat and Eclipse mat.

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