如何将 InputStream 转换为 FileInputStream [英] How to convert InputStream to FileInputStream

问题描述

我的程序中有这一行:

InputStream Resource_InputStream=this.getClass().getClassLoader().getResourceAsStream("Resource_Name");

但是我怎样才能从中获取 FileInputStream [Resource_InputStream] ?

But how can I get FileInputStream from it [Resource_InputStream] ?

推荐答案

使用 ClassLoader#getResource() 如果其 URI 表示有效的本地磁盘文件系统路径.

Use ClassLoader#getResource() instead if its URI represents a valid local disk file system path.

URL resource = classLoader.getResource("resource.ext");
File file = new File(resource.toURI());
FileInputStream input = new FileInputStream(file);
// ...

如果没有(例如 JAR)，那么最好的办法是将其复制到一个临时文件中.

If it doesn't (e.g. JAR), then your best bet is to copy it into a temporary file.

Path temp = Files.createTempFile("resource-", ".ext");
Files.copy(classLoader.getResourceAsStream("resource.ext"), temp, StandardCopyOption.REPLACE_EXISTING);
FileInputStream input = new FileInputStream(temp.toFile());
// ...

也就是说，我真的没有看到这样做的任何好处，或者它必须是一个需要 FileInputStream 而不是 InputStream 的糟糕帮助类/方法所需要的.如果可以，只需修复 API 以请求 InputStream 代替.如果是第 3 方，请务必将其报告为错误.在这种特定情况下，我还会在该 API 的其余部分周围加上问号.

That said, I really don't see any benefit of doing so, or it must be required by a poor helper class/method which requires FileInputStream instead of InputStream. If you can, just fix the API to ask for an InputStream instead. If it's a 3rd party one, by all means report it as a bug. I'd in this specific case also put question marks around the remainder of that API.

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