Java 如何获取 inputStream 正在使用的文件名？
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How to get the file name of the one being used by a inputStream?
提问by user657592
I have a method accepts an InputStream as an argument. How do I find which file is being handled by the passed handler?
我有一个方法接受 InputStream 作为参数。如何找到传递的处理程序正在处理哪个文件？
For example:
例如：
public performSomething(InputStream inputStream) {
System.out.println(FILENAME);
}
What should the FILENAME be replaced with such that the name of the file opened by the handler is displayed.
应该用什么来替换 FILENAME，以便显示处理程序打开的文件的名称。
采纳答案by Svetlin Zarev
I guess you cannot, because the input stream might not belong to a file. It can be SocketInputStream, or ByteArrayInputStreamfor example. The input stream is just an abstraction
我猜你不能，因为输入流可能不属于一个文件。它可以是SocketInputStream，或者ByteArrayInputStream例如。输入流只是一个抽象
回答by Java Curious ?
An input stream can be created to read from a file or from any other source of data. Therefore it makes no sense to have a filename attached to an input stream.
可以创建输入流以从文件或任何其他数据源读取。因此，将文件名附加到输入流是没有意义的。
Simple Example :
简单示例：
InputStream input= assetInfo.openStream();
File t = new File("");
OutputStream out = new FileOutputStream(t);
int read=0;
byte[] bytes = new byte[1024];
while((read = input.read(bytes))!= -1){
out.write(bytes, 0, read);
}
Look in assetInfo to see if that class exposes that data (you can even look inside the class using reflection). Note that the creator or assetInfo made a design mistake not exposing this information, OR you are trying to make one now.
查看 assetInfo 以查看该类是否公开了该数据（您甚至可以使用反射查看该类的内部）。请注意，创建者或资产信息犯了一个设计错误，没有公开此信息，或者您现在正在尝试制作一个。
回答by Marko Topolnik
Even if you are certain you have a FileInputStream, you will still be unable to get the underlying file. FileInputStreamdoes not retain its Fileargument, but immediately opens the file and retains just the FileDescriptor, a wrapper around the native inthandle to the OS resource.
即使你确定你有一个FileInputStream，你仍然无法获得底层文件。FileInputStream不保留其File参数，但会立即打开文件并仅保留FileDescriptor, 围绕int操作系统资源的本机句柄的包装器。
As of OpenJDK version 7, Update 40, a String pathvariable has been introduced, so with some luck you may try to reflectivelyget it.
从 OpenJDK 版本 7 Update 40 开始，String path已经引入了一个变量，所以如果运气好的话，您可以尝试反射性地获取它。
Of course, this can be nothing more than heurstics. There is no official way through the public API.
当然，这无非是启发式。没有通过公共 API 的官方方法。
