java.net.URI.relativize不适用于JAR URI [英] java.net.URI.relativize doesn't work with JAR URIs
问题描述
我有两个URI对象。一个指向JAR文件中的文件夹，另一个指向同一JAR文件中的文件。该文件位于第一个URI指定的目录的子文件夹中。我喜欢创建一个相对URI，因此生成的URI只包含JAR中文件的相对路径。
I have two URI objects. One is pointing to a folder in a JAR file, and another is pointing to a file in the same JAR file. The file is in a subfolder of the directory specified by the first URI. I like to create a relative URI so the resulting URI only containing the relative path to the file in the JAR.
-
文件夹URI
Folder URI
jar:file:/C:/Users/inagy/.m2/repository/hu/inagy/my-config-artifact/2.0-SNAPSHOT/my-config-artifact-2.0-SNAPSHOT.jar!/conf/
资源URI
Resource URI
jar:file:/C:/Users/inagy/.m2/repository/hu/inagy/my-config-artifact/2.0-SNAPSHOT/my-config-artifact-2.0-SNAPSHOT.jar!/conf/somesubpath/someconfig.xml
在调用 folderUri.relativize（resourceURI）后，我希望得到以下URI：
After calling folderUri.relativize(resourceURI) i'm expecting the following URI as a result:
somesubpath/someconfig.xml
然而，根据 URI类的Javadoc 即JDK代码发现这两条路径彼此不相对。
However i get resourceURI back which mean according to the URI class's Javadoc that the JDK code find this two paths non relative to each other.
这是一个错误还是我做错了什么？
Is this a bug or i'm doing something wrong?
推荐答案
我也对此感到有点恼火。答案是没有对JAR文件的语义做了什么 - 它与 jar： URI的语法有关。要进行相对化，URI必须分层且不透明。您将从JavaDoc for java.net.URI中注意到：
I've been mildly annoyed by this too. The answer has nothing do to with the semantics of JAR files—it has to do with the syntax of jar: URIs. To be "relativized," a URI has to be hierarchical and not opaque. You will note from the JavaDoc for java.net.URI that:
最高级别的URI引用（以下简称URI）字符串形式的语法
At the highest level a URI reference (hereinafter simply "URI") in string form has the syntax
[scheme:]scheme-specific-part[#fragment]
...
不透明的URI是绝对URI，其方案 - 特定部分不以斜杠字符（'/'）开头。不透明的URI不需要进一步解析。
An opaque URI is an absolute URI whose scheme-specific part does not begin with a slash character ('/'). Opaque URIs are not subject to further parsing.
...
分层URI需要根据语法进一步解析
A hierarchical URI is subject to further parsing according to the syntax
[scheme:][//authority][path][?query][#fragment]
JAR URI，如 jar：file：///home/me/foo.jar ！/ conf / 被解析为：
A JAR URI like jar:file:///home/me/foo.jar!/conf/ is parsed as:
- scheme =
jar - scheme-specific-part =
file：///home/me/foo.jar！/ conf / - fragment =（none）
因为特定于方案的部分不是以 / ，它不能被视为分层URI。 URI类不会特别处理 jar：（或任何）URI，因此它无法识别 file：// part是 层次结构的嵌套URI。
Because the scheme-specific-part does not begin with "/," it cannot be considered a hierarchical URI. The URI class does not treat jar: (or any) URIs specially, so it cannot recognize that the file:// part is a nested URI that is hierarchical.
因为 jar： URI是不透明且不分层，它们受 URI＃relativize（）：
Since jar: URIs are opaque and not hierarchical, they are subject to the behavior documented for URI#relativize():
给定URI对此的相对化URI计算为
如下：
The relativization of the given URI against this URI is computed as follows:
- 如果此URI或给定的URI不透明，[...]，则返回给定的URI。
编辑：遗漏了一个关键部分关于不透明的URI。
EDIT: Left out a crucial part about opaque URIs.
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