如何从文件中的相对路径构造文件

Question

我正在以下位置解析基础文件： /Users/haddad/development/fspc/content/2017.dev/src/agency/individual/integration/src/forms/print.xml

然后从该文件中解析出： ../../../../include/masking.xml

因此，相对路径来自我从（基础文件）解析出来的文件的上下文

如何从该相对路径构造文件对象，以便可以读取其内容？

Answer 1

由于您标记了nio ，因此Path类使此操作变得容易。 您只需调用resolveSibling()和normalize() 。

String main = "/Users/haddad/development/fspc/content/2017.dev/src/agency/individual/integration/src/forms/print.xml";
String ref = "../../../../include/masking.xml";

System.out.println(Paths.get(main));
System.out.println(Paths.get(main).resolveSibling(ref));
System.out.println(Paths.get(main).resolveSibling(ref).normalize());

要么：

System.out.println(Paths.get(main));
System.out.println(Paths.get(main, ref));
System.out.println(Paths.get(main, ref).normalize());

产量

\Users\haddad\development\fspc\content\2017.dev\src\agency\individual\integration\src\forms\print.xml
\Users\haddad\development\fspc\content\2017.dev\src\agency\individual\integration\src\forms\..\..\..\..\include\masking.xml
\Users\haddad\development\fspc\content\2017.dev\src\agency\include\masking.xml

^{注意：我在Windows机器上运行了它，所以我当然得到了反斜杠}

---

如果您更喜欢旧的File对象，则可以使用两个参数的构造函数，然后调用getCanonicalFile() 。

System.out.println(new File(main));
System.out.println(new File(main, ref));
System.out.println(new File(main, ref).getCanonicalFile());

产量

\Users\haddad\development\fspc\content\2017.dev\src\agency\individual\integration\src\forms\print.xml
\Users\haddad\development\fspc\content\2017.dev\src\agency\individual\integration\src\forms\print.xml\..\..\..\..\include\masking.xml
C:\Users\haddad\development\fspc\content\2017.dev\src\agency\individual\include\masking.xml

Answer 2

您可以使用subpath()保留您感兴趣的路径部分，您可以将其与resolve()结合使用，以将新路径附加到：

public static void main(String[] args) {

    Path printXmlPath = Paths.get("/Users/haddad/development/fspc/content/2017.dev/src/agency/individual/integration/src/forms/print.xml");

    Path maskingXmlPath = printXmlPath.subpath(0, printXmlPath.getNameCount() - 5)
                                      .resolve("include/masking.xml");

    System.out.println(maskingXmlPath);
}

用户\\ haddad \\ development \\ fspc \\ content \\ 2017.dev \\ src \\ agency \\ include \\ masking.xml