如何在 Java 中获取父 URL？
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原文地址: http://stackoverflow.com/questions/10159186/
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How to get parent URL in Java?
提问by Eonil
In Objective-C I use -[NSURL URLByDeletingLastPathComponent]to get parent URL. What's the equivalent of this in Java?
在 Objective-C 中，我-[NSURL URLByDeletingLastPathComponent]用来获取父 URL。Java 中的 this 等价于什么？
回答by ?eurobur?
Shortest snippet of code I can think of is this:
我能想到的最短代码片段是这样的：
URI uri = new URI("http://www.stackoverflow.com/path/to/something");
URI parent = uri.getPath().endsWith("/") ? uri.resolve("..") : uri.resolve(".")
回答by ulmangt
I don't know of library function to do this in one step. However, the following (admittedly cumbersome) bit of code I believe accomplishes what you're after (and you could wrap this up in your own utility function):
我不知道可以一步完成此操作的库函数。但是，我相信以下（无可否认的繁琐）代码可以完成您所追求的（并且您可以将其包含在您自己的实用程序函数中）：
import java.io.File;
import java.net.MalformedURLException;
import java.net.URL;
public class URLTest
{
public static void main( String[] args ) throws MalformedURLException
{
// make a test url
URL url = new URL( "http://stackoverflow.com/questions/10159186/how-to-get-parent-url-in-java" );
// represent the path portion of the URL as a file
File file = new File( url.getPath( ) );
// get the parent of the file
String parentPath = file.getParent( );
// construct a new url with the parent path
URL parentUrl = new URL( url.getProtocol( ), url.getHost( ), url.getPort( ), parentPath );
System.out.println( "Child: " + url );
System.out.println( "Parent: " + parentUrl );
}
}
回答by Tomasz Szymulewski
Here is very simple solution which was the best approach in my use case:
这是非常简单的解决方案，这是我用例中的最佳方法：
private String getParent(String resourcePath) {
int index = resourcePath.lastIndexOf('/');
if (index > 0) {
return resourcePath.substring(0, index);
}
return "/";
}
I created simple function, I was inspired by the code of File::getParent. In my code there is no issue with back slashes on Windows. I assume that resourcePathis resource part of URL, without protocol, domain and port number. (e.g. /articles/sport/atricle_nr_1234)
我创建了简单的函数，我的灵感来自File::getParent. 在我的代码中，Windows 上的反斜杠没有问题。我假设这resourcePath是 URL 的资源部分，没有协议、域和端口号。（例如/articles/sport/atricle_nr_1234）
回答by Karan Arora
The simple solution offered by Guava library.
Guava 库提供的简单解决方案。
Code:
代码：
URL url = new URL("https://www.ibm.watson.co.uk");
String host = url.getHost();
InternetDomainName parent = InternetDomainName.from(host).parent(); // returns ibm.watson.co.uk
System.out.println("Immediate ancestor: "+parent);
ImmutableList<String> parts = InternetDomainName.from(host).parts();
System.out.println("Individual components: "+parts);
InternetDomainName name = InternetDomainName.from(host).topPrivateDomain(); // watson.co.uk
System.out.println("Top private domain - " + name);
Output:
输出：
Immediate ancestor: ibm.watson.co.uk
Individual components: [www, ibm, watson, co, uk]
Top private domain - watson.co.uk
For reference: https://guava.dev/releases/snapshot/api/docs/com/google/common/net/InternetDomainName.html
供参考：https: //guava.dev/releases/snapshot/api/docs/com/google/common/net/InternetDomainName.html
Dependency required:
需要依赖：
https://mvnrepository.com/artifact/com.google.guava/guava
https://mvnrepository.com/artifact/com.google.guava/guava
I'm using version 19.0
我使用的是 19.0 版
<dependency>
<groupId>com.google.guava</groupId>
<artifactId>guava</artifactId>
</dependency>
And, many more related functionalities are provided by this class InternetDomainName.
并且，此类InternetDomainName提供了更多相关功能。
