给出两条绝对路径,例如
/var/data/stuff/xyz.dat
/var/data
如何创建一个以第二条路径为基础的相对路径?在上面的例子中,结果应该是:./stuff/xyz.dat
给出两条绝对路径,例如
/var/data/stuff/xyz.dat
/var/data
如何创建一个以第二条路径为基础的相对路径?在上面的例子中,结果应该是:./stuff/xyz.dat
当前回答
如果你知道第二个字符串是第一个字符串的一部分:
String s1 = "/var/data/stuff/xyz.dat";
String s2 = "/var/data";
String s3 = s1.substring(s2.length());
或者,如果你真的想把句号放在开头,就像你的例子中那样:
String s3 = ".".concat(s1.substring(s2.length()));
其他回答
从Java 7开始,你可以使用relativize方法:
import java.nio.file.Path;
import java.nio.file.Paths;
public class Test {
public static void main(String[] args) {
Path pathAbsolute = Paths.get("/var/data/stuff/xyz.dat");
Path pathBase = Paths.get("/var/data");
Path pathRelative = pathBase.relativize(pathAbsolute);
System.out.println(pathRelative);
}
}
输出:
stuff/xyz.dat
我假设你有fromPath(一个文件夹的绝对路径),和toPath(一个文件夹/文件的绝对路径),你正在寻找一个路径,代表文件/文件夹在toPath作为一个相对路径从fromPath(你当前的工作目录是fromPath),然后像这样的工作:
public static String getRelativePath(String fromPath, String toPath) {
// This weirdness is because a separator of '/' messes with String.split()
String regexCharacter = File.separator;
if (File.separatorChar == '\\') {
regexCharacter = "\\\\";
}
String[] fromSplit = fromPath.split(regexCharacter);
String[] toSplit = toPath.split(regexCharacter);
// Find the common path
int common = 0;
while (fromSplit[common].equals(toSplit[common])) {
common++;
}
StringBuffer result = new StringBuffer(".");
// Work your way up the FROM path to common ground
for (int i = common; i < fromSplit.length; i++) {
result.append(File.separatorChar).append("..");
}
// Work your way down the TO path
for (int i = common; i < toSplit.length; i++) {
result.append(File.separatorChar).append(toSplit[i]);
}
return result.toString();
}
如果路径在JRE 1.5运行时或maven插件中不可用
package org.afc.util;
import java.io.File;
import java.util.LinkedList;
import java.util.List;
public class FileUtil {
public static String getRelativePath(String basePath, String filePath) {
return getRelativePath(new File(basePath), new File(filePath));
}
public static String getRelativePath(File base, File file) {
List<String> bases = new LinkedList<String>();
bases.add(0, base.getName());
for (File parent = base.getParentFile(); parent != null; parent = parent.getParentFile()) {
bases.add(0, parent.getName());
}
List<String> files = new LinkedList<String>();
files.add(0, file.getName());
for (File parent = file.getParentFile(); parent != null; parent = parent.getParentFile()) {
files.add(0, parent.getName());
}
int overlapIndex = 0;
while (overlapIndex < bases.size() && overlapIndex < files.size() && bases.get(overlapIndex).equals(files.get(overlapIndex))) {
overlapIndex++;
}
StringBuilder relativePath = new StringBuilder();
for (int i = overlapIndex; i < bases.size(); i++) {
relativePath.append("..").append(File.separatorChar);
}
for (int i = overlapIndex; i < files.size(); i++) {
relativePath.append(files.get(i)).append(File.separatorChar);
}
relativePath.deleteCharAt(relativePath.length() - 1);
return relativePath.toString();
}
}
这有点迂回,但为什么不使用URI呢?它有一个相对化方法可以帮你做所有必要的检查。
String path = "/var/data/stuff/xyz.dat";
String base = "/var/data";
String relative = new File(base).toURI().relativize(new File(path).toURI()).getPath();
// relative == "stuff/xyz.dat"
请注意文件路径是java.nio.file。正如@Jirka Meluzin在另一个答案中指出的那样,自Java 1.7以来,路径#相对化。
在Java 7及以后的版本中,你可以简单地使用(与URI相比,它没有错误):
Path#relativize(Path)