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
当使用java.net.URI.relativize时,你应该注意Java错误: JDK-6226081 (URI应该能够将路径与部分根相对化)
目前,URI的relativize()方法只在一个URI是另一个URI的前缀时才会相对化URI。
这本质上意味着java.net.URI.relativize将不会创建“…这是给你的。
其他回答
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()));
Psuedo-code:
使用路径分隔符("/")拆分字符串 通过迭代拆分字符串的结果来找到最大的公共路径(因此在两个示例中,您最终会得到"/var/data"或"/a") 返回“。”+ whicheverPathIsLonger.substring (commonPath.length);
这里有一个其他库免费的解决方案:
Path sourceFile = Paths.get("some/common/path/example/a/b/c/f1.txt");
Path targetFile = Paths.get("some/common/path/example/d/e/f2.txt");
Path relativePath = sourceFile.relativize(targetFile);
System.out.println(relativePath);
输出
..\..\..\..\d\e\f2.txt
[编辑]实际上它输出更多。因为源文件不是目录。对于我的情况,正确的解决方案是:
Path sourceFile = Paths.get(new File("some/common/path/example/a/b/c/f1.txt").parent());
Path targetFile = Paths.get("some/common/path/example/d/e/f2.txt");
Path relativePath = sourceFile.relativize(targetFile);
System.out.println(relativePath);
酷! !我需要一些类似这样的代码,但用于比较Linux机器上的目录路径。我发现这在父目录为目标的情况下不起作用。
下面是该方法的目录友好版本:
public static String getRelativePath(String targetPath, String basePath,
String pathSeparator) {
boolean isDir = false;
{
File f = new File(targetPath);
isDir = f.isDirectory();
}
// We need the -1 argument to split to make sure we get a trailing
// "" token if the base ends in the path separator and is therefore
// a directory. We require directory paths to end in the path
// separator -- otherwise they are indistinguishable from files.
String[] base = basePath.split(Pattern.quote(pathSeparator), -1);
String[] target = targetPath.split(Pattern.quote(pathSeparator), 0);
// First get all the common elements. Store them as a string,
// and also count how many of them there are.
String common = "";
int commonIndex = 0;
for (int i = 0; i < target.length && i < base.length; i++) {
if (target[i].equals(base[i])) {
common += target[i] + pathSeparator;
commonIndex++;
}
else break;
}
if (commonIndex == 0)
{
// Whoops -- not even a single common path element. This most
// likely indicates differing drive letters, like C: and D:.
// These paths cannot be relativized. Return the target path.
return targetPath;
// This should never happen when all absolute paths
// begin with / as in *nix.
}
String relative = "";
if (base.length == commonIndex) {
// Comment this out if you prefer that a relative path not start with ./
relative = "." + pathSeparator;
}
else {
int numDirsUp = base.length - commonIndex - (isDir?0:1); /* only subtract 1 if it is a file. */
// The number of directories we have to backtrack is the length of
// the base path MINUS the number of common path elements, minus
// one because the last element in the path isn't a directory.
for (int i = 1; i <= (numDirsUp); i++) {
relative += ".." + pathSeparator;
}
}
//if we are comparing directories then we
if (targetPath.length() > common.length()) {
//it's OK, it isn't a directory
relative += targetPath.substring(common.length());
}
return relative;
}
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。